Course 42 - Mobile Malware Analysis Fundamentals | Episode 9: Mastering Basic Static Analysis for Mobile Malware

Mobile Malware Static Analysis — Module ConclusionThis episode serves as a knowledge check and consolidation of the basic static-analysis methodology covered across both iOS and Android. The emphasis is not on learning one particular tool, but on developing a repeatable investigation process.1. iOS Static AnalysisSeveral important tools and artifacts are reinforced.class-dumpUsed primarily to extract and inspect Objective-C class information from compiled iOS binaries.It can help reveal:ClassesMethodsInterfacesApplication structureThis gives the analyst an initial picture of how an application is organized.otoolA versatile Mach-O inspection utility.For example:otool -L application can display the application's linked dynamic libraries.Other otool options can provide additional information about the Mach-O binary, making it an important first-stage reverse-engineering tool.2. Finding the iOS ExecutableThe Info.plist contains important application metadata.One useful investigation task is determining the executable associated with the application.Conceptually:IPA ↓ Payload/ ↓ Application.app/ ↓ Info.plist ↓ CFBundleExecutable ↓ Executable Name The CFBundleExecutable value identifies the main executable associated with the application bundle.3. Android Static AnalysisOn Android, the equivalent early-stage artifact is the AndroidManifest.xml.apktool is commonly used to decode an APK so that its manifest and resources can be examined.For example:apktool d application.apk -o decoded_app The resulting manifest can reveal:ActivitiesServicesBroadcast receiversContent providersPermissionsIntent filters4. Intent FiltersA particularly important Android concept is the intent-filter.Intent filters describe the types of intents that an Android component can respond to.For example, a receiver may declare an intent associated with a particular system event.This makes intent filters useful during malware analysis because they help answer:What events is this application designed to react to?For example:Intent ↓ Matching Intent Filter ↓ Android Component ↓ Application Logic This is especially important when investigating applications that react automatically to events such as incoming messages, boot events, connectivity changes, or other system broadcasts.5. The Structured Malware-Analysis MethodologyOne of the most important lessons from the entire module is that malware analysis should follow a structured methodology rather than randomly examining files and tools.A strong workflow is:1. Define the objective ↓ 2. Preserve the sample ↓ 3. Calculate hashes ↓ 4. Search online intelligence resources ↓ 5. Identify platform and file type ↓ 6. Examine metadata ↓ 7. Analyze permissions / capabilities ↓ 8. Inspect code and binaries ↓ 9. Identify suspicious artifacts ↓ 10. Build a behavioral hypothesis ↓ 11. Validate through deeper analysis Why define the objective first?Without a specific objective, malware analysis can become extremely inefficient.For example, different questions require different investigations:What does this application do?Does it communicate with a C2 server?Does it steal SMS messages?What persistence mechanism does it use?What information does it collect?The objective determines which artifacts deserve priority.6. Hashing as an Early Triage TechniqueHashing provides a convenient way to identify a malware sample.Common hashes include:md5sum sample.apk sha256sum sample.apk The hash can then be searched in authorized threat-intelligence databases.This can potentially reveal:Previous detectionsMalware family classificationsExisting researchKnown indicatorsPrevious...