Library File In Some Android Apps Calls Home to C&C Server

Weichao Sun, a Trend Micro mobile threat researcher, has discovered a malicious library file within certain Android applications, which hides its routines within the dynamic library in order to make detection harder and avoid removal.

The malicious library, libvadgo, was developed using a common Android development toolset. Once libvadgo is called via Java_com_airpuh_ad_UpdateCheck_DataInit, the phone is scanned for signs of being rooted. If so, then various commands are initiated and a separate file is run.

“As mentioned previously, what makes this threat noteworthy is [the] use of the dynamic library libvadgo.so. This type of malware hides its malicious routines in the said dynamic library, making it hard to analyze,” Sun explained.

“It also kills certain processes, hooks important system commands, and replaces files to make detection and removal solutions difficult. If more Android malware use this technique in the future, delivering analysis and solutions will prove to be challenging…” The malicious library runs specifically on rooted devices, and is likely spread through third-party sources. Additional research, including detection methods, can be viewed here.

Sun did not mention specific application names that housed the malicious code in his report, but did tell SecurityWeek that all came from a third-party app store and included types such as Joke box app, CPU overclock tool, Push Ups Windows custom tool, Timer clock, Memory management. Call recorder, App cache cleaner, and Super User