A new bruteforce botnet campaign has infected over 25,000 Windows machines with malware using an unknown infection method, according to Arbor Networks.
Arbor Networks security researcher Matthew Bing reported detecting the password-guessing campaign, codenamed Fort Disco, confirming it has already infected several popular web tools, including Joomla and WordPress.
"We've identified six related command-and-control (C&C) sites that control a botnet of over 25,000 infected Windows machines. To date, over 6,000 Joomla, WordPress, and Datalife Engine installations have been the victims of password-guessing," he wrote.
Bing said the attack has several advanced features that make it next to impossible to fully track. "The malware alone can be picked apart by disassemblers, poked and prodded in a sandbox, but by itself offers no clues into the size, scope, motivation, and impact of the attack campaign. It's much like a historian finding a discarded weapon on an ancient battlefield. Several things can be inferred, but painting a complete picture is difficult," he wrote.
The Arbor Networks researcher said the malware used in the campaign is equally elusive.
"It's unclear exactly how the malware gets installed. We were able to find reference to the malware's original filename (maykl_lyuis_bolshaya_igra_na_ponizhenie.exe) that referred to Michael Lewis' book The Big Short: Inside The Doomsday Machine in Russian with an executable attachment," wrote Bing.
"Another filename, proxycap_crack.exe, refers to a crack for the ProxyCap program. It's unclear if victims were enticed to run these files, and if so, if that is the only means of infection. The command and control sites did not offer additional clues as to the infection mechanism."
Despite the campaign's detection-dodging powers, Bing said the company has had some luck forensically examining the damage it leaves behind once it has finished with its victims. He said the company believes the campaign is linked to six C&C sites and uses at least four malware variants. Each is designed to steal victims' passwords and post them online at a hidden location for collection and use by the criminals.
Bing said the purpose of the password collection currently remains unclear, though it is undoubtedly only the first stage of a larger campaign as the criminals commonly left one of two dormant tools on their victims' systems.
The first was a PHP-based redirector that could be used to direct browsers running Windows with either Internet Explorer, Firefox or Opera to a website linked to a Styx Exploit Kit. The second was a WordPress plugin, which could be used to import posts from a Tumblr blog.
Password theft has been a growing problem within the security community. Numerous groups have been caught targeting professional forums, hoping to steal users' login details. Most recently attacks were detected on the Apple Developer and NASDAQ Community forums.