C99shell is a powerful PHP backdoor that provides a lot of functionality. It can pretty much do everything you want, which results in end-users getting malware onto their systems and/or data getting stolen. The backdoor seems specifically designed to target mobile users. It’s heavily obfuscated as one would expect; after some deobfuscating/decoding we get:It also has a nice web interface:Seems like we are dealing with a slightly updated version of C99Shell, version 2.1:And last but not least, some functionality:”]
Source: https://bartblaze.blogspot.com/2015/03/c99shell-not-dead.html