We’re dung for! Hackers hit firms with ransomware by exploiting Shitrix flaw

Graham Cluley

We're dung for! Hackers hit firms with ransomware by exploiting Shitrix flaw

We're dung for! Hackers hit firms with ransomware by exploiting Shitrix flaw

About two weeks ago alarm bells rang over a newly-discovered (and unpatched) flaw in Citrix servers. The vulnerability, technically dubbed CVE-2019-19781 but also known as “Shitrix”, was found to be present on Citrix Application Delivery Controller and Citrix Gateway servers (formerly known as Netscaler ADC and Netscaler Gateway respectively) commonly used on corporate networks.

Then we discovered hackers were seemingly-altruistically inoculating vulnerable servers from further Shitrix attacks, but actually at the same time opening a secret backdoor to allow future cybercriminal campaigns.

Things really took a bizarre twist when the Dutch press reported the threat of more traffic jams as government employees in The Netherlands were forced by the vulnerability to travel to work rather than log in remotely.

And now? Now, with sad predictability, we’re getting the first reports of ransomware being planted by hackers exploiting the Shitrix flaw.

Specifically, researchers are reporting evidence that they have seen the REvil (also known as Sodinokibi) ransomware being planted by attackers. That’s the same ransomware which at the end of December hit Travelex so hard that they’re still trying to recover.

At the time of writing Citrix hasn’t finished issuing security patches for all of its vulnerable products (some are out, but others aren’t quite yet), but there really is no reason why businesses shouldn’t be considering as a matter of priority applying the various anti-Shitrix mitigation steps.

You may also want to consider trying out the free tool that Citrix has developed with FireEye to detect Indicators of Compromise based on based on known Shitrix attacks and exploits.

The tool can’t give you a clean bill of health, but it can warn you if it detects anything suspicious that it knows about.

It should go without saying that any businesses running vulnerable Citrix servers should not only follow these steps, but also apply security patches as soon as they are available.

Graham Cluley Graham Cluley is a veteran of the anti-virus industry having worked for a number of security companies since the early 1990s when he wrote the first ever version of Dr Solomon's Anti-Virus Toolkit for Windows. Now an independent security analyst, he regularly makes media appearances and is an international public speaker on the topic of computer security, hackers, and online privacy. Follow him on Twitter at @gcluley, or drop him an email.