Saturday, July 21, 2007

Ransom-ware Trojan is Back

It seems that ransom-ware trojans are coming back into fashion.

Gpcode-AI (AKA Sinowal-FY) encrypts data on compromised machines before demanding money from users to decrypt it. The malware also include backdoor key-logging features designed to pinch confidential bank account and credit card details from compromised PCs.
"This Trojan belongs to the Synowal family, traditionally used to steal passwords and banking details. This variant, however, not only does that, but blackmails users by encrypting their data so that they cannot access it," explained Luis Corrons, Technical Director of PandaLabs.


When Gpcode-AI installs on the system, it encrypts every single document on the hard disk and creates a file called "read_me.txt" with the kidnapper’s demands (obfuscated copy below). Prospective marks are asked to fork out $300 for a tool to decrypt the files.
Hello, your files are encrypted with RSA-4096 algorithm ( will need at least few years to decrypt these files without our software. All your private information for last 3 months were collected and sent to us.

To decrypt your files you need to buy our software. The price is $300.

To buy our software please contact us at: and provide us your personal code -xxxxxxxxx. After successful purchase we will send your decrypting tool, and your private information will be deleted from our system.

If you will not contact us until 07/15/2007 your private information will be shared and you will lost all your data.

Glamorous team

The demands falsely claim that payment needs to be made by a set deadline or else data will be unrecoverable. In reality the malware lacks any routine to delete encrypted data and the tactic is a simple ruse designed to speed up payment from victims.

The malware uses a complex encryption algorithm to encrypt user files and archives, making it impossible for victims to open files. But the Trojan uses a modified version of RC4 - and not RSA-4096 as mentioned in the text - to scramble data, according to an analysis by anti-virus experts at Kaspersky Labs. The claim that private user files might be sent to a malicious user is also false.

If this happens to you, please don't pay any money. This will only encourage the crime.. if it is profitable then they will do it. Anti Virus developers are currently working on decryption routines for their databases.

As long as you keep regular backups of your essential data then a reformat won't be a problem for you. If you have never considered a backup before now then here is a link to get you started.

Source The Register