Internet ne'er-do-wells have put together a strain of Android malware that spreads like a email worm rather than acting like a conventional trojan.
Selfmite spreads by automatically sending a text message to contacts in the infected phone’s address book. Theses SMS messages contain a URL that redirects to the malware: ‘Dear [NAME], Look the Self-time, http://goo.gl/[REDACTED]'.
If a user clicks on the goo.gl shortened link, they are invited to download and install an APK file which appears as an icon on their smartphone menu after installation.
Once launched, Selfmite reads the device’s address book before sending the message to 20 different contacts using their name as a greeting, restarting the infection cycle. After sending the malicious SMS messages to fresh marks, the initial victim is invited to download and install Mobogenie, a legitimate app for managing and installing Android apps.
Affiliates get a pay-per-install fee for distributing Mobogenie and using unscrupulous tactics to ramp up this income seems to have motivated the attack.
Mobile security firm AdaptiveMobile, which has begun blocking the spread of messages containing links to the worm, has found infected devices on mobile networks in North America. The worm was first discovered in the US, where it seems concentrated, but activity has also been recorded from a dozen other countries worldwide, according to AdaptiveMobile.
Android Trojans that pose as games or useful utilities are commonplace, especially on third-party app stores. These malicious apps typically offer access to premium games for little or no charge, a potential give-away to more clued-up users. Selfmite comes in a message "sent" by someone known to a potential victim, a different tactic that's perhaps more likely to be believed.
“SMS worms for Android smartphones have previously been rare, but this and the recent Samsapo worm in Russia may indicate that cybercriminals are now starting to broaden their attacks on mobile phones to use different techniques that users may not be aware of,” Denis Maslennikov, a security analyst at AdaptiveMobile explained.
To redirect users to the Mobogenie app, the Selfmite worm uses an advertising platform.
"We believe that an unknown registered user of the advertising platform abused a legal service and attempted to increase the number of Mobogenie app installations using malicious software," Maslennikov added.
In addition to boosting affected users' bills, by automatically sending SMS spam messages, the worm puts the infected device in danger of being blocked by the mobile operator. AdaptiveMobile has contacted Google and the malicious URL has already been disabled.
AdaptiveMobile's write-up of the threat - featuring screenshots and code samples - can be found here.
Separately, mobile security firm Lookout has discovered a strain of Android malware in Google Play, dubbed BankMirage.
BankMirage is a fake banking app that clones the original app from an Israeli bank while adding a layer of code which steals victims' usernames, according to Lookout's blog post about the malware.
Curiously, the app steals users’ credentials but not their passwords. Once this information has been stolen, the fake app prompts the victim to reinstall the legitimate banking app from the Play store. ®