Andrea Lelli previously posted an analysis of a threat dubbed Trojan.Ransomlock. This threat was capable of locking out a user’s desktop and would only relinquish its hold when presented with an unlock code. The code, of course, could only be obtained from a premium rate text number. An infected user would be presented with a screen resembling the following on a compromised machine:
When the blog was posted, Symantec also released a tool that could be used to generate the unlock code. As could be expected, soon after this tool was released the attackers updated their code generation algorithm. In response, Symantec has created an online version of the tool, which handles all known code formats:
Symantec will continuously monitor for any new variants, and update the keygen tool as well.
Note: Thanks to Andrea Lelli for his analysis of the threat and John Park for creating the online version of the unlock tool.