Mobile Users Targeted With SandroRat Posing as Security Software

An attack targeting Google Android users in Europe with a new variant of a remote access tool has taken an ironic twist – the malware at the center of it is posing as a legitimate security program.

According to McAfee researcher Carlos Castillo, an email spam campaign was spotted in Poland distributing a version of the SandroRat with the name ‘Kaspersky_Mobile_Security.apk.

“The email,” he explained in a blog post, “tries to scare a user with the following subject:

“Uwaga! Wykryto szkodliwe oprogramowanie w Twoim telefonie!”
(“Caution! Detected malware on your phone!”)

In the body of the message, the email claims a bank is providing the security software as a means to help customers detect malware targeting mobile transaction numbers (mTAN). Mobile transaction numbers are used to authenticate online banking transactions. Rather than an edition of security software from Kaspersky Lab however, the recipient of the email is actually getting malware. In Germany, the malware is being spread using SMS text messages.

“Spam campaigns (via SMS or email) are becoming a very popular way to distribute Android malware, which can steal personal information or even obtain complete control of a device with tools like SandroRAT,” Castillo noted. “This attack gains credence with the appearance of a bank offering security solutions against banking malware, a typical behavior of legitimate banks.”

SandroRat turned up in hacking community forums last year, and its source code is for sale on the Internet.

Once on the phone, the malware can execute a number of commands, including stealing information such as SMS messages and contact lists and intercepting and recording phone calls.

“A novel functionality of this threat is its ability to access the encrypted Whatsapp chats (available in the path /WhatsApp/Databases/msgstore.db.crypt5 on the SD card) and obtain the unique encryption key using the Google email account of the device to get the chats in plain text and store them in the file waddb.sr,” Castillo noted.

“This decryption routine will not work with Whatsapp chats encrypted by the latest version of the application because the encryption scheme (crypt7) has been updated to make it stronger (using a unique server salt),” he added. “Whatsapp users should update the app to the latest version.”