Verifying andmitigating CUPS printing related vulnerabilities from servers

For the past few days a high severity vulnerability impacting multiple GNU/Linux distributions is going around and as expected, this is from the CUPS printing stack.

Details can be found here www.evilsocket.net

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Steps for ensuring your Debian GNU/Linux is not impacted

Check for cups-browsed with: systemctl status cups-browsed

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root@host:~# systemctl status cups-browsed`

cups-browsed.service
  Loaded: not-found (Reason: No such file or directory)
  Active: inactive (dead)

Lets scan the port sudo nmap localhost -p 631 --script cups-info

One scan gave a core dump:

root@host:~# sudo nmap localhost -p 631 --script cups-info

Starting Nmap 7.01 ( https://nmap.org ) at 2024-09-27 11:40 UTC
Stats: 0:00:00 elapsed; 0 hosts completed (0 up), 0 undergoing Script Pre-Scan
nmap: timing.cc:710: bool ScanProgressMeter::printStats(double, const timeval*): Assertion `ltime' failed.
Aborted (core dumped)

But the port itself is closed

Starting Nmap 7.01 ( https://nmap.org ) at 2024-09-27 11:45 UTC
mass_dns: warning: Unable to determine any DNS servers. Reverse DNS is disabled. Try using --system-dns or specify valid servers with --dns-servers
Nmap scan report for localhost (127.0.0.1)
Host is up (0.000054s latency).
PORT    STATE  SERVICE
631/tcp closed ipp

Inspect the installed packages:

apt list --installed | egrep '(cups-browsed|libcupsfilters|libppd|cups-filters|ipp)'

libcupsfilters1/xenial-infra-security,now 1.8.3-2ubuntu3.5+esm1 amd64 [installed,automatic]

Loo for cups related packages: apt list --installed | grep cups

libcups2/xenial-infra-security,now 2.1.3-4ubuntu0.11+esm7 amd64 [installed,automatic]
libcupsfilters1/xenial-infra-security,now 1.8.3-2ubuntu3.5+esm1 amd64 [installed,automatic]
libcupsimage2/xenial-infra-security,now 2.1.3-4ubuntu0.11+esm7 amd64 [installed]

Disable & remove the services:

If the printing and document management is not used on the server, delete the related packages as follows.

apt remove libcups2 libcupsfilters1 libcupsfilters1 libcupsimage2

These steps will make sure that the usually high severity (9.1) rated vulnerabilities are removed from the servers.