Detected by ESET as Android/Twitoor, this malware is unique because of its resilience mechanism.
ESET researchers discovered an Android backdoor Trojan controlled 
by tweets. Detected by ESET as Android/Twitoor, it is the first malicious app using Twitter instead of a traditional command-and-control (C&C) server.
After launch, the Trojan hides its presence on the system and checks the defined Twitter account in regular intervals for commands. Based on received commands, it can either download malicious apps or change the C&C Twitter account to another one.
“Using Twitter to control a botnet is an innovative step for an Android platform,” says Lukáš Štefanko, the ESET malware researcher who discovered the malicious app.
According to Štefanko, communication channels based on social networks are hard to discover and impossible to block entirely – while simultaneously being extremely easy for the crooks to re-direct communications to another account.
Twitter was first used to control Windows botnets in 2009. “As for the Android space, this means of hiding has remained untapped until now. In the future, however, we can expect that the bad guys will try to make use of Facebook statuses or deploy LinkedIn and other social networks”, envisages Štefanko.
Android/Twitoor has been active since July 2016. It cannot be found on any official Android app store – according to Štefanko – but probably spreads by SMS or via malicious URLs. It impersonates a porn player app or MMS application but without the functionality. Instead, it has been downloading several versions of mobile banking malware. However, the botnet operators can start distributing other malware at any time, including ransomware, according to Štefanko.
“Twitoor serves as another example of cyber criminals innovating their business. Internet users should keep on securing their activities with good security solutions for both computers and mobile devices,” he concludes.
