Xia Yin

# APK Extractor — Technical Annex

**Companion to:** APK_FEATURES_PDD.md
**Audience:** Engineers implementing the APK extractors
**Date:** 2026-02-21

---

## Table of Contents

1. [File Structure](#1-file-structure)
2. [Dependencies Setup](#2-dependencies-setup)
3. [Base Class: APKExtractor](#3-base-class-apkextractor)
4. [Dataclass Definitions](#4-dataclass-definitions)
5. [Tag Enum Updates](#5-tag-enum-updates)
6. [Extractor Implementation Details](#6-extractor-implementation-details)
7. [Ingestor Integration](#7-ingestor-integration)
8. [Hashes Dataclass Update](#8-hashes-dataclass-update)
9. [ClickHouse Schema](#9-clickhouse-schema)
10. [Androguard API Reference](#10-androguard-api-reference)
11. [Known Packer/Protector Signatures](#11-known-packerprotector-signatures)
12. [Sensitive API Categorization Reference](#12-sensitive-api-categorization-reference)

---

## 1. File Structure

Create the following files:

```
redb/extractors/
├── apk_extractor.py                          # APKExtractor base class
├── apk_extractors/
│   ├── __init__.py
│   ├── apk_features.py                       # APKFeaturesExtractor
│   ├── apk_manifest.py                       # APKManifestExtractor
│   ├── apk_permissions.py                    # APKPermissionsExtractor
│   ├── apk_signature.py                      # APKSignatureExtractor
│   ├── apk_dex.py                            # APKDexExtractor
│   ├── apk_resources.py                      # APKResourceExtractor
│   ├── apk_native_libs.py                    # APKNativeLibExtractor
│   └── apk_inconsistency_tests.py            # APKInconsistencyTestsExtractor
```

Modified files:

```
redb/extractors/enum.py                       # Add APK tags
redb/models/dataclasses.py                    # Add APK dataclasses + permhash field in Hashes
redb/ingestor.py                              # Wire up APK dispatch
requirements.txt                              # Add androguard, permhash
```

---

## 2. Dependencies Setup

Add to `requirements.txt`:

```
androguard>=4.1
permhash
```

Install and verify:

```bash
pip install androguard permhash
python -c "from androguard.core.apk import APK; print('androguard OK')"
python -c "import permhash; print('permhash OK')"
```

---

## 3. Base Class: APKExtractor

**File:** `redb/extractors/apk_extractor.py`

Follow the exact pattern of `PEExtractor` (`redb/extractors/pe_extractor.py`) and `MachOExtractor` (`redb/extractors/macho_extractor.py`).

```python
import logging
from abc import ABCMeta, abstractmethod
import zipfile

from androguard.core.apk import APK

from redb.extractors.extractor import Extractor

logger = logging.getLogger(__name__)


@abstractmethod
class APKExtractor(Extractor, metaclass=ABCMeta):

    def __init__(
        self,
        filepath,
        log,
        exporters=None,
        index_prefix=None,
        elastic_index=None,
        known_benign=False,
        known_malicious=False,
        apk=None,
    ):
        super().__init__(
            filepath,
            log,
            exporters,
            index_prefix,
            elastic_index,
            known_benign,
            known_malicious
        )
        self.apk = apk if apk else self._generate_apk_object()

    def _generate_apk_object(self):
        """Parse APK using androguard."""
        apk = None
        try:
            apk = APK(self.filepath)
            if not apk.is_valid_APK():
                self.log.warning(
                    f"APK validation warning for {self.hash.sha256}"
                )
                # Still return the object — partial parsing may still work
        except Exception as e:
            self.log.error(
                f"Format error parsing APK {self.hash.sha256}: {e}"
            )
        return apk

    def _is_valid_apk(self):
        """Check if the APK object was parsed successfully."""
        return self.apk is not None

    def _get_zip_file(self):
        """Get a zipfile.ZipFile handle for direct archive inspection."""
        try:
            return zipfile.ZipFile(self.filepath, 'r')
        except (zipfile.BadZipFile, Exception) as e:
            self.log.error(f"Failed to open APK as ZIP: {e}")
            return None

    def _list_files(self):
        """List all files in the APK archive."""
        if not self._is_valid_apk():
            return []
        try:
            return self.apk.get_files()
        except Exception as e:
            self.log.error(f"Error listing APK files: {e}")
            return []
```

**Key design decisions:**
- The `apk=` parameter allows the ingestor to parse once and share across all APK extractors (same pattern as `pe=` in PEExtractor, `macho=` in MachOExtractor, `elf=` in ELFExtractor)
- `_get_zip_file()` provides direct ZIP access for extractors that need it (resources, native libs, inconsistency tests)
- The androguard `APK` object is the primary parsing interface; `zipfile` is secondary for archive-level inspection

---

## 4. Dataclass Definitions

**File:** `redb/models/dataclasses.py`

Add after the Mach-O dataclasses section. Follow the exact style of existing dataclasses (type annotations, `Optional` for nullable fields, `field(default_factory=list)` for list defaults).

```python
# ============================================================================
# APK Dataclasses
# ============================================================================

@dataclass
class APKFeatures:
    """Core APK metadata and properties."""
    package_name: str
    app_name: str
    version_code: int
    version_name: str
    min_sdk_version: Optional[int] = None
    target_sdk_version: Optional[int] = None
    compile_sdk_version: Optional[int] = None
    main_activity: Optional[str] = None
    is_debuggable: bool = False
    allow_backup: bool = True
    uses_cleartext_traffic: bool = False
    supported_abis: List[str] = field(default_factory=list)
    dex_count: int = 0
    total_dex_size: int = 0
    total_file_count: int = 0
    has_native_code: bool = False
    has_assets: bool = False
    uses_libraries: List[str] = field(default_factory=list)
    earliest_content_modification: Optional[str] = None  # ISO 8601
    latest_content_modification: Optional[str] = None    # ISO 8601
    contains_embedded_apk: bool = False


@dataclass
class APKManifestComponent:
    """Single Android component (activity, service, receiver, provider)."""
    component_type: str      # "activity", "service", "receiver", "provider"
    class_name: str
    is_exported: bool
    intent_actions: List[str] = field(default_factory=list)
    intent_categories: List[str] = field(default_factory=list)


@dataclass
class APKManifest:
    """Full AndroidManifest.xml analysis."""
    activity_count: int
    service_count: int
    receiver_count: int
    provider_count: int
    activities: List[str] = field(default_factory=list)
    services: List[str] = field(default_factory=list)
    receivers: List[str] = field(default_factory=list)
    providers: List[str] = field(default_factory=list)
    exported_components: List[str] = field(default_factory=list)
    intent_filters_by_action: List[str] = field(default_factory=list)
    intent_filters_by_category: List[str] = field(default_factory=list)
    uses_features: List[str] = field(default_factory=list)
    meta_data: Optional[Dict] = None
    manifest_xml: Optional[str] = None  # Full decompiled XML text


@dataclass
class APKPermission:
    """Single permission entry for ClickHouse export."""
    permission_name: str
    protection_level: str    # "normal", "dangerous", "signature", "signatureOrSystem", "unknown"
    is_custom: bool = False  # True if declared by the app itself


@dataclass
class APKPermissions:
    """APK permission summary."""
    total_permission_count: int
    dangerous_permission_count: int
    permissions: List[str] = field(default_factory=list)
    dangerous_permissions: List[str] = field(default_factory=list)
    custom_permissions: List[str] = field(default_factory=list)
    permission_details: List[APKPermission] = field(default_factory=list)
    permhash: Optional[str] = None


@dataclass
class APKCertificate:
    """X.509 certificate from APK signature."""
    subject: str
    issuer: str
    serial_number: str
    valid_from: str
    valid_to: str
    thumbprint_sha1: str
    thumbprint_sha256: str
    algorithm: Optional[str] = None
    key_size: Optional[int] = None
    is_self_signed: bool = False


@dataclass
class APKCodeSigningInfo:
    """Complete APK signing information."""
    _id: str  # sha256
    is_signed: bool
    signature_scheme_versions: List[int] = field(default_factory=list)  # [1], [1,2], [1,2,3], etc.
    number_of_certificates: int = 0
    x509_certificates: Optional[List[APKCertificate]] = None
    signer_subject: Optional[str] = None
    signer_issuer: Optional[str] = None


@dataclass
class APKDexFile:
    """Analysis of a single DEX file."""
    filename: str
    sha256: str
    class_count: int
    method_count: int
    string_count: int
    top_packages: Optional[List[Dict]] = None  # [{"package": str, "class_count": int}]
    api_usage: Optional[Dict[str, List[str]]] = None  # {"reflection": [...], "crypto": [...], ...}
    obfuscation_indicators: Optional[Dict] = None


@dataclass
class APKResource:
    """Embedded resource file entry."""
    path: str
    size: int
    sha256: str
    filetype_magika: str
    is_suspicious: bool = False  # True for executable types


@dataclass
class APKNativeLib:
    """Native .so library entry."""
    abi: str          # e.g., "arm64-v8a"
    filename: str     # e.g., "libfoo.so"
    size: int
    sha256: str
    is_known_packer: bool = False  # True if matches known packer lib name


@dataclass
class APKInconsistencyTests:
    """APK anomaly and anti-analysis detection results."""
    test_zip_bomb: Optional[bool] = None
    test_zip_duplicate_entries: Optional[bool] = None
    test_zip_path_traversal: Optional[bool] = None
    test_zip_suspicious_timestamps: Optional[bool] = None
    test_hidden_dex_files: Optional[bool] = None
    test_manifest_component_mismatch: Optional[bool] = None
    test_debuggable_release: Optional[bool] = None
    test_emulator_detection_strings: Optional[bool] = None
    test_debugger_detection: Optional[bool] = None
    test_root_detection: Optional[bool] = None
```

---

## 5. Tag Enum Updates

**File:** `redb/extractors/enum.py`

Add at the end of the `Tag` class, after the ELF section:

```python
    # APK
    APK_FEATURES = "apk_features"
    APK_MANIFEST = "apk_manifest"
    APK_PERMISSIONS = "apk_permissions"
    APK_SIGNATURE = "apk_signature"
    APK_DEX = "apk_dex"
    APK_RESOURCES = "apk_resources"
    APK_NATIVE_LIBS = "apk_native_libs"
    APK_INCONSISTENCY_TESTS = "apk_inconsistency_tests"
```

---

## 6. Extractor Implementation Details

### 6.1 APKFeaturesExtractor

**File:** `redb/extractors/apk_extractors/apk_features.py`

```python
import inspect
import zipfile
from datetime import datetime, timezone
from typing import Any

from redb.extractors.enum import Tag
from redb.extractors.apk_extractor import APKExtractor
from redb.models.dataclasses import APKFeatures


class APKFeaturesExtractor(APKExtractor):

    def __init__(
        self, filepath, log, exporters=None, index_prefix=None,
        elastic_index=None, known_benign=False, known_malicious=False,
        apk=None,
    ):
        super().__init__(
            filepath, log, exporters, index_prefix,
            elastic_index, known_benign, known_malicious, apk,
        )
        self.apk_features = None
        self.elastic_index = self.index_prefix + "-apk_features"

    def tag(self):
        return Tag.APK_FEATURES.value

    def _extract_zip_timestamps(self):
        """Extract earliest and latest content modification from ZIP entries."""
        # Use zipfile directly for this — androguard doesn't expose ZIP metadata
        earliest = None
        latest = None
        try:
            zf = self._get_zip_file()
            if zf:
                with zf:
                    for info in zf.infolist():
                        try:
                            # date_time is (year, month, day, hour, minute, second)
                            dt = datetime(*info.date_time)
                            if earliest is None or dt < earliest:
                                earliest = dt
                            if latest is None or dt > latest:
                                latest = dt
                        except (ValueError, TypeError):
                            continue
        except Exception as e:
            self.log.warning(f"Error extracting ZIP timestamps: {e}")
        return (
            earliest.isoformat() if earliest else None,
            latest.isoformat() if latest else None,
        )

    def _extract_supported_abis(self):
        """Determine supported ABIs from lib/ directory."""
        abis = set()
        for f in self._list_files():
            if f.startswith("lib/") and f.endswith(".so"):
                parts = f.split("/")
                if len(parts) >= 3:
                    abis.add(parts[1])
        return sorted(abis)

    def _count_dex_files(self):
        """Count DEX files and compute total size."""
        dex_count = 0
        total_size = 0
        try:
            zf = self._get_zip_file()
            if zf:
                with zf:
                    for info in zf.infolist():
                        if info.filename.endswith(".dex"):
                            dex_count += 1
                            total_size += info.file_size
        except Exception as e:
            self.log.warning(f"Error counting DEX files: {e}")
        return dex_count, total_size

    def _check_embedded_apk(self):
        """Check if the archive contains nested APK files."""
        for f in self._list_files():
            if f.lower().endswith(".apk"):
                return True
        return False

    def extract(self):
        try:
            if not self._is_valid_apk():
                self.log.error(f"Invalid APK for {self.hash.sha256}")
                return None

            # Core metadata from androguard
            package_name = self.apk.get_package() or ""
            app_name = self.apk.get_app_name() or ""

            # version_code may be string or int
            try:
                version_code = int(self.apk.get_androidversion_code() or 0)
            except (ValueError, TypeError):
                version_code = 0

            version_name = self.apk.get_androidversion_name() or ""

            # SDK versions
            min_sdk = self.apk.get_min_sdk_version()
            target_sdk = self.apk.get_target_sdk_version()
            # NOTE: compile_sdk may not be available in all androguard versions
            compile_sdk = None
            try:
                compile_sdk = self.apk.get_effective_target_sdk_version()
            except AttributeError:
                pass

            min_sdk = int(min_sdk) if min_sdk else None
            target_sdk = int(target_sdk) if target_sdk else None
            compile_sdk = int(compile_sdk) if compile_sdk else None

            # Main activity
            main_activity = self.apk.get_main_activity()

            # Flags from manifest
            # androguard provides get_attribute_value for manifest attributes
            is_debuggable = self.apk.get_attribute_value(
                "application", "debuggable"
            ) == "true"
            allow_backup = self.apk.get_attribute_value(
                "application", "allowBackup"
            ) != "false"  # default is true
            uses_cleartext = self.apk.get_attribute_value(
                "application", "usesCleartextTraffic"
            ) == "true"

            # Archive-level analysis
            supported_abis = self._extract_supported_abis()
            dex_count, total_dex_size = self._count_dex_files()
            all_files = self._list_files()
            total_file_count = len(all_files)
            has_native_code = any(
                f.startswith("lib/") and f.endswith(".so") for f in all_files
            )
            has_assets = any(f.startswith("assets/") for f in all_files)
            contains_embedded_apk = self._check_embedded_apk()

            # Uses-library
            uses_libraries = []
            try:
                libs = self.apk.get_libraries()
                uses_libraries = list(libs) if libs else []
            except Exception:
                pass

            # ZIP timestamps
            earliest_mod, latest_mod = self._extract_zip_timestamps()

            self.apk_features = APKFeatures(
                package_name=package_name,
                app_name=app_name,
                version_code=version_code,
                version_name=version_name,
                min_sdk_version=min_sdk,
                target_sdk_version=target_sdk,
                compile_sdk_version=compile_sdk,
                main_activity=main_activity,
                is_debuggable=is_debuggable,
                allow_backup=allow_backup,
                uses_cleartext_traffic=uses_cleartext,
                supported_abis=supported_abis,
                dex_count=dex_count,
                total_dex_size=total_dex_size,
                total_file_count=total_file_count,
                has_native_code=has_native_code,
                has_assets=has_assets,
                uses_libraries=uses_libraries,
                earliest_content_modification=earliest_mod,
                latest_content_modification=latest_mod,
                contains_embedded_apk=contains_embedded_apk,
            )
            return self.apk_features

        except Exception as e:
            self.log.error(
                f"Error extracting APK features {self.hash.sha256}: {e}"
            )
            return None

    def prepare_export_data(self, exporter_type: str) -> Any:
        if exporter_type == "ElasticsearchExporter":
            return self.apk_features
        elif exporter_type == "ClickHouseExporter":
            if not self.apk_features:
                return None

            f = self.apk_features
            data = [[
                self.sha256, self.md5, self.sha1,
                f.package_name,
                f.app_name,
                f.version_code,
                f.version_name,
                f.min_sdk_version,
                f.target_sdk_version,
                f.compile_sdk_version,
                f.main_activity,
                int(f.is_debuggable),
                int(f.allow_backup),
                int(f.uses_cleartext_traffic),
                f.supported_abis,
                f.dex_count,
                f.total_dex_size,
                f.total_file_count,
                int(f.has_native_code),
                int(f.has_assets),
                f.uses_libraries,
                f.earliest_content_modification,
                f.latest_content_modification,
                int(f.contains_embedded_apk),
                datetime.now(timezone.utc),
            ]]

            column_names = [
                "sha256", "md5", "sha1",
                "package_name", "app_name", "version_code", "version_name",
                "min_sdk_version", "target_sdk_version", "compile_sdk_version",
                "main_activity",
                "is_debuggable", "allow_backup", "uses_cleartext_traffic",
                "supported_abis",
                "dex_count", "total_dex_size", "total_file_count",
                "has_native_code", "has_assets",
                "uses_libraries",
                "earliest_content_modification", "latest_content_modification",
                "contains_embedded_apk",
                "analysis_date",
            ]

            column_type_names = [
                "FixedString(64)", "FixedString(32)", "FixedString(40)",
                "String", "String", "UInt32", "String",
                "Nullable(UInt16)", "Nullable(UInt16)", "Nullable(UInt16)",
                "Nullable(String)",
                "UInt8", "UInt8", "UInt8",
                "Array(String)",
                "UInt16", "UInt64", "UInt32",
                "UInt8", "UInt8",
                "Array(String)",
                "Nullable(String)", "Nullable(String)",
                "UInt8",
                "DateTime64(3, 'UTC')",
            ]

            return (data, column_names, column_type_names)

    def get_clickhouse_table(self) -> str:
        return "redb_apk_features"
```

### 6.2 APKManifestExtractor

**File:** `redb/extractors/apk_extractors/apk_manifest.py`

**Key androguard API calls:**
```python
# Activities, services, receivers, providers
self.apk.get_activities()       # Returns list of activity class names
self.apk.get_services()         # Returns list of service class names
self.apk.get_receivers()        # Returns list of receiver class names
self.apk.get_providers()        # Returns list of provider class names

# Exported check (per component)
self.apk.get_intent_filters(component_type, component_name)
# Returns dict: {"action": [...], "category": [...]}

# Uses-features
self.apk.get_features()         # Returns list of feature strings

# Full XML
self.apk.get_android_manifest_xml().toxml()
# OR
self.apk.get_android_manifest_axml().get_xml()
```

**Implementation notes:**
- For ClickHouse export of components, use a **one-row-per-component** table (`redb_apk_components`) with columns: `sha256`, `component_type`, `class_name`, `is_exported`, `intent_actions` (Array), `intent_categories` (Array), `analysis_date`
- For the aggregated manifest data (counts, feature list, full XML), use a **one-row-per-APK** table (`redb_apk_manifest`)
- To determine if a component is exported: check `android:exported` attribute. If not explicitly set, it's implicitly exported if the component has intent filters (Android default behavior pre-API 31). From API 31+, `android:exported` must be explicit

### 6.3 APKPermissionsExtractor

**File:** `redb/extractors/apk_extractors/apk_permissions.py`

**Key androguard API calls:**
```python
# Requested permissions
self.apk.get_permissions()              # Returns list of permission strings
self.apk.get_declared_permissions()     # Custom permissions defined by the app

# For protection level, use androguard's permission mapping:
from androguard.core.api_specific_resources import load_permission_mappings
permission_map = load_permission_mappings(target_sdk)
# permission_map[perm_name] -> {"protectionLevel": "dangerous", ...}
```

**Permhash computation:**
```python
import permhash
ph = permhash.permhash_apk(self.filepath)
# Returns SHA-256 hex string
```

**Known dangerous permissions** (reference list for classification fallback):
```python
DANGEROUS_PERMISSIONS = {
    "android.permission.READ_CALENDAR",
    "android.permission.WRITE_CALENDAR",
    "android.permission.CAMERA",
    "android.permission.READ_CONTACTS",
    "android.permission.WRITE_CONTACTS",
    "android.permission.GET_ACCOUNTS",
    "android.permission.ACCESS_FINE_LOCATION",
    "android.permission.ACCESS_COARSE_LOCATION",
    "android.permission.ACCESS_BACKGROUND_LOCATION",
    "android.permission.RECORD_AUDIO",
    "android.permission.READ_PHONE_STATE",
    "android.permission.READ_PHONE_NUMBERS",
    "android.permission.CALL_PHONE",
    "android.permission.ANSWER_PHONE_CALLS",
    "android.permission.ADD_VOICEMAIL",
    "android.permission.USE_SIP",
    "android.permission.BODY_SENSORS",
    "android.permission.SEND_SMS",
    "android.permission.RECEIVE_SMS",
    "android.permission.READ_SMS",
    "android.permission.RECEIVE_WAP_PUSH",
    "android.permission.RECEIVE_MMS",
    "android.permission.READ_EXTERNAL_STORAGE",
    "android.permission.WRITE_EXTERNAL_STORAGE",
    "android.permission.READ_MEDIA_IMAGES",
    "android.permission.READ_MEDIA_VIDEO",
    "android.permission.READ_MEDIA_AUDIO",
    "android.permission.POST_NOTIFICATIONS",
    "android.permission.NEARBY_WIFI_DEVICES",
    "android.permission.ACTIVITY_RECOGNITION",
    "android.permission.BLUETOOTH_SCAN",
    "android.permission.BLUETOOTH_ADVERTISE",
    "android.permission.BLUETOOTH_CONNECT",
}
```

**ClickHouse export:** One row per permission per APK in `redb_apk_permissions`:
- `sha256`, `permission_name`, `protection_level`, `is_custom`, `analysis_date`

The `permhash` value is also stored separately — see Section 8 for integration with `HashExtractor`.

### 6.4 APKSignatureExtractor

**File:** `redb/extractors/apk_extractors/apk_signature.py`

**Key androguard API calls:**
```python
# Get certificate objects
certs = self.apk.get_certificates()     # Returns list of asn1crypto Certificate objects

# For each certificate:
cert.subject.human_friendly              # Subject DN
cert.issuer.human_friendly               # Issuer DN
cert.serial_number                       # Serial
cert.not_valid_before                    # datetime
cert.not_valid_after                     # datetime
cert.hash_algo                           # e.g., "sha256"
cert.signature_algo                      # e.g., "rsassa_pkcs1v15"

# SHA-1 thumbprint
import hashlib
hashlib.sha1(cert.dump()).hexdigest()

# SHA-256 thumbprint
hashlib.sha256(cert.dump()).hexdigest()

# Self-signed check
cert.subject == cert.issuer

# Signature scheme detection:
# v1: Check META-INF/*.SF and META-INF/*.RSA/DSA/EC files exist
# v2/v3: androguard >= 4.x has is_signed_v2() / is_signed_v3()
self.apk.is_signed_v1()
self.apk.is_signed_v2()
self.apk.is_signed_v3()
```

**Implementation notes:**
- Mirror the structure of `PECodeSigningInfo` / `MachOCodeSigningInfo`
- The `_id` field should be `self.sha256` (same as PE/Mach-O signature extractors)

### 6.5 APKDexExtractor

**File:** `redb/extractors/apk_extractors/apk_dex.py`

This is the most complex extractor. Use `androguard.core.dex` for DEX parsing.

**Key androguard API calls:**
```python
from androguard.core.dex import DEX

# Get raw DEX data from APK
dex_files = self.apk.get_all_dex()  # Returns list of raw DEX bytes

for dex_name, dex_data in zip(self.apk.get_dex_names(), dex_files):
    d = DEX(dex_data)

    # Class enumeration
    classes = d.get_classes()
    for cls in classes:
        cls.get_name()          # e.g., "Lcom/example/MainActivity;"

    # Method enumeration
    methods = d.get_methods()
    for method in methods:
        method.get_class_name()  # e.g., "Lcom/example/MainActivity;"
        method.get_name()        # e.g., "onCreate"
        method.get_descriptor()  # e.g., "(Landroid/os/Bundle;)V"

    # String constants
    strings = d.get_strings()    # Returns list of string constants
```

**Computing `top_packages`:**
```python
from collections import Counter

package_counter = Counter()
for cls in classes:
    name = cls.get_name()  # "Lcom/example/foo/Bar;"
    # Convert to package: "com.example.foo"
    parts = name[1:].replace("/", ".").rsplit(".", 1)
    if len(parts) > 1:
        package = parts[0]
    else:
        package = "(default)"
    package_counter[package] += 1

top_packages = [
    {"package": pkg, "class_count": count}
    for pkg, count in package_counter.most_common(20)
]
```

**Computing `api_usage`:**
Iterate over all method cross-references (xrefs) or method invocations. For each invoked method, check if it matches any sensitive API pattern. See Section 12 for the full categorization reference.

```python
api_usage = {cat: [] for cat in SENSITIVE_API_CATEGORIES}

for method in d.get_methods():
    # Get the bytecode and look for invoke-* instructions
    code = method.get_code()
    if not code:
        continue
    # Use androguard's analysis or instruction iteration
    # to find method references that match sensitive patterns
```

**Computing `obfuscation_indicators`:**
```python
class_names = [cls.get_name() for cls in classes]
method_names = [m.get_name() for m in methods if m.get_name() not in ("<init>", "<clinit>")]

short_class = sum(1 for n in class_names if len(n.split("/")[-1].rstrip(";")) <= 2)
short_method = sum(1 for n in method_names if len(n) <= 2)

obfuscation_indicators = {
    "short_class_names_pct": round(short_class / max(len(class_names), 1), 4),
    "short_method_names_pct": round(short_method / max(len(method_names), 1), 4),
    "non_ascii_identifiers": sum(1 for n in class_names if not n.isascii()),
    "avg_class_name_length": round(
        sum(len(n) for n in class_names) / max(len(class_names), 1), 2
    ),
}
```

**ClickHouse export:**
- `redb_apk_dex`: One row per DEX file — `sha256`, `dex_sha256`, `dex_filename`, `class_count`, `method_count`, `string_count`, `top_packages` (JSON string), `obfuscation_indicators` (JSON string), `analysis_date`
- `redb_apk_dex_api_usage`: One row per API category per DEX — `sha256`, `dex_sha256`, `category`, `api_calls` (Array(String)), `analysis_date`

### 6.6 APKResourceExtractor

**File:** `redb/extractors/apk_extractors/apk_resources.py`

**Implementation approach:**
```python
import hashlib
from magika import Magika

magika = Magika()

resources = []
suspicious_files = []

zf = self._get_zip_file()
if zf:
    with zf:
        for info in zf.infolist():
            if info.is_dir():
                continue
            # Only scan res/ and assets/ directories
            if not (info.filename.startswith("res/") or
                    info.filename.startswith("assets/")):
                continue

            data = zf.read(info.filename)
            file_sha256 = hashlib.sha256(data).hexdigest()
            filetype = magika.identify_bytes(data).output.label

            resource = APKResource(
                path=info.filename,
                size=info.file_size,
                sha256=file_sha256,
                filetype_magika=filetype,
            )

            # Flag suspicious file types
            SUSPICIOUS_TYPES = {
                "elf", "pebin", "dex", "apk", "zip", "shell",
                "javascript", "python", "powershell", "batch",
            }
            if filetype in SUSPICIOUS_TYPES:
                resource.is_suspicious = True
                suspicious_files.append(resource)

            resources.append(resource)
```

**ClickHouse export:** One row per resource in `redb_apk_resources`:
- `sha256`, `resource_path`, `resource_size`, `resource_sha256`, `filetype_magika`, `is_suspicious`, `analysis_date`

**Performance note:** For APKs with very large resource directories (some apps have 10K+ files in `res/`), consider limiting to the top N resources by size or only scanning `assets/` fully while sampling `res/`. Document any limits applied.

### 6.7 APKNativeLibExtractor

**File:** `redb/extractors/apk_extractors/apk_native_libs.py`

**Implementation approach:**
```python
native_libs = []
abis = set()

zf = self._get_zip_file()
if zf:
    with zf:
        for info in zf.infolist():
            if info.filename.startswith("lib/") and info.filename.endswith(".so"):
                parts = info.filename.split("/")
                if len(parts) >= 3:
                    abi = parts[1]
                    filename = parts[-1]
                    abis.add(abi)

                    data = zf.read(info.filename)
                    lib_sha256 = hashlib.sha256(data).hexdigest()

                    native_libs.append(APKNativeLib(
                        abi=abi,
                        filename=filename,
                        size=info.file_size,
                        sha256=lib_sha256,
                        is_known_packer=filename in KNOWN_PACKER_LIBS,
                    ))
```

See Section 11 for the `KNOWN_PACKER_LIBS` reference list.

### 6.8 APKInconsistencyTestsExtractor

**File:** `redb/extractors/apk_extractors/apk_inconsistency_tests.py`

Each test is a private method returning `bool`:

```python
def _test_zip_bomb(self):
    """Check if any ZIP entry has compression ratio > 100:1."""
    zf = self._get_zip_file()
    if not zf:
        return None
    with zf:
        for info in zf.infolist():
            if info.compress_size > 0:
                ratio = info.file_size / info.compress_size
                if ratio > 100:
                    return True
    return False

def _test_zip_duplicate_entries(self):
    """Check for duplicate filenames in ZIP directory."""
    zf = self._get_zip_file()
    if not zf:
        return None
    with zf:
        names = [info.filename for info in zf.infolist()]
        return len(names) != len(set(names))

def _test_zip_path_traversal(self):
    """Check for path traversal (../) in ZIP entry names."""
    for f in self._list_files():
        if ".." in f or f.startswith("/"):
            return True
    return False

def _test_zip_suspicious_timestamps(self):
    """Check for timestamps at epoch (1980) or in the future."""
    zf = self._get_zip_file()
    if not zf:
        return None
    now = datetime.now()
    with zf:
        for info in zf.infolist():
            try:
                dt = datetime(*info.date_time)
                if dt.year <= 1980 or dt > now:
                    return True
            except (ValueError, TypeError):
                continue
    return False

def _test_hidden_dex_files(self):
    """Check for DEX files not matching classes*.dex pattern."""
    import re
    standard_pattern = re.compile(r"^classes\d*\.dex$")
    for f in self._list_files():
        if f.endswith(".dex") and not standard_pattern.match(f.split("/")[-1]):
            return True
    return False

def _test_emulator_detection_strings(self):
    """Check for emulator detection patterns in DEX strings."""
    # Inspect DEX strings for known emulator detection indicators
    EMULATOR_INDICATORS = {
        "generic", "sdk", "google_sdk", "Emulator",
        "goldfish", "ranchu", "Andy", "Genymotion",
        "BlueStacks", "nox", "ttVM_Hdragon",
    }
    # Use androguard to extract strings from DEX, then check
    ...

def _test_debugger_detection(self):
    """Check for debugger detection API calls in DEX."""
    # Look for: Debug.isDebuggerConnected, Debug.waitingForDebugger
    ...

def _test_root_detection(self):
    """Check for root detection patterns in DEX."""
    ROOT_INDICATORS = {
        "/system/app/Superuser.apk",
        "/system/xbin/su",
        "/system/bin/su",
        "com.noshufou.android.su",
        "com.thirdparty.superuser",
        "eu.chainfire.supersu",
        "com.koushikdutta.superuser",
        "com.topjohnwu.magisk",
    }
    ...
```

---

## 7. Ingestor Integration

**File:** `redb/ingestor.py`

Replace the stub at line 1668:

```python
elif filetype == "apk":
    logger.debug("APK file detected")
```

With the full dispatch block:

```python
elif filetype == "apk":
    logger.debug("APK file detected")

    # Import APK extractors
    from redb.extractors.apk_extractor import APKExtractor
    from redb.extractors.apk_extractors.apk_features import APKFeaturesExtractor
    from redb.extractors.apk_extractors.apk_manifest import APKManifestExtractor
    from redb.extractors.apk_extractors.apk_permissions import APKPermissionsExtractor
    from redb.extractors.apk_extractors.apk_signature import APKSignatureExtractor
    from redb.extractors.apk_extractors.apk_dex import APKDexExtractor
    from redb.extractors.apk_extractors.apk_resources import APKResourceExtractor
    from redb.extractors.apk_extractors.apk_native_libs import APKNativeLibExtractor
    from redb.extractors.apk_extractors.apk_inconsistency_tests import APKInconsistencyTestsExtractor

    apk_modules = [
        APKFeaturesExtractor,
        APKManifestExtractor,
        APKPermissionsExtractor,
        APKSignatureExtractor,
        APKDexExtractor,
        APKResourceExtractor,
        APKNativeLibExtractor,
        APKInconsistencyTestsExtractor,
    ]

    # Parse APK once with androguard, share across all extractors
    try:
        from androguard.core.apk import APK
        apk = APK(filepath)
    except Exception as e:
        logger.error(f"Failed to parse APK {filepath}: {e}")
        apk = None

    # Run format-agnostic extractors first (same as PE/ELF/MachO)
    # DIE
    if 'all' in selected_modules or 'DIEExtractor' in selected_modules:
        try:
            extractor = DIEExtractor(
                filepath, logger, exporters=exporters,
                index_prefix=index_prefix
            )
            result = extractor.export_data()
            is_packed = bool(result) if result is not None else None
            if result:
                results[ImportResult.CORRECTLY] += 1
            elif result is False:
                results[ImportResult.FAILED] += 1
        except Exception as e:
            logger.error(f"Error in DIEExtractor: {str(e)}")
            results[ImportResult.FAILED] += 1

    # BasicProperties
    if 'all' in selected_modules or 'BasicPropertiesExtractor' in selected_modules:
        try:
            extractor = BasicPropertiesExtractor(
                filepath, logger, exporters=exporters,
                index_prefix=index_prefix
            )
            if is_packed is not None:
                extractor.is_packed = is_packed
            result = extractor.export_data()
            if result:
                results[ImportResult.CORRECTLY] += 1
            elif result is False:
                results[ImportResult.FAILED] += 1
        except Exception as e:
            logger.error(f"Error in BasicPropertiesExtractor: {str(e)}")
            results[ImportResult.FAILED] += 1

    # Hashes
    if 'all' in selected_modules or 'HashExtractor' in selected_modules:
        try:
            extractor = HashExtractor(
                filepath, logger, exporters=exporters,
                index_prefix=index_prefix
            )
            result = extractor.export_data()
            if result:
                results[ImportResult.CORRECTLY] += 1
            elif result is False:
                results[ImportResult.FAILED] += 1
        except Exception as e:
            logger.error(f"Error in HashExtractor: {str(e)}")
            results[ImportResult.FAILED] += 1

    # YARA
    if 'all' in selected_modules or 'YaraExtractor' in selected_modules:
        try:
            extractor = YaraExtractor(
                filepath, logger, exporters=exporters,
                index_prefix=index_prefix
            )
            result = extractor.export_data()
            if result:
                results[ImportResult.CORRECTLY] += 1
            elif result is False:
                results[ImportResult.FAILED] += 1
        except Exception as e:
            logger.error(f"Error in YaraExtractor: {str(e)}")
            results[ImportResult.FAILED] += 1

    # APK-specific extractors
    for module in apk_modules:
        if 'all' in selected_modules or module.__name__ in selected_modules:
            try:
                logger.debug(f"Running {module.__name__}")
                extractor = module(
                    filepath,
                    logger,
                    exporters=exporters,
                    index_prefix=index_prefix,
                    apk=apk
                )
                result = extractor.export_data()
                if result:
                    results[ImportResult.CORRECTLY] += 1
                elif result is False:
                    results[ImportResult.FAILED] += 1
            except Exception as e:
                logger.error(f"Error in {module.__name__}: {str(e)}")
                results[ImportResult.FAILED] += 1
```

**Note:** Follow the exact error-handling and `selected_modules` check pattern used by the existing PE/ELF/Mach-O dispatch blocks. The code above mirrors the pattern from `ingestor.py:1540-1666`.

---

## 8. Hashes Dataclass Update

**File:** `redb/models/dataclasses.py`

Add to the `Hashes` dataclass after the existing Mach-O hashes:

```python
@dataclass
class Hashes:
    md5: str
    sha1: str
    sha256: str
    ssdeep_hash: str
    tlsh_hash: str
    authentihash: Optional[str] = None  # PE
    imphash: Optional[str] = None  # PE
    impfuzzy: Optional[str] = None  # PE TODO: implement
    typerefhash: Optional[str] = None  # DotNet
    richhash: Optional[str] = None  # PE
    richpe_hash: Optional[str] = None  # PE
    richpv_hash: Optional[str] = None  # PE
    richpv_hash_sorted: Optional[str] = None  # PE
    import_hash: Optional[str] = None  # ELF
    export_hash: Optional[str] = None  # ELF
    section_hash: Optional[str] = None  # ELF
    symbol_hash: Optional[str] = None  # ELF (symhash)
    dynamic_hash: Optional[str] = None  # ELF
    # Mach-O similarity hashes
    macho_dylib_hash: Optional[str] = None
    macho_import_hash: Optional[str] = None
    macho_export_hash: Optional[str] = None
    macho_entitlement_hash: Optional[str] = None
    macho_symhash: Optional[str] = None
    # APK similarity hashes
    permhash: Optional[str] = None  # APK: SHA-256 of sorted permissions (Mandiant/Google)
```

The `permhash` should be computed in `HashExtractor` when the filetype is APK, using the `permhash` library:

```python
# In HashExtractor, when filetype == "apk":
import permhash as permhash_lib
self.hashes.permhash = permhash_lib.permhash_apk(self.filepath)
```

The `permhash` column must be added to the existing `redb_hashes` table:

```sql
ALTER TABLE redb_hashes
    ADD COLUMN IF NOT EXISTS permhash Nullable(FixedString(64));
```

---

## 9. ClickHouse Schema

Create the following tables. Naming convention follows existing tables (`redb_pe_features`, `redb_elf_features`, etc.):

```sql
-- Core metadata (one row per APK)
CREATE TABLE redb_apk_features (
    sha256              FixedString(64),
    md5                 FixedString(32),
    sha1                FixedString(40),
    package_name        String,
    app_name            String,
    version_code        UInt32,
    version_name        String,
    min_sdk_version     Nullable(UInt16),
    target_sdk_version  Nullable(UInt16),
    compile_sdk_version Nullable(UInt16),
    main_activity       Nullable(String),
    is_debuggable       UInt8,
    allow_backup        UInt8,
    uses_cleartext_traffic UInt8,
    supported_abis      Array(String),
    dex_count           UInt16,
    total_dex_size      UInt64,
    total_file_count    UInt32,
    has_native_code     UInt8,
    has_assets          UInt8,
    uses_libraries      Array(String),
    earliest_content_modification Nullable(String),
    latest_content_modification   Nullable(String),
    contains_embedded_apk UInt8,
    analysis_date       DateTime64(3, 'UTC')
) ENGINE = ReplacingMergeTree()
ORDER BY sha256;

-- Manifest components (one row per component)
CREATE TABLE redb_apk_components (
    sha256              FixedString(64),
    component_type      LowCardinality(String),  -- "activity", "service", "receiver", "provider"
    class_name          String,
    is_exported         UInt8,
    intent_actions      Array(String),
    intent_categories   Array(String),
    analysis_date       DateTime64(3, 'UTC')
) ENGINE = ReplacingMergeTree()
ORDER BY (sha256, component_type, class_name);

-- Manifest summary (one row per APK)
CREATE TABLE redb_apk_manifest (
    sha256              FixedString(64),
    md5                 FixedString(32),
    sha1                FixedString(40),
    activity_count      UInt16,
    service_count       UInt16,
    receiver_count      UInt16,
    provider_count      UInt16,
    intent_filters_by_action   Array(String),
    intent_filters_by_category Array(String),
    uses_features       Array(String),
    manifest_xml        Nullable(String),
    analysis_date       DateTime64(3, 'UTC')
) ENGINE = ReplacingMergeTree()
ORDER BY sha256;

-- Permissions (one row per permission per APK)
CREATE TABLE redb_apk_permissions (
    sha256              FixedString(64),
    permission_name     String,
    protection_level    LowCardinality(String),
    is_custom           UInt8,
    analysis_date       DateTime64(3, 'UTC')
) ENGINE = ReplacingMergeTree()
ORDER BY (sha256, permission_name);

-- Signing info (one row per APK)
CREATE TABLE redb_apk_signature (
    sha256              FixedString(64),
    md5                 FixedString(32),
    sha1                FixedString(40),
    is_signed           UInt8,
    signature_scheme_versions Array(UInt8),
    number_of_certificates UInt8,
    signer_subject      Nullable(String),
    signer_issuer       Nullable(String),
    analysis_date       DateTime64(3, 'UTC')
) ENGINE = ReplacingMergeTree()
ORDER BY sha256;

-- Certificate details (one row per certificate per APK)
CREATE TABLE redb_apk_certificates (
    sha256              FixedString(64),
    subject             String,
    issuer              String,
    serial_number       String,
    valid_from          String,
    valid_to            String,
    thumbprint_sha1     FixedString(40),
    thumbprint_sha256   FixedString(64),
    algorithm           Nullable(String),
    key_size            Nullable(UInt16),
    is_self_signed      UInt8,
    analysis_date       DateTime64(3, 'UTC')
) ENGINE = ReplacingMergeTree()
ORDER BY (sha256, thumbprint_sha256);

-- DEX file analysis (one row per DEX file)
CREATE TABLE redb_apk_dex (
    sha256              FixedString(64),
    dex_sha256          FixedString(64),
    dex_filename        String,
    dex_tlsh            Nullable(String),
    class_count         UInt32,
    method_count        UInt32,
    string_count        UInt32,
    top_packages        String,       -- JSON
    obfuscation_indicators String,    -- JSON
    analysis_date       DateTime64(3, 'UTC')
) ENGINE = ReplacingMergeTree()
ORDER BY (sha256, dex_sha256);

-- DEX API usage (one row per category per DEX)
CREATE TABLE redb_apk_dex_api_usage (
    sha256              FixedString(64),
    dex_sha256          FixedString(64),
    category            LowCardinality(String),
    api_calls           Array(String),
    analysis_date       DateTime64(3, 'UTC')
) ENGINE = ReplacingMergeTree()
ORDER BY (sha256, dex_sha256, category);

-- Resource inventory (one row per resource)
CREATE TABLE redb_apk_resources (
    sha256              FixedString(64),
    resource_path       String,
    resource_size       UInt64,
    resource_sha256     FixedString(64),
    filetype_magika     LowCardinality(String),
    is_suspicious       UInt8,
    analysis_date       DateTime64(3, 'UTC')
) ENGINE = ReplacingMergeTree()
ORDER BY (sha256, resource_path);

-- Native libraries (one row per .so file)
CREATE TABLE redb_apk_native_libs (
    sha256              FixedString(64),
    abi                 LowCardinality(String),
    filename            String,
    size                UInt64,
    lib_sha256          FixedString(64),
    is_known_packer     UInt8,
    analysis_date       DateTime64(3, 'UTC')
) ENGINE = ReplacingMergeTree()
ORDER BY (sha256, abi, filename);

-- Inconsistency tests (one row per APK)
CREATE TABLE redb_apk_inconsistency_tests (
    sha256              FixedString(64),
    md5                 FixedString(32),
    sha1                FixedString(40),
    test_zip_bomb                    Nullable(UInt8),
    test_zip_duplicate_entries       Nullable(UInt8),
    test_zip_path_traversal          Nullable(UInt8),
    test_zip_suspicious_timestamps   Nullable(UInt8),
    test_hidden_dex_files            Nullable(UInt8),
    test_manifest_component_mismatch Nullable(UInt8),
    test_debuggable_release          Nullable(UInt8),
    test_emulator_detection_strings  Nullable(UInt8),
    test_debugger_detection          Nullable(UInt8),
    test_root_detection              Nullable(UInt8),
    analysis_date       DateTime64(3, 'UTC')
) ENGINE = ReplacingMergeTree()
ORDER BY sha256;
```

---

## 10. Androguard API Reference

Quick reference for the most commonly used androguard APIs. Full docs: https://androguard.readthedocs.io/

### APK class (`androguard.core.apk.APK`)

| Method | Returns | Description |
|--------|---------|-------------|
| `APK(filepath)` | `APK` | Parse an APK file |
| `.is_valid_APK()` | `bool` | Check if parsing succeeded |
| `.get_package()` | `str` | Package name |
| `.get_app_name()` | `str` | Application display name |
| `.get_androidversion_code()` | `str` | Version code |
| `.get_androidversion_name()` | `str` | Version name |
| `.get_min_sdk_version()` | `str` | Minimum SDK |
| `.get_target_sdk_version()` | `str` | Target SDK |
| `.get_main_activity()` | `str` | Main/launcher activity |
| `.get_activities()` | `list[str]` | All activity class names |
| `.get_services()` | `list[str]` | All service class names |
| `.get_receivers()` | `list[str]` | All receiver class names |
| `.get_providers()` | `list[str]` | All provider class names |
| `.get_permissions()` | `list[str]` | Requested permissions |
| `.get_declared_permissions()` | `list[str]` | Custom-defined permissions |
| `.get_features()` | `list[str]` | Uses-feature declarations |
| `.get_libraries()` | `list[str]` | Uses-library declarations |
| `.get_files()` | `list[str]` | All files in the APK |
| `.get_certificates()` | `list[Certificate]` | X.509 certificate objects |
| `.get_all_dex()` | `list[bytes]` | Raw DEX file contents |
| `.get_dex_names()` | `list[str]` | DEX filenames |
| `.is_signed_v1()` | `bool` | JAR signature present |
| `.is_signed_v2()` | `bool` | v2 signature present |
| `.is_signed_v3()` | `bool` | v3 signature present |
| `.get_attribute_value(tag, attr)` | `str` | Get manifest attribute |
| `.get_android_manifest_xml()` | `minidom` | Parsed manifest XML |
| `.get_intent_filters(type, name)` | `dict` | Intent filters for component |

### DEX class (`androguard.core.dex.DEX`)

| Method | Returns | Description |
|--------|---------|-------------|
| `DEX(raw_bytes)` | `DEX` | Parse raw DEX data |
| `.get_classes()` | `list[ClassDefItem]` | All class definitions |
| `.get_methods()` | `list[EncodedMethod]` | All methods |
| `.get_strings()` | `list[str]` | All string constants |

---

## 11. Known Packer/Protector Signatures

Native library names commonly associated with packers and protectors. Used by `APKNativeLibExtractor` to flag `is_known_packer`:

```python
KNOWN_PACKER_LIBS = {
    # Jiagu (360/Qihoo)
    "libjiagu.so", "libjiagu_a64.so", "libjiagu_x86.so", "libjiagu_x64.so",
    # Bangcle/SecNeo
    "libsecexe.so", "libsecmain.so", "libSecShell.so",
    # Baidu
    "libbaiduprotect.so",
    # Tencent (Legu)
    "libshell-super.2019.so", "libshella-*.so", "libtxAppProtect.so",
    "libBugly.so", "mix.dex",
    # iJiami
    "libexec.so", "libexecmain.so",
    # Alibaba
    "libmobisec.so", "libaliprotect.so",
    # APKProtect
    "libAPKProtect.so",
    # Pangxie (Pangolin)
    "libdexjni.so",
    # DexProtector
    "libdexprotector.so",
    # AppSolid
    "libAppSolid.so",
    # Kiwisec
    "libkwscmm.so",
    # DingXiang
    "libx3g.so",
    # NQ Shield
    "libnqshield.so",
    # Generic / other
    "libprotectClass.so",
    "libDexHelper.so",
    "libdexloader.so",
    "libfdog.so",
}
```

**Note:** This list should be maintained and expanded over time. For glob-style matching (e.g., `libshella-*.so`), use `fnmatch` instead of exact set lookup.

---

## 12. Sensitive API Categorization Reference

Used by `APKDexExtractor` to categorize API calls. Each category maps to a list of class/method patterns:

```python
SENSITIVE_API_CATEGORIES = {
    "reflection": [
        "Ljava/lang/reflect/Method;->invoke",
        "Ljava/lang/reflect/Field;->get",
        "Ljava/lang/reflect/Field;->set",
        "Ljava/lang/reflect/Constructor;->newInstance",
        "Ljava/lang/Class;->forName",
        "Ljava/lang/Class;->getMethod",
        "Ljava/lang/Class;->getDeclaredMethod",
        "Ljava/lang/Class;->getDeclaredField",
        "Ljava/lang/ClassLoader;->loadClass",
    ],
    "crypto": [
        "Ljavax/crypto/Cipher;->getInstance",
        "Ljavax/crypto/Cipher;->init",
        "Ljavax/crypto/spec/SecretKeySpec;-><init>",
        "Ljavax/crypto/spec/IvParameterSpec;-><init>",
        "Ljava/security/MessageDigest;->getInstance",
        "Ljava/security/KeyStore;->getInstance",
        "Ljavax/crypto/Mac;->getInstance",
    ],
    "dynamic_loading": [
        "Ldalvik/system/DexClassLoader;-><init>",
        "Ldalvik/system/PathClassLoader;-><init>",
        "Ldalvik/system/InMemoryDexClassLoader;-><init>",
        "Ldalvik/system/BaseDexClassLoader;-><init>",
        "Ljava/lang/Runtime;->exec",
        "Ljava/lang/ProcessBuilder;->start",
    ],
    "telephony": [
        "Landroid/telephony/TelephonyManager;->getDeviceId",
        "Landroid/telephony/TelephonyManager;->getSubscriberId",
        "Landroid/telephony/TelephonyManager;->getLine1Number",
        "Landroid/telephony/TelephonyManager;->getSimSerialNumber",
        "Landroid/telephony/TelephonyManager;->getNetworkOperator",
        "Landroid/telephony/TelephonyManager;->getSimOperator",
    ],
    "sms": [
        "Landroid/telephony/SmsManager;->sendTextMessage",
        "Landroid/telephony/SmsManager;->sendMultipartTextMessage",
        "Landroid/telephony/SmsManager;->sendDataMessage",
    ],
    "network": [
        "Ljava/net/HttpURLConnection;->connect",
        "Ljava/net/URL;->openConnection",
        "Lokhttp3/OkHttpClient;-><init>",
        "Lokhttp3/Request$Builder;->build",
        "Lorg/apache/http/client/HttpClient;->execute",
        "Landroid/webkit/WebView;->loadUrl",
        "Landroid/webkit/WebView;->setWebViewClient",
    ],
    "native": [
        "Ljava/lang/System;->loadLibrary",
        "Ljava/lang/System;->load",
        "Ljava/lang/Runtime;->loadLibrary",
    ],
    "device_info": [
        "Landroid/os/Build;->FINGERPRINT",
        "Landroid/os/Build;->MODEL",
        "Landroid/os/Build;->MANUFACTURER",
        "Landroid/os/Build;->PRODUCT",
        "Landroid/os/Build;->BRAND",
        "Landroid/os/Build;->DEVICE",
        "Landroid/os/Build;->HARDWARE",
        "Landroid/os/Build;->SERIAL",
        "Landroid/os/Build$VERSION;->SDK_INT",
        "Landroid/provider/Settings$Secure;->getString",  # ANDROID_ID
    ],
    "file_io": [
        "Ljava/io/FileOutputStream;-><init>",
        "Ljava/io/FileInputStream;-><init>",
        "Landroid/content/SharedPreferences;->edit",
        "Landroid/database/sqlite/SQLiteDatabase;->execSQL",
        "Landroid/database/sqlite/SQLiteDatabase;->rawQuery",
    ],
    "ipc": [
        "Landroid/content/ContentResolver;->query",
        "Landroid/content/ContentResolver;->insert",
        "Landroid/content/ContentResolver;->delete",
        "Landroid/content/Intent;-><init>",
        "Landroid/content/Context;->sendBroadcast",
        "Landroid/content/Context;->startService",
        "Landroid/content/Context;->bindService",
    ],
}
```

**Matching approach:** For each method invocation found in DEX bytecode, check if its full signature (class + method) starts with any of the patterns above. Store only the first match per unique API call (avoid duplicates from multiple call sites).

---

## Implementation Checklist

- [ ] Add `androguard` and `permhash` to `requirements.txt`
- [ ] Create `redb/extractors/apk_extractor.py` (base class)
- [ ] Create `redb/extractors/apk_extractors/__init__.py`
- [ ] Implement `APKFeaturesExtractor`
- [ ] Implement `APKManifestExtractor`
- [ ] Implement `APKPermissionsExtractor`
- [ ] Implement `APKSignatureExtractor`
- [ ] Implement `APKDexExtractor`
- [ ] Implement `APKResourceExtractor`
- [ ] Implement `APKNativeLibExtractor`
- [ ] Implement `APKInconsistencyTestsExtractor`
- [ ] Add APK tags to `redb/extractors/enum.py`
- [ ] Add APK dataclasses to `redb/models/dataclasses.py`
- [ ] Add `permhash` field to `Hashes` dataclass
- [ ] Wire up APK dispatch in `redb/ingestor.py`
- [ ] Integrate `permhash` computation in `HashExtractor`
- [ ] Create ClickHouse migration scripts for new tables
- [ ] Unit tests per extractor
- [ ] Integration test: full APK ingestion pipeline
- [ ] Cross-validate output against VirusTotal for reference samples