FreeBSD k5su could allow a local attacker to gain elevated privileges

freebsd-k5su-gain-privileges (9125) The risk level is classified as MediumMedium Risk


The k5su utility in FreeBSD fails to properly verify "wheel" group membership after authentication. This vulnerability could allow a local attacker without "wheel" group membership to obtain superuser privileges.


Gain Privileges


Remove the suid bit from the k5su utility.

— OR —

Upgrade to the latest RELENG security branch, as listed in FreeBSD Security Advisory FreeBSD-SA-02:24.k5su. See References.


  • FreeBSD Security Advisory FreeBSD-SA-02:24.k5su: k5su utility does not honor 'wheel' group.
  • BID-4777: FreeBSD k5su Wheel Group Membership Validation Vulnerability
  • CVE-2002-0755: Kerberos 5 su (k5su) in FreeBSD 4.5 and earlier does not verify that a user is a member of the wheel group before granting superuser privileges, which could allow unauthorized users to execute commands as root.
  • OSVDB ID: 4893: FreeBSD k5su Group Check Failure

Platforms Affected:

  • FreeBSD FreeBSD 4.0
  • FreeBSD FreeBSD 4.4
  • FreeBSD FreeBSD 4.5


May 20, 2002

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