fix(sandbox): replace user.uid with user.loginuid in SUID privilege escalation rules#356
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KrakoX wants to merge 1 commit intofalcosecurity:mainfrom
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fix(sandbox): replace user.uid with user.loginuid in SUID privilege escalation rules#356KrakoX wants to merge 1 commit intofalcosecurity:mainfrom
KrakoX wants to merge 1 commit intofalcosecurity:mainfrom
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[APPROVALNOTIFIER] This PR is NOT APPROVED This pull-request has been approved by: KrakoX The full list of commands accepted by this bot can be found here. DetailsNeeds approval from an approver in each of these files:Approvers can indicate their approval by writing |
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…scalation rules sudo and pkexec are SUID root binaries. Falco's user.uid reflects the effective UID, which is always 0 for SUID binaries regardless of who invokes them. The condition user.uid != 0 is therefore always false and the rules never fire. Replace with user.loginuid != 0. The loginuid (kernel audit UID) is set by PAM at session login and preserved through SUID execution. This fires for non-root users on host (loginuid > 0), is silent for root on host (loginuid = 0), and fires for all container processes (loginuid = -1, no PAM session) — covering the primary threat surface. Affects: - Sudo Potential Privilege Escalation (CVE-2021-3156) - Polkit Local Privilege Escalation Vulnerability (CVE-2021-4034) Signed-off-by: KrakoX <krakox.entryway360@passmail.net>
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What type of PR is this?
/kind bug
Any specific area of the project related to this PR?
/area rules
Proposed rule maturity level
/area maturity-sandbox
What this PR does / why we need it:
sudoandpkexecare SUID root binaries. Falco'suser.uidfield reflects the effective UID, which the kernel sets to 0 when any user executes a SUID binary. The conditionuser.uid != 0is therefore permanently false for these binaries.Fix: replace
user.uid != 0withuser.loginuid != 0.user.loginuidis the Linux kernel audit UID (loginuid), set by PAM at session login and preserved through SUID execution. It correctly identifies the actual caller:Verified empirically on Ubuntu 22.04 and 24.04 / kernel 6.8.0 / Falco 0.43.0 via debug rule capturing live
user.uidanduser.loginuidfield values during pkexec and sudo executions.