Kerberos 5 (k5su) utility allows an attacker to gain elevated privileges

kerberos5-k5su-elevate-privileges (7956) The risk level is classified as HighHigh Risk

Description:

The (k5su) utility in Kerberos 5 could allow a local attacker to gain elevated privileges. The (k5su) utility uses the getlogin() system call to determine if the current user is (root). If a process is started with root privileges, a local attacker using the (k5su) utility can gain root privileges on the system.


Consequences:

Gain Access

Remedy:

For FreeBSD 4.4-STABLE:
Upgrade to the latest version of FreeBSD (4.4-STABLE dated 2002-01-15 or later), as listed in FreeBSD, Inc. Security Advisory FreeBSD-SA-02:07. See References.

For FreeBSD 4.4-RELEASE:
Upgrade to the latest version of FreeBSD (4.4-RELEASE dated 2002-01-17 or later), as listed in FreeBSD, Inc. Security Advisory FreeBSD-SA-02:07. See References.

— OR —

Apply the k5su patch, as listed in FreeBSD, Inc. Security Advisory FreeBSD-SA-02:07. See References.

References:

  • FreeBSD Security Advisory FreeBSD-SA-02:07: Kerberos 5 su command uses getlogin for authorization.
  • BID-3919: Kerberos 5 su Privilege Escalation Vulnerability
  • CVE-2002-0754: Kerberos 5 su (k5su) in FreeBSD 4.4 and earlier relies on the getlogin system call to determine if the user running k5su is root, which could allow a root-initiated process to regain its privileges after it has dropped them.
  • OSVDB ID: 4892: Kerberos 5 on FreeBSD k5su getlogin Local Privilege Escalation

Platforms Affected:

  • FreeBSD FreeBSD 4.4
  • FreeBSD FreeBSD Ports Collection
  • MIT Kerberos 5

Reported:

Jan 18, 2002

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