A hacking group called d33ds broke into the online shop of a rival hacker who sells unauthorized access to high-profile websites and data.

This illegal marketplace has been used in the past to advertise information stolen from websites belonging to the U.S. Army, the U.S. Department of Defense, the South Carolina National Guard and other institutions. Its owner, a hacker calling himself Srblche, also offered services that included compromising the particular servers his customers wanted.

According to Rob Rachwald, director of security strategy at security firm Imperva, Srblche is believed to be Kuwaiti. "We tracked his Facebook profile," Rachwald said Thursday.

Members of the hacking community accused Srblche in the past of stealing other people's tools from underground forums and trying to profit from them, which might explain why d33ds targeted him.

"Anyone willing to pay for this service must be as stupid as he is," d33ds wrote in its announcement of Srblche's online catalogue being hacked. The group published information about the server, the password hashes of his customers and even the hacker's administrative access code in plain text.

It's not sure how the compromise occurred, but Imperva's researchers believe that the group might have broken in through some other application hosted on the same server.

"D33ds is the same group that hacked RankMyHack.com. [...] This is how Rankmyhack was breached," they said in a blog post. RankMyHack is a website that awards points for Web compromises depending on how big or important the target was. Hackers compete for a higher position on the leaderboard.

Imperva is not aware of any case where stolen information sold by Srblche was actually used in an attack against an organization. However, it would be hard to determine if this happened because attackers don't publicly boast about it, said Rachwald.

When a hacker gets hacked, there is a high chance of sensitive data stolen from companies being made public.

To avoid putting themselves in such a situation, organizations should take several precautions. They should regularly use Google to search for hints of vulnerabilities on their websites because this is a common practice used by hackers. They should also test their websites with a vulnerability scanner and install a web application firewall, Rachwald said.