Graham Cluley writes:
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.
Read more on GrahamCluley.com.