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By Kevin Beaumont
The boilerplate description
"A vulnerability has been identified in Citrix Application Delivery Controller (ADC) formerly known as NetScaler ADC and Citrix Gateway formerly known as NetScaler Gateway that, if exploited, could allow an unauthenticated attacker to perform arbitrary code execution."
What it means in practice
Unauthenticated remote code execution on internet connected Citrix Gateway devices = bad.
Are attackers actually exploiting this vulnerability?
Yes, at scale, against targeted and untargeted assets.
Lame stuff like coin miners, but also devices getting backdoored, and people trying to use this to deploy ransomware inside Windows orgs behind the Citrix boxes.
Vendor advisory and patches
Checking if your device has already been exploited
Check out this tool, which is getting frequent updates: https://github.com/fireeye/ioc-scanner-CVE-2019-19781/tree/v1.2
Scale of the issue
Somewhere in the region of ~100k devices were exploitable with this back in December. After have a huge awareness campaign via all sorts of orgs, this one is about ~10k unpatched devices at present. Those orgs are still in serious danger of exploitation.
If you patched late
You want to run the FireEye tool linked above to look for exploitation, as attackers may have backdoored your device.
I just applied the mitigations
You should also apply the patch, as it hardens the setup - just the mitigations alone present some issues.
By Kevin Beaumont
CVE-2018-13379 is being exploited in the wild on Fortigate SSL VPN firewalls. These exist as a perimeter security control, so it's a bad vulnerability.
Using BinaryEdge.io I can see scanning activity from last night for first time for this vulnerability:
The scanning traffic is taking place across the whole internet it appears, spray and pray style.
The vulnerability is ridiculously easy to exploit, it's a 1996 style pre-auth ../ webserver exploit to read plain text administrator credentials:
May 24th 2019 - Vendor posts advisory - https://fortiguard.com/psirt/FG-IR-18-384
June 4th 2019 - Vendor updates advisory to correct impacted versions
August 9th 2019 - Blog explaining the different vulnerabilities in FortiOS, including this one.
August 14th 2019 - Exploit appears on GitHub and exploitation details posted in TLP Rainbow.
August 17th 2019 - Another exploit, checks if vulnerable before exploit.
August 21nd 2019 - Exploitation seen in wild.
By Tim Corless
Came across this on my travels: https://portswigger.net/daily-swig/webmin-backdoor-blamed-on-software-supply-chain-breach
Webmin software was backdoored for over a year. If you're using one of those vulnerable versions, update now!
According to shodan and some google dorks, there are quite a lot still vulnerable