FinSpy for Android tools - 2020

This repository contains the tools we developed while investigating on a new FinSpy implant for Android as explained in the AmnestyTech report and our analysis report.

These tools are meant to:

• extract and decode obfuscated strings;
• extract and parse configuration whether it is stored into the APK or into the DEX.

FinSpy variants detection

We provide Yara rules (located at python/yara) detecting 4 variations of FinSpy for Android:

• FinSpy_ConfigInAPK: FinSpy configuration stored into the APK
• FinSpy_DexDen: FinSpy configuration stored into the DEX
• FinSpy_TippyTime: use of a timestamp to generate local socket address
• FinSpy_TippyPad: use of basic pad to obfuscate strings

Tools overview

• java_parser.py extracts FinSpy_TippyPad obfuscated strings from Java source code
• string_decoder.py decodes obfuscated strings
• analyze_samples.py detects, extracts and parses FinSpy configuration of all samples stored in a given directory

NB: analyze_samples.py extracts and parses configuration whether it is stored into the APK or into the DEX.

Installation

• clone this repository: git clone https://github.com/DefensiveLabAgency/FinSpy-for-Android.git
• enter into the cloned directory: cd FinSpy-for-Android.git
• create a Python 3 virtual env.: virtualenv -p python3 venv
• activate the venv: source venv/bin/activate
• then: cd python
• install dependencies: pip install -r requirements.txt
• play!

Configuration parsing

The scripts we provide parse what we were able to reverse so few configuration fields are not parsed. Anyway, if you run python analyze_samples.py ../samples yara/FinSpy.yar output, the script will generate the following directory structure:

• output/
  • summary.txt an analysis summary report
  • <sample name>/
    • config.dat raw extracted configuration
    • config.hex hexdump of the extracted configuration
    • config.json JSON representation of the parsed configuration
    • config.txt text representation of the parsed configuration

Examples

Example of summary:

../samples/WIFI.apk
Matching Yara rules: [FinSpy_DexDen, FinSpy_TippyTime, FinSpy_TippyPad]
FinSpy configuration: found and extracted

../samples/9c8bf89d043ba3ed802d6d4f9b290747d12822402d61065adfbcb48a740a47b8.apk
Matching Yara rules: [FinSpy_DexDen, FinSpy_TippyTime, FinSpy_TippyPad]
FinSpy configuration: found and extracted

Example of parsed configuration:

[...]
[8402800][803770] TlvTypeConfigTargetProxy = 185.[redacted]
[8402800][803770] TlvTypeConfigTargetProxy = 103.[redacted]
[8403008][803840] TlvTypeConfigTargetPort = 443
[8676208][846370] TlvTypeConfigSMSPhoneNumber = +04[redacted]
[8676976][846670] TlvTypeMobileTrojanID = 12[redacted]
[8676672][846540] TlvTypeMobileTrojanUID = 22[redacted]
[16654656][fe2140] TlvTypeUserID = 1000
[8392000][800d40] TlvTypeTrojanMaxInfections = 9
[8677440][846840] TlvTypeConfigMobileAutoRemovalDateTime = 0
[8403776][803b40] TlvTypeConfigAutoRemovalIfNoProxy = 168
[8675472][846090] TlvTypeMobileTargetHeartbeatEvents = 
 - SIM changed: True
 - Cell location changed: False
 - Network changed: True
 - Call: False
 - Wifi connected: True
 - Data link available: True
 - Network activated: False
 - Data available: True
[8681872][847990] TlvTypeInstalledModules = 
 - Spy calls: False
 - Intercept calls: False
 - SMS: True
 - Address book: True
 - Logging: False
 - Location: True
 - Call log: True
 - Calendar: True
 - Spy chats: True
[...]

Credits

• Esther Onfroy
• Etienne Maynier