# analyzing-android-malware-with-apktool

Perform static analysis of Android APK malware using apktool for resource decompilation, jadx for Java source recovery, and androguard for manifest inspection, dangerous permission-combination detection, and identification of obfuscated code, dynamic code loading, and reflection-based API calls. Use to statically triage a suspicious APK without executing it or to build mobile malware detection rules.

- **Kind:** skill
- **Source:** https://github.com/mukul975/Anthropic-Cybersecurity-Skills
- **Page:** https://forefy.com/skills/807b5675-3085-41e8-a683-c2790528d63b
- **API (JSON + files):** https://forefy.com/api/asr/807b5675-3085-41e8-a683-c2790528d63b

---

## LICENSE

```

```

## SKILL.md

---
name: analyzing-android-malware-with-apktool
description: Perform static analysis of Android APK malware using apktool for resource decompilation, jadx for Java source recovery, and androguard for manifest inspection, dangerous permission-combination detection, and identification of obfuscated code, dynamic code loading, and reflection-based API calls. Use to statically triage a suspicious APK without executing it or to build mobile malware detection rules.
domain: cybersecurity
subdomain: malware-analysis
tags:
- Android
- APK
- apktool
- jadx
- androguard
- mobile-malware
- static-analysis
- reverse-engineering
version: '1.0'
author: mahipal
license: Apache-2.0
nist_csf:
- DE.AE-02
- RS.AN-03
- ID.RA-01
- DE.CM-01
mitre_attack:
- T1406
- T1407
- T1626.001
- T1655.001
- T1521.001
---

# Analyzing Android Malware with Apktool

## Overview

Android malware distributed as APK files can be statically analyzed to extract permissions, activities, services, broadcast receivers, and suspicious API calls without executing the sample. This skill uses androguard for programmatic APK analysis, identifying dangerous permission combinations, obfuscated code patterns, dynamic code loading, reflection-based API calls, and network communication indicators.


## When to Use

- When investigating security incidents that require analyzing android malware with apktool
- When building detection rules or threat hunting queries for this domain
- When SOC analysts need structured procedures for this analysis type
- When validating security monitoring coverage for related attack techniques

## Prerequisites

- Python 3.9+ with `androguard`
- apktool (for resource decompilation)
- jadx (for Java source recovery, optional)
- Isolated analysis environment (VM or sandbox)
- Sample APK files for analysis

## Steps

1. Parse APK with androguard to extract manifest metadata
2. Enumerate requested permissions and flag dangerous combinations
3. List activities, services, receivers, and providers from manifest
4. Scan for suspicious API calls (reflection, crypto, SMS, telephony)
5. Detect dynamic code loading patterns (DexClassLoader, Runtime.exec)
6. Extract hardcoded URLs, IPs, and C2 indicators from strings
7. Generate risk assessment report with MITRE ATT&CK mobile mappings

## Expected Output

- JSON report with permission analysis, component listing, suspicious API calls, network indicators, and risk score
- Extracted strings and potential IOCs from the APK

## references

```

```

## references/api-reference.md

# API Reference — Analyzing Android Malware with Apktool

## Libraries Used
- **androguard**: Python APK/DEX analysis — `AnalyzeAPK()`, permission enumeration, API call scanning
- **re**: Regex extraction of URLs, IPs, base64 patterns from DEX strings
- **json**: JSON serialization for analysis reports

## CLI Interface
```
python agent.py sample.apk permissions
python agent.py sample.apk manifest
python agent.py sample.apk apis
python agent.py sample.apk strings
python agent.py sample.apk full
python agent.py sample.apk           # defaults to full analysis
```

## Core Functions

### `analyze_permissions(apk)` — Permission risk assessment
Calls `apk.get_permissions()`. Flags 20 dangerous permissions including
SEND_SMS, READ_CONTACTS, BIND_DEVICE_ADMIN, BIND_ACCESSIBILITY_SERVICE.
Risk: CRITICAL >= 8 dangerous, HIGH >= 5, MEDIUM >= 2, LOW < 2.

### `analyze_manifest(apk)` — Manifest component extraction
Calls `apk.get_activities()`, `get_services()`, `get_receivers()`, `get_providers()`.
Returns package name, version, SDK levels, and all component lists.

### `scan_suspicious_apis(dx)` — Suspicious API call detection
Searches DEX analysis for 14 patterns including:
- `Runtime.exec`, `ProcessBuilder.start` — command execution
- `DexClassLoader.loadClass` — dynamic code loading
- `Method.invoke`, `Class.forName` — reflection
- `Cipher.getInstance` — cryptographic operations
- `SmsManager.sendTextMessage` — SMS abuse

### `extract_strings(dx, apk)` — IOC extraction from DEX strings
Regex extraction of HTTP/HTTPS URLs, external IP addresses, and base64 strings.
Filters out private IP ranges (10.x, 192.168.x, 172.16.x, 127.x).

### `detect_obfuscation(apk, dx)` — Obfuscation indicator detection
Checks for single-letter class names (ProGuard), multi-DEX, native libraries.

### `full_analysis(apk_path)` — Comprehensive malware assessment

## Androguard API
| Method | Returns |
|--------|---------|
| `AnalyzeAPK(path)` | `(APK, list[DEX], Analysis)` tuple |
| `apk.get_permissions()` | List of Android permissions |
| `apk.get_activities()` | Activity component names |
| `apk.get_services()` | Service component names |
| `apk.get_receivers()` | BroadcastReceiver names |
| `apk.get_package()` | Package name string |
| `dx.find_methods(classname, methodname)` | Matching method analysis objects |
| `dx.get_strings()` | All strings from DEX files |
| `dx.get_classes()` | All class analysis objects |

## Risk Scoring
| Factor | Max Points |
|--------|-----------|
| Dangerous permissions (8 pts each) | 40 |
| Suspicious API calls (10 pts each) | 30 |
| External IPs (5 pts each) | 15 |
| Obfuscation detected | 15 |

## Dependencies
- `androguard` >= 3.4.0
- Isolated analysis environment recommended

## scripts

```

```

## scripts/agent.py

```python
#!/usr/bin/env python3
"""Agent for static analysis of Android APK malware using androguard."""

import json
import re
import argparse
from datetime import datetime

try:
    from androguard.core.apk import APK
    from androguard.core.dex import DEX
    from androguard.misc import AnalyzeAPK
except ImportError:
    APK = None
    AnalyzeAPK = None

DANGEROUS_PERMISSIONS = [
    "android.permission.SEND_SMS", "android.permission.READ_SMS",
    "android.permission.RECEIVE_SMS", "android.permission.READ_CONTACTS",
    "android.permission.READ_CALL_LOG", "android.permission.RECORD_AUDIO",
    "android.permission.CAMERA", "android.permission.ACCESS_FINE_LOCATION",
    "android.permission.READ_PHONE_STATE", "android.permission.CALL_PHONE",
    "android.permission.WRITE_EXTERNAL_STORAGE", "android.permission.READ_EXTERNAL_STORAGE",
    "android.permission.INSTALL_PACKAGES", "android.permission.REQUEST_INSTALL_PACKAGES",
    "android.permission.SYSTEM_ALERT_WINDOW", "android.permission.BIND_ACCESSIBILITY_SERVICE",
    "android.permission.BIND_DEVICE_ADMIN", "android.permission.RECEIVE_BOOT_COMPLETED",
    "android.permission.WRITE_SETTINGS", "android.permission.CHANGE_WIFI_STATE",
]

SUSPICIOUS_API_PATTERNS = [
    r"Ljava/lang/Runtime;->exec",
    r"Ljava/lang/ProcessBuilder;->start",
    r"Ldalvik/system/DexClassLoader;->loadClass",
    r"Ljava/lang/reflect/Method;->invoke",
    r"Ljava/lang/Class;->forName",
    r"Ljavax/crypto/Cipher;->getInstance",
    r"Landroid/telephony/SmsManager;->sendTextMessage",
    r"Landroid/app/admin/DevicePolicyManager;->lockNow",
    r"Landroid/content/pm/PackageManager;->setComponentEnabledSetting",
    r"Ljava/net/HttpURLConnection;->connect",
    r"Lokhttp3/OkHttpClient;->newCall",
    r"Landroid/webkit/WebView;->loadUrl",
    r"Landroid/os/Build;->SERIAL",
    r"Landroid/provider/Settings\$Secure;->getString",
]


def analyze_permissions(apk):
    """Analyze requested permissions and flag dangerous ones."""
    permissions = apk.get_permissions()
    dangerous = [p for p in permissions if p in DANGEROUS_PERMISSIONS]
    return {
        "total_permissions": len(permissions),
        "permissions": permissions,
        "dangerous_permissions": dangerous,
        "dangerous_count": len(dangerous),
        "permission_risk": "CRITICAL" if len(dangerous) >= 8 else "HIGH" if len(dangerous) >= 5 else "MEDIUM" if len(dangerous) >= 2 else "LOW",
    }


def analyze_manifest(apk):
    """Extract manifest components: activities, services, receivers, providers."""
    activities = apk.get_activities()
    services = apk.get_services()
    receivers = apk.get_receivers()
    providers = apk.get_providers()
    return {
        "package_name": apk.get_package(),
        "app_name": apk.get_app_name(),
        "version_name": apk.get_androidversion_name(),
        "version_code": apk.get_androidversion_code(),
        "min_sdk": apk.get_min_sdk_version(),
        "target_sdk": apk.get_target_sdk_version(),
        "activities": list(activities),
        "services": list(services),
        "receivers": list(receivers),
        "providers": list(providers),
        "activity_count": len(activities),
        "service_count": len(services),
        "receiver_count": len(receivers),
        "provider_count": len(providers),
    }


def scan_suspicious_apis(dx):
    """Scan DEX analysis for suspicious API calls."""
    findings = []
    if not dx:
        return findings
    for pattern in SUSPICIOUS_API_PATTERNS:
        class_name = pattern.split(";->")[0] + ";"
        method_name = pattern.split(";->")[1] if ";->" in pattern else None
        for method in dx.find_methods(classname=class_name, methodname=method_name):
            xrefs = list(method.get_xref_from())
            if xrefs:
                findings.append({
                    "api": pattern,
                    "callers": len(xrefs),
                    "first_caller_class": str(xrefs[0][0].name) if xrefs else None,
                })
    return findings


def extract_strings(dx, apk):
    """Extract suspicious strings: URLs, IPs, base64 patterns."""
    url_pattern = re.compile(r'https?://[\w\-._~:/?#\[\]@!$&\'()*+,;=]+', re.IGNORECASE)
    ip_pattern = re.compile(r'\b(?:\d{1,3}\.){3}\d{1,3}\b')
    b64_pattern = re.compile(r'[A-Za-z0-9+/]{30,}={0,2}')

    urls = set()
    ips = set()
    b64_strings = []

    if dx:
        for s in dx.get_strings():
            val = str(s)
            urls.update(url_pattern.findall(val))
            ips.update(ip_pattern.findall(val))
            b64_matches = b64_pattern.findall(val)
            b64_strings.extend(b64_matches[:5])

    private_ips = {"10.", "192.168.", "172.16.", "127.0."}
    external_ips = [ip for ip in ips if not any(ip.startswith(p) for p in private_ips)]

    return {
        "urls": sorted(urls)[:30],
        "external_ips": sorted(external_ips)[:20],
        "suspicious_base64": b64_strings[:10],
        "url_count": len(urls),
        "external_ip_count": len(external_ips),
    }


def detect_obfuscation(apk, dx):
    """Detect code obfuscation indicators."""
    indicators = []
    if dx:
        short_class_names = 0
        for cls in dx.get_classes():
            name = str(cls.name)
            parts = name.replace("/", ".").split(".")
            if any(len(p) == 1 and p.isalpha() for p in parts):
                short_class_names += 1
        if short_class_names > 10:
            indicators.append({"type": "single_letter_classes", "count": short_class_names})

    dex_files = [f for f in apk.get_files() if f.endswith(".dex")]
    if len(dex_files) > 1:
        indicators.append({"type": "multi_dex", "dex_count": len(dex_files)})

    native_libs = [f for f in apk.get_files() if f.endswith(".so")]
    if native_libs:
        indicators.append({"type": "native_libraries", "libs": native_libs[:10]})

    return {
        "obfuscation_indicators": indicators,
        "likely_obfuscated": len(indicators) > 0,
    }


def full_analysis(apk_path):
    """Run comprehensive APK malware analysis."""
    if not APK or not AnalyzeAPK:
        return {"error": "androguard not installed: pip install androguard"}

    a, d, dx = AnalyzeAPK(apk_path)

    perm_analysis = analyze_permissions(a)
    manifest = analyze_manifest(a)
    suspicious_apis = scan_suspicious_apis(dx)
    strings = extract_strings(dx, a)
    obfuscation = detect_obfuscation(a, dx)

    risk_score = 0
    risk_score += min(perm_analysis["dangerous_count"] * 8, 40)
    risk_score += min(len(suspicious_apis) * 10, 30)
    risk_score += min(strings["external_ip_count"] * 5, 15)
    risk_score += 15 if obfuscation["likely_obfuscated"] else 0
    risk_score = min(risk_score, 100)

    return {
        "analysis_type": "Android APK Static Analysis",
        "timestamp": datetime.utcnow().isoformat(),
        "file": apk_path,
        "manifest": manifest,
        "permissions": perm_analysis,
        "suspicious_apis": suspicious_apis[:20],
        "strings": strings,
        "obfuscation": obfuscation,
        "risk_score": risk_score,
        "risk_level": "CRITICAL" if risk_score >= 70 else "HIGH" if risk_score >= 50 else "MEDIUM" if risk_score >= 25 else "LOW",
        "mitre_techniques": [
            {"id": "T1418", "name": "Software Discovery"} if manifest["service_count"] > 5 else None,
            {"id": "T1417", "name": "Input Capture"} if "android.permission.BIND_ACCESSIBILITY_SERVICE" in perm_analysis["permissions"] else None,
            {"id": "T1582", "name": "SMS Control"} if "android.permission.SEND_SMS" in perm_analysis["permissions"] else None,
            {"id": "T1404", "name": "Exploitation for Privilege Escalation"} if any("DevicePolicyManager" in a.get("api", "") for a in suspicious_apis) else None,
        ],
    }


def main():
    parser = argparse.ArgumentParser(description="Android APK Malware Analysis Agent")
    parser.add_argument("apk", help="Path to APK file")
    sub = parser.add_subparsers(dest="command")
    sub.add_parser("permissions", help="Analyze permissions")
    sub.add_parser("manifest", help="Extract manifest components")
    sub.add_parser("apis", help="Scan for suspicious API calls")
    sub.add_parser("strings", help="Extract URLs, IPs, and encoded strings")
    sub.add_parser("full", help="Full malware analysis")
    args = parser.parse_args()

    if args.command == "full" or args.command is None:
        result = full_analysis(args.apk)
    else:
        a, d, dx = AnalyzeAPK(args.apk)
        if args.command == "permissions":
            result = analyze_permissions(a)
        elif args.command == "manifest":
            result = analyze_manifest(a)
        elif args.command == "apis":
            result = scan_suspicious_apis(dx)
        elif args.command == "strings":
            result = extract_strings(dx, a)
    print(json.dumps(result, indent=2, default=str))


if __name__ == "__main__":
    main()
```