MobSF

Mobile Security Framework (MobSF) is an automated, open-source cybersecurity tool designed for performing security assessments, penetration testing, and malware analysis of mobile applications. It is an all-in-one platform that enables developers and security professionals to identify vulnerabilities in mobile apps throughout the development lifecycle or during a security audit.

MobSF is distinctive because it integrates multiple testing methodologies into a single interface, handling both static and dynamic analysis without requiring complex manual setup for every scan. It is widely used in DevSecOps pipelines to ensure mobile applications meet security standards before release.

Core Capabilities of MobSF

MobSF provides a comprehensive suite of features that address different layers of mobile application security.

• Static Application Security Testing (SAST): MobSF analyzes the mobile app's source code or binary (e.g., APK or IPA) without executing it. It decompiles the binary to review the underlying code for security flaws. This process identifies issues such as hardcoded API keys, weak cryptographic algorithms, insecure database storage, and misconfigured permissions. It also analyzes manifest files to detect exported components that could be exploited by other apps.

• Dynamic Application Security Testing (DAST): This capability involves analyzing the application while it is running. MobSF can run the app in a controlled environment (an emulator or a real device) to observe its behavior in real time. During dynamic analysis, it monitors network traffic to detect insecure data transmission, checks for sensitive data leakage in logs or memory, and identifies vulnerabilities that only appear during runtime, such as successful bypasses of SSL pinning or root detection.

• Malware Analysis: MobSF scans applications to detect malicious behavior. It checks for known malware signatures, suspicious API calls, and indicators of compromise (IoCs). This is particularly useful for analyzing third-party apps or verifying that an internal app has not been tampered with or infected.

Supported Platforms and File Formats

MobSF supports major mobile and desktop platforms, enabling a unified security testing approach across operating systems.

• Android: Supports analysis of APK (Android Package) and AAB (Android App Bundle) files, as well as zipped source code.

• iOS: Supports analysis of IPA (iOS App Store Package) files and zipped source code. Note that dynamic analysis for iOS typically requires a Mac host.

• Windows: Supports analysis of APPX (Windows App Package) files, which is useful for testing modern Windows applications.

Key Benefits for Cybersecurity Professionals

Automated Security Assessments MobSF drastically reduces the time required for security testing by automating the extraction, decompilation, and analysis phases. A security analyst can upload a file and receive a detailed report in minutes, rather than spending hours manually reverse-engineering the app.

CI/CD Pipeline Integration: The framework is built with REST APIs that enable seamless integration with Continuous Integration/Continuous Deployment (CI/CD) pipelines. This enables "shift-left" security, where every new app build is automatically scanned for vulnerabilities, preventing security debt from accumulating.

Compliance and Reporting: MobSF generates detailed reports that categorize vulnerabilities by severity (High, Medium, Low) and often map them to industry standards such as the OWASP Mobile Top 10. These reports provide actionable remediation advice, making it easier for developers to fix issues and for organizations to prove compliance with security policies.

How MobSF Works

1. Input: The user uploads a mobile application binary (APK, IPA, APPX) or a source code ZIP file to the MobSF web interface or via the API.

2. Decompilation and Scanning: MobSF processes the file, decompiling binaries to recover source code and resources. It then runs pattern-matching rules and security checks against the extracted code.

3. Instrumentation (Dynamic Analysis): For dynamic analysis, MobSF installs the app on a configured emulator or device. It uses instrumentation tools (such as Frida) to hook into the app's processes and monitor its behavior.

4. Reporting: The tool aggregates all findings into a comprehensive report that highlights vulnerability locations, evidence of insecurity, and remediation suggestions.

Frequently Asked Questions

Is MobSF free to use? Yes, MobSF is an open-source tool released under the GNU General Public License v3.0. It is free to download, use, and modify.

Can MobSF analyze iOS apps on Windows? MobSF can perform static analysis of iOS apps (IPA files) on a Windows machine running MobSF (e.g., via Docker). However, dynamic analysis of iOS apps generally requires a MobSF instance running on macOS to interact with the iOS Simulator or hardware.

Does MobSF replace manual penetration testing? No. While MobSF automates the discovery of common vulnerabilities and baseline security flaws, it cannot replace the logic and intuition of a human penetration tester. It is best used as a force multiplier to handle routine checks, allowing human testers to focus on complex logic flaws and business logic vulnerabilities.

ThreatNG enhances the capabilities of the Mobile Security Framework (MobSF) by providing the external, environmental context that static and dynamic app analysis often misses. While MobSF focuses on the internal security of the mobile application binary (APK/IPA) and its code, ThreatNG secures the external infrastructure the application relies on and the broader digital ecosystem in which the app lives.

By combining MobSF's "Inside-Out" analysis of the artifact with ThreatNG's "Outside-In" analysis of the infrastructure, organizations achieve complete mobile security coverage.

External Discovery

MobSF analyzes the files you give it. ThreatNG discovers the files and infrastructure you didn't know existed. ThreatNG automates the discovery of external assets that interact with the mobile application, ensuring MobSF tests the right targets and the backend is secure.

• Discovery of Rogue Mobile Apps: While MobSF analyzes a specific app binary, ThreatNG scans third-party app stores and the open web to find unauthorized or "rogue" versions of that application. It identifies pirated clones or malware-injected versions of the company's app, which can then be fed into MobSF for malware analysis.

• Mapping Backend Infrastructure: Mobile apps are only as secure as the APIs they consume. ThreatNG discovers the external servers, API endpoints, and cloud buckets that the mobile app communicates with. It identifies "Shadow APIs"—backend services used by the mobile app that are undocumented or not managed by the central IT team.

External Assessment

ThreatNG validates the security posture of the endpoints identified by MobSF. When MobSF extracts URLs and IP addresses from the mobile app's source code, ThreatNG performs a rigorous external assessment of those live assets to determine if they are vulnerable to attack.

• Detailed Example (Backend Vulnerability Validation): MobSF analyzes an Android app and identifies a hardcoded string pointing to an API endpoint: https://api.staging.mobile-app.com. ThreatNG takes this URL and performs a comprehensive external assessment. It checks the server's SSL/TLS configuration, looks for open ports (like an exposed database port), and checks for server-side vulnerabilities. If ThreatNG finds that api.staging.mobile-app.com is running a vulnerable version of Nginx, it confirms that the mobile app is communicating with a compromised backend, a critical risk that MobSF alone cannot validate.

• Detailed Example (Cloud Storage Assessment): MobSF detects that an iOS app is configured to upload user photos to an AWS S3 bucket. ThreatNG assesses that specific bucket from the public internet. If ThreatNG determines that the bucket is configured with "Public Read/Write" permissions, it flags a critical data-leak risk. This validates that the app's storage mechanism is insecure, providing the context needed to fix the cloud configuration.

Reporting

ThreatNG unifies the mobile security narrative by merging application-level findings with infrastructure-level risks.

• Unified Mobile Ecosystem Reports: ThreatNG can generate reports that correlate app vulnerabilities with backend risks. A report might highlight: "The mobile app (analyzed by MobSF) uses weak pinning AND connects to a backend server (analyzed by ThreatNG) that supports deprecated TLS 1.0." This provides a holistic view of the attack surface.

• Supply Chain Risk Reporting: ThreatNG reports on the third-party SDKs and external services the app communicates with. It scores the risk of these external dependencies, helping developers decide whether to keep or remove a specific third-party library found by MobSF.

Continuous Monitoring

Mobile apps are updated periodically, but backend infrastructure changes daily. ThreatNG provides the continuous monitoring layer that MobSF (which is typically scan-based) lacks.

• Backend Drift Detection: Even if the mobile app binary hasn't changed, the server it communicates with might have. ThreatNG continuously monitors the API endpoints hardcoded in the app. If a backend server suddenly opens a high-risk port (like SSH) or its SSL certificate expires, ThreatNG detects this "Infrastructure Drift" immediately. It alerts the team that the mobile app is now communicating with an insecure endpoint, prompting an investigation.

• Rogue Asset Alerts: ThreatNG continuously scans for new instances of the brand's mobile app appearing on unauthorized marketplaces. If a new "Modded" version of the app appears on a dark web forum, ThreatNG triggers an alert, allowing the security team to investigate the threat before it spreads to customers.

Investigation Modules

ThreatNG’s investigation modules allow analysts to pivot from a MobSF finding to a deep-dive forensic investigation of the external threat landscape.

• Detailed Example (Domain Intelligence Investigation): MobSF extracts a list of all URLs found in an app's binary. An analyst notices a suspicious domain: analytics-tracker-fast.com. ThreatNG’s Domain Intelligence module investigates this domain. It reveals the domain was registered 2 days ago via an anonymous registrar and is hosted on an IP block associated with known mobile malware command-and-control (C2) servers. This investigation confirms the app has been infected with a malicious SDK or is a trojanized version.

• Detailed Example (Sensitive Code Exposure Investigation): MobSF identifies a hardcoded API key in an app. ThreatNG’s Sensitive Code Exposure module then investigates public repositories (like GitHub) to see if the source code containing that key has also been leaked. If ThreatNG finds the full source code repository publicly available online, it escalates the severity of the finding from "Hardcoded Key" to "Full Source Code Compromise."

Intelligence Repositories

ThreatNG enriches MobSF findings with global threat intelligence to determine if the app is being actively targeted.

• Ransomware Intelligence: ThreatNG checks the backend IP addresses used by the mobile app against its ransomware intelligence feeds. If the app's backend API is hosted on a network subnet currently targeted by a ransomware campaign, ThreatNG flags the infrastructure as "Imminent Risk" and prioritizes patching.

• DarCache Dark Web Intelligence: ThreatNG monitors the dark web for the specific API keys or credentials found by MobSF inside the app. If MobSF finds a "Stripe API Key" in the code, and ThreatNG finds that same key for sale on a dark web marketplace, it confirms that the key has already been scraped and is being actively exploited.

Complementary Solutions

ThreatNG serves as MobSF's external intelligence partner, enabling a closed-loop mobile security workflow.

• Complementary Solution (MobSF): The cooperation is bidirectional. MobSF analyzes the mobile binary to extract a list of domains, URLs, and IP addresses that the app communicates with. This list is fed into ThreatNG as a "Target List." ThreatNG then continuously monitors these endpoints for security issues. Conversely, when ThreatNG discovers a rogue mobile app on the open web, it downloads the binary and feeds it to MobSF for automated malware analysis.

• Complementary Solution (SIEM): ThreatNG pushes alerts from the mobile app backend infrastructure to the SIEM. If ThreatNG detects that the app's API server is under attack or has been exposed, the SIEM correlates this with the app's error logs to see if users are being impacted.

• Complementary Solution (API Security Gateways): ThreatNG informs API Gateways about rogue external connections. If ThreatNG identifies a "Shadow API" the mobile app uses but the gateway does not manage, it flags the gap. The security team can then update the gateway configuration to bring that endpoint under management, ensuring the mobile app traffic is inspected and secured.

Examples of ThreatNG Helping

• Helping Validate Supply Chain Attacks: ThreatNG helps by investigating a third-party ad network discovered by MobSF inside an Android app. MobSF flagged the library as suspicious; ThreatNG investigated the ad network's domain and found that it had recently been re-registered by a known threat actor. This confirmed the supply chain compromise, preventing the malicious ad SDK from being shipped in the final release.

• Helping Secure Backend APIs: ThreatNG helps a fintech company by monitoring the API server used by their mobile banking app. While MobSF confirmed the app code was secure, ThreatNG detected a misconfigured firewall on the production API server that exposed the database port to the internet. The alert allowed the team to close the port, securing the customer data accessed by the app.

• Helping Remove Clone Apps: ThreatNG helps a gaming company by discovering 20 "Free Gem Generator" versions of their mobile game hosted on third-party sites. ThreatNG fed these URLs to the takedown service and the binaries to MobSF. MobSF analysis confirmed they were stealing user credentials, validating the need for immediate legal action.