Full Report
Taking inspiration from Vlad’s post I’ve been playing around with alternate means of viewing traffic/data generated by Android apps. The technique that has given me most joy is memory analysis. Each application on android is run in the Dalvik VM and is allocated it’s own heap space. Android being android, free and open, numerous ways of dumping the contents of the application heap exist. There’s even a method for it in the android.os.Debug library: android.os.Debug.dumpHprofData(String filename). You can also cause a heap dump by issuing the kill command:
Analysis Summary
# Tool/Technique: Android Application Heap Dump Analysis (via DDMS/hprof)
## Overview
This technique involves analyzing the memory heap dumps (specifically in HPROF format) of Android applications running in the Dalvik Virtual Machine (VM). The primary purpose is to extract sensitive data—such as credentials, session tokens, and financial information—that exists in cleartext within the application's allocated memory space, bypassing network interception or SSL decryption.
## Technical Details
- Type: Technique
- Platform: Android
- Capabilities: Extracting the memory heap content of a running Android application, viewing in-memory variables, and parsing the resulting HPROF file using standard Java memory viewers or command-line tools (`strings`, `grep`).
- First Seen: The article references an inspiration post and an existing technique, but the date associated with this specific write-up is **February 11, 2013**.
## MITRE ATT&CK Mapping
Since this focuses on extracting data that an application already possesses, it aligns best with data access and credential theft tactics:
- **TA0006 - Credential Access** (If targeting authentication secrets)
- T1003 - OS Credential Dumping (Conceptual overlap, as it's dumping application memory instead of OS/LSASS memory)
- T1003.001 - LSASS Memory (Not directly applicable, but shows the intent of dumping secrets)
- **TA0009 - Collection**
- T1530 - Data from Local System (Focusing on data exfiltrated from collected application memory)
## Functionality
### Core Capabilities
- **Heap Dumping:** Generating an application heap dump (`.hprof` file) using native Android methods like `android.os.Debug.dumpHprofData(String filename)` or by sending signal 10 (`kill -10`).
- **Leveraging DDMS:** Utilizing the Dalvik Debug Monitor Server (DDMS) within Eclipse to initiate the heap dump and configure it to output the standard Java HPROF format (which requires using `hprof-conv`).
- **Data Extraction:** Using command-line tools like `strings` and `grep` on the resulting HPROF file to locate plaintext data, including usernames, passwords, credit card details, and JSON responses.
### Advanced Features
- **Bypassing Network Controls:** This technique is explicitly described as an alternative for applications employing strong network security controls, such as **certificate pinning**, where MITM proxying (like Burp or Mallory) fails. By reading memory, the analyst captures data immediately before it is encrypted for transmission or immediately after it is decrypted upon receipt.
- **Forensic Analysis:** Determining the application's internal workings and data handling processes by examining memory contents.
## Indicators of Compromise
Since this describes a *method* rather than a specific piece of deployed malware, IoCs are centered around the artifacts generated by the technique:
- File Hashes: N/A (Tool-driven analysis)
- File Names: Application-specific `.hprof` dump files (e.g., `/tmp/android43208542802109.hprof`).
- Registry Keys: N/A
- Network Indicators: N/A (The technique avoids network interception).
- Behavioral Indicators: Execution of `kill -10` against a target Android process; usage of developer tools like DDMS to trigger memory snapshots.
## Associated Threat Actors
The article positions this as a technique used by security researchers and penetration testers. Specific threat actor groups are not mentioned in association with this memory analysis method, although this technique is universally applicable for mobile security assessments and malware analysis.
## Detection Methods
Detection focuses on monitoring the execution of the dumping mechanism on a device:
- Signature-based detection: Difficult for generic memory analysis unless specific memory analysis tools are flagged.
- Behavioral detection: Monitoring for system calls or signals related to process memory manipulation (`kill -10`) or the systematic use of developer tools (DDMS) outside of standard development environments.
- YARA rules: Not directly applicable to the analysis method itself, but could be written to detect embedded plaintext secrets found *after* the dump is created.
## Mitigation Strategies
This technique highlights weaknesses in how certain application data is managed in memory:
- Prevention measures: Implementing proper memory cleanup routines to *zero out* or overwrite sensitive variables (passwords, tokens) immediately after they are used, rather than relying on garbage collection.
- Hardening recommendations: Employing techniques like **memory encryption** or obfuscating sensitive data structures within the mobile application. Restricting debugging services access on production builds.
## Related Tools/Techniques
- **DDMS (Dalvik Debug Monitor Server):** The primary tool mentioned for facilitating the heap dump.
- **HPROF Converter (`hprof-conv`):** Used to convert the Android-specific HPROF format to the standardized Java format.
- **Memory Analysis Tools:** Other Java memory viewers used to parse the converted `.hprof` files.
- **Proxy Tools (Mallory/Burp):** Memory analysis is suggested as an alternative when these tools fail due to certificate pinning.