Analysis by: Roland Marco Dela Paz
ALIASES:

Android.Gonfu.C (Symantec); Trojan:AndroidOS/DroidKrungFu.E (Microsoft)

 THREAT SUBTYPE:

Information Stealer, Click Fraud, Malicious Downloader

 PLATFORM:

Android OS

 OVERALL RISK RATING:
 DAMAGE POTENTIAL:
 DISTRIBUTION POTENTIAL:
 REPORTED INFECTION:

  • Threat Type: Trojan

  • Destructiveness: No

  • Encrypted: No

  • In the wild: Yes

  TECHNICAL DETAILS

File Size: 63,222 bytes
File Type: APK
Memory Resident: Yes
Initial Samples Received Date: 31 Mar 2012
Payload: Compromises system security, Connects to URLs/IPs

NOTES:

This backdoor arrives through Trojanized Android apps which require root privilege. Below is a screenshot of an infected app:

It requests permissions outside the intended functionality of the Trojanized app such as the following:

This backdoor installs itself in the /system/lib directory and performs system modifications so that it runs before the Android operating system starts.

It gathers the following information from the affected device:

  • Android version string
  • Brand name of the phone
  • Device ID (IMEI for GSM)
  • Model name of the phone
  • SDK version of the framework

It is capable of executing the following commands:

  • Display Ads
  • Download, install, and execute an .APK file
  • Update itself

It is capable of displaying advertisements on the affected device by downloading a configuration file from the site http://ad.{BLOCKED}droid.com:7500/ad/nadp.php?.It then parses the downloaded configuration which contains details such as ad link, font details, ad text, alignment, ad icon, and others.

This backdoor connects to the following sites to send and receive information:

  • http://amob.{BLOCKED}6.com
  • http://r2.{BLOCKED}o.com/adweb
  • http://ad.{BLOCKED}droid.com:7500
  • http://cast.ra.{BLOCKED}a.com

It may use proxy connections by connecting to the site http://proxy.{BLOCKED}w.cn/api/proxy.

  SOLUTION

Minimum Scan Engine: 9.200
VSAPI OPR PATTERN File: 8.879.00
VSAPI OPR PATTERN Date: 31 Mar 2012

Step 1

Trend Micro Mobile Security Solution

Trend Micro Mobile Security Personal Edition protects Android smartphones and tablets from malicious and Trojanized applications. The App Scanner is free and detects malicious and Trojanized apps as they are downloaded, while SmartSurfing blocks malicious websites using your device's Android browser.

Download and install the Trend Micro Mobile Security App via Google Play.

Step 2

Remove unwanted apps on your Android mobile device

[ Learn More ]

Did this description help? Tell us how we did.