Hackers are scanning to find Citrix servers vulnerable to a critical security flaw in ADC and Gateway products, researchers warned.
Published in December, the serious vulnerability, referred to as CVE-2019-19781, affects the Citrix Application Delivery Controller (ADC) - also known as the NetScaler ADC - along with the Citrix Gateway, formerly known as the NetScaler Gateway. Initially reported by Mikhail Klyuchnikov of Positive Technologies, critical vulnerabilities allow directory switching and, if exploited, allow threat carriers to conduct remote code (RCE) attacks.
According to Citrix's security advisory, these products are affected:
- Citrix ADC and Citrix Gateway version 13.0 all supported builds
- Citrix ADC and NetScaler Gateway version 12.1 all supported builds
- Citrix ADC and NetScaler Gateway version 12.0 all supported builds
- Citrix ADC and NetScaler Gateway version 11.1 all supported builds
- Citrix NetScaler ADC and NetScaler Gateway version 10.5 all supported builds
Researchers estimate that at least 80.000 organizations in 158 countries are users of ADC and could therefore run risk. Risk line companies are mainly based on USA About 38% - as well as in the United Kingdom, Germany, the Netherlands and Australia.
"Depending on the specific parameters, Citrix applications can be used to connect to workstations and critical businesses. systems (including ERP), ”says Positive Technologies. "In almost all cases, Citrix applications are accessible on the perimeter of the company's network and are therefore the first to be attacked. This vulnerability allows any unauthorized intruder not only to have access to published applications, but also to attack other resources of the Citrix server internal network. ”
According to Bleeping Computer, cybersecurity researchers have identified a spike in scans for Citrix servers that are potentially vulnerable to error.
A public exploitation code does not seem to be widely used - at least not yet. The Dean of Research, Johannes Ullrich of the SANS Institute of Technology, noted in his controls that the current scans do not appear to be "complex" in any way - some of which do not go beyond GET requests - but added that "other sources I consider credible have stated that they were able to generate code execution exploitation. ”
An update code has not yet released the issue, but Citrix has in the meantime published guidelines for handling the situation. The company recommends that IT admins execute a set of commands accessible here, to tailor response policies.
"Citrix strongly urges customers to implement the measure immediately. Customers will then need to upgrade all their vulnerable devices to a stable version firmware of the device when it is released ", he says.