util-linux umount allows elevated privileges

utillinux-umount-gain-privileges (22241) The risk level is classified as HighHigh Risk

Description:

The util-linux package, included with multiple Linux distributions, could allow a local attacker to gain elevated privileges. A local attacker could use the -r option to remount the file system (if it is busy and unable to unmount completely) and force the unsafe remount, even if the file system is set up as read-only. If 'users' is selected in the fstab entry, an attacker could use this vulnerability to gain root privileges on the system.

*CVSS:

Base Score: 7
  Access Vector: Local
  Access Complexity: Low
  Authentication: Not Required
  Confidentiality Impact: Complete
  Integrity Impact: Complete
  Availability Impact: Complete
 
Temporal Score: 5.2
  Exploitability: Unproven
  Remediation Level: Official-Fix
  Report Confidence: Confirmed

Consequences:

Gain Privileges

Remedy:

Upgrade to the latest version of util-linux (2.12r-pre1 or 2.13-pre3 or later), available from the Linux Kernel Archives FTP site. See References.

As a workaround, ensure the /tc/fstab is edited or delete the setuid bit from the umount.

For Debian GNU/Linux:
Refer to DSA-825-1 and DSA-823-1 for patch, upgrade, or suggested workaround information. See References.

For Red Hat Linux:
Refer to RHSA-2005:782-12 for patch, upgrade, or suggested workaround information. See References.

For Gentoo Linux:
Refer to Gentoo Linux Security Announcement GLSA 2005-09-15 for patch, upgrade, or suggested workaround information. See References.

For Ubuntu Linux:
Refer to USN-184-1 for patch, upgrade, or suggested workaround information. See References.

For other distributions:
Contact your vendor for upgrade or patch information.

References:

  • BugTraq Mailing List, 2005-09-12 20:16:32: util-linux: unintentional grant of privileges by umount.
  • The The Linux Kernel Archives Web site: Index of /pub/linux/utils/util-linux/testing.
  • ASA-2006-014: util-linux and mount security update (RHSA-2005-782)
  • BID-14816: Util-Linux UMount Remounting Filesystem Option Clearing Vulnerability
  • BID-16280: Util-Linux Script Command Arbitrary File Overwrite Vulnerability
  • CVE-2005-2876: umount in util-linux 2.8 to 2.12q, 2.13-pre1, and 2.13-pre2, and other packages such as loop-aes-utils, allows local users with unmount permissions to gain privileges via the -r (remount) option, which causes the file system to be remounted with just the read-only flag, which effectively clears the nosuid, nodev, and other flags.
  • DSA-823: util-linux -- privilege escalation
  • DSA-825: loop-aes-utils -- privilege escalation
  • GLSA-200509-15: util-linux: umount command validation error
  • MDKSA-2005:167: Updated util-linux packages fix umount vulnerability
  • OSVDB ID: 19369: util-linux umount -r Mount Option Removal Restriction Bypass
  • RHSA-2005-782: util-linux and mount security update
  • SA16785: util-linux umount "-r" Re-Mounting Security Issue
  • SA17133: Sun Java Desktop System umount "-r" Re-Mounting Security Issue
  • SA18502: Avaya Products util-linux / mount Security Issue and Vulnerability
  • SUSE-SR:2005:021: SUSE Security Summary Report
  • USN-184-1: umount vulnerability

Platforms Affected:

  • Canonical Ubuntu 4.10
  • Canonical Ubuntu 5.04
  • Debian Debian Linux 3.0
  • Debian Debian Linux 3.1
  • Gentoo Linux
  • Kernel util-linux 2.13-pre1
  • Kernel util-linux 2.13-pre2
  • Kernel util-linux 2.8 to 2.12q
  • MandrakeSoft Mandrake Linux 10.0 AMD64
  • MandrakeSoft Mandrake Linux 10.0
  • MandrakeSoft Mandrake Linux 10.1 X86_64
  • MandrakeSoft Mandrake Linux 10.1
  • MandrakeSoft Mandrake Linux LE2005
  • MandrakeSoft Mandrake Linux LE2005 X86_64
  • MandrakeSoft Mandrake Linux Corporate Server 2.1
  • MandrakeSoft Mandrake Linux Corporate Server 2.1 X86_64
  • MandrakeSoft Mandrake Linux Corporate Server 3.0
  • MandrakeSoft Mandrake Linux Corporate Server 3.0 X86_64
  • MandrakeSoft Mandrake Multi Network Firewall 2.0
  • RedHat Enterprise Linux 2.1 WS
  • RedHat Enterprise Linux 2.1 AS
  • RedHat Enterprise Linux 2.1 ES
  • RedHat Enterprise Linux 3 ES
  • RedHat Enterprise Linux 3 Desktop
  • RedHat Enterprise Linux 3 WS
  • RedHat Enterprise Linux 3 AS
  • RedHat Enterprise Linux 4 WS
  • RedHat Enterprise Linux 4 AS
  • RedHat Enterprise Linux 4 ES
  • RedHat Enterprise Linux 4 Desktop
  • RedHat Linux Advanced Workstation 2.1 Itanium

Reported:

Sep 12, 2005

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