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Below is the guts of the advisory. Some crude workarounds - changing permission on /sbin/ping, blocking ping packets with a firewall, etc. - would be fairly trivial to implement.

[...]

Affects: All supported versions of FreeBSD.

[...]

II. Problem Description

ping reads raw IP packets from the network to process responses in the pr_pack() function. As part of processing a response ping has to reconstruct the IP header, the ICMP header and if present a "quoted packet," which represents the packet that generated an ICMP error. The quoted packet again has an IP header and an ICMP header.

The pr_pack() copies received IP and ICMP headers into stack buffers for further processing. In so doing, it fails to take into account the possible presence of IP option headers following the IP header in either the response or the quoted packet. When IP options are present, pr_pack() overflows the destination buffer by up to 40 bytes.

III. Impact

The memory safety bugs described above can be triggered by a remote host, causing the ping program to crash. It may be possible for a malicious host to trigger remote code execution in ping.

The ping process runs in a capability mode sandbox on all affected versions of FreeBSD and is thus very constrainted in how it can interact with the rest of the system at the point where the bug can occur.

IV. Workaround

No workaround is available.

[...]



Workaround : rm /usr/bin/ping


If an old server can't be patched, and is gonna stay that way for longer than "oh, I remember that vulnerability being announced a week ago", then

   chmod 4500 /sbin/ping
   mv /sbin/ping /sbin/ping_CVE-2022-23093
   
and put a few-lines shell script in /sbin/ping, which spits out a reminder of the vulnerability, and exits non-zero.




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