Security Skills Atlas
malware analysis

Analyzing Android Malware with Apktool

Perform static analysis of Android APK malware samples using apktool for decompilation, jadx for Java source recovery, and androguard for permission analysis, manifest inspection, and suspicious API call detection.

androguardandroidapkapktooljadxmobile-malwarereverse-engineeringstatic-analysis
Install this skill
npx skills add mukul975/Anthropic-Cybersecurity-Skills
Framework mappings

MITRE ATT&CK

T1406 on the official MITRE ATT&CK siteT1407 on the official MITRE ATT&CK siteT1521.001 on the official MITRE ATT&CK siteT1626.001 on the official MITRE ATT&CK siteT1655.001 on the official MITRE ATT&CK site

NIST CSF 2.0

DE.AE-02 on the official NIST CSF 2.0 siteDE.CM-01 on the official NIST CSF 2.0 siteID.RA-01 on the official NIST CSF 2.0 siteRS.AN-03 on the official NIST CSF 2.0 site

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
Source materials

References and resources

Everything below is rendered for inspection. Script files are read-only and never run.

References 1

api-reference.md2.7 KB

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 1

agent.py8.7 KB
Display-only source. This catalog never executes bundled scripts.
#!/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()
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