The pkexec vulnerability, identified as CVE-2021-4034, allows attackers to gain root access on major Linux distributions, including Ubuntu. Patches are currently being developed by both the Linux kernel and pkexec maintainers, as referenced in the kernel mailing list and the polkit GitLab commit. Michael Kerrisk, who raised concerns about this issue back in 2008, has highlighted the urgency of addressing this exploit now that it has been demonstrated in practical scenarios. Users can temporarily mitigate the risk by removing the setuid bit from the pkexec executable.
PREREQUISITESSystem administrators, Linux security professionals, and developers managing Linux environments will benefit from this discussion, particularly those focused on vulnerability management and system hardening.
PeterDonis said:It looks like both the Linux kernel and the pkexec maintainers have patches in the works:
https://lore.kernel.org/lkml/20220126043947.10058-1-ariadne@dereferenced.org/T/
https://lore.kernel.org/lkml/20220126043947.10058-1-ariadne@dereferenced.org/T/ said:Interestingly, Michael Kerrisk opened an issue about this in 2008,
but there was no consensus to support fixing this issue then.
Hopefully now that CVE-2021-4034 shows practical exploitative use
of this bug in a shellcode, we can reconsider.
You can "fix" it at least for the time being by removing the setuid bit from the pkexec executable.jim mcnamara said:WSL Ubuntu shows the problem.