When the source code to a suspected Russian-made malware leaked online in 2013, guess who used it? A new release from WikiLeaks claims the U.S. CIA borrowed some of the code to bolster its own hacking operations.
On Friday, WikiLeaks released 27 documents that allegedly detail how the CIA customized its malware for Windows systems.
The CIA borrowed a few elements from the Carberp financial malware when developing its own hacking tool known as Grasshopper, according to those documents.
Carberp gained infamy as a Trojan program that can steal online banking credentials and other financial information from its victims' computers. The malware, which likely came from the criminal underground, was particularly problematic in Russia and other former Soviet states.
In 2013, the source code was leaked, sparking worries in the security community that more cybercriminals might use the malware.
Friday's WikiLeaks release includes supposed CIA user manuals that show the agency took an interest in the malware, especially with the way it can survive and linger on a Windows PC.
"The persistence method, and parts of the installer, were taken and modified to fit our needs," the U.S. spy agency allegedly wrote in one manual, dated January 2014.
It’s unclear why the agency chose Carberp. However, the borrowed elements were only used in one "persistence module" meant for the CIA's Grasshopper hacking tool. That tool is designed to build custom malware configured with different payloads, according to a separate document.
The WikiLeaks' release describes several other modules that work with Grasshopper to let malware persist on a PC, such as by leveraging Windows Task Scheduler or a Windows registry run key.
However, no actual source code was included in Friday's release. Nevertheless, the documents will probably help people detect the CIA's hacking tools -- which is WikiLeaks' intention in releasing the classified information.
Last month, WikiLeaks began releasing a trove of secret files allegedly obtained from the CIA. Those first leaks described how the agency has a library of hacking techniques borrowed from malware out in the wild.
The U.S. spy agency has so far declined to comment on the authenticity of WikiLeaks' document dump.