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Vulnerability of Linux kernel: privilege escalation via scm_set_cred

Synthesis of the vulnerability 

An attacker can use a suid/sgid application using SCM, in order to escalate his privileges.
Vulnerable software: Debian, Fedora, Linux, openSUSE, RHEL, SUSE Linux Enterprise Desktop, SLES.
Severity of this announce: 2/4.
Creation date: 29/04/2013.
Références of this computer vulnerability: BID-59538, CERTA-2013-AVI-323, CERTA-2013-AVI-324, CERTA-2013-AVI-375, CVE-2013-1979, DSA-2669-1, FEDORA-2013-6537, FEDORA-2013-6999, MDVSA-2013:176, openSUSE-SU-2013:1971-1, RHSA-2013:0829-01, SUSE-SU-2013:1022-2, SUSE-SU-2013:1022-3, SUSE-SU-2013:1151-1, SUSE-SU-2013:1182-2, SUSE-SU-2014:1316-1, SUSE-SU-2014:1319-1, SUSE-SU-2019:14051-1, VIGILANCE-VUL-12727.

Description of the vulnerability 

A Unix or NetLink socket can use the SCM_CREDENTIALS message, in order to obtain information (pid, uid, gid) of the client process. A service can thus authenticate the connected client.

The scm_set_cred() function of the include/net/scm.h file stores the credentials of the process. However, it uses the effective uid/gid, instead of the read uid/gid. Credentials of suid/sgid applications are thus incorrect, which may help to bypass a security feature.

An attacker can therefore use a suid/sgid application using SCM, in order to escalate his privileges.
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This weakness bulletin impacts software or systems such as Debian, Fedora, Linux, openSUSE, RHEL, SUSE Linux Enterprise Desktop, SLES.

Our Vigil@nce team determined that the severity of this computer weakness is medium.

The trust level is of type confirmed by the editor, with an origin of user shell.

A proof of concept or an attack tool is available, so your teams have to process this alert. An attacker with a specialist ability can exploit this vulnerability announce.

Solutions for this threat 

Linux kernel: version 3.8.11.
The version 3.8.11 is fixed:
  https://www.kernel.org/pub/linux/kernel/v3.0/

Linux kernel: version 3.4.43.
The version 3.4.43 is fixed:
  https://www.kernel.org/pub/linux/kernel/v3.0/

Linux kernel: version 3.0.76.
The version 3.0.76 is fixed:
  https://www.kernel.org/pub/linux/kernel/v3.0/

Linux kernel: patch for scm_set_cred.
A patch is available in information sources.

Debian: new linux packages.
New packages are available:
  linux 3.2.41-2+deb7u1

Fedora 17: new kernel packages.
New packages are available:
  kernel-3.8.11-100.fc17

Fedora 18: new kernel packages.
New packages are available:
  kernel-3.8.8-203.fc18

Mandriva: new kernel packages.
New packages are available:
  kernel-server-3.4.47-1.1.mbs1

openSUSE 12.3: new kernel packages.
New packages are available:
  kernel-3.7.10-1.24.1

RHEL 6 MRG: new kernel-rt packages.
New packages are available:
  MRG Realtime for RHEL 6 Server v.2:
    kernel-rt-3.6.11.2-rt33.39.el6rt

SUSE LE 11: new kernel packages 3.0.80.
New packages are available:
  kernel-3.0.80-0.7.1

SUSE LE 11 SP3: new kernel packages (12/07/2013).
New packages are available. They are all related to the kernel 3.0.82. The main packages are:
  kernel-pae-3.0.82-0.7.9
  kernel-xen-3.0.82-0.7.9
  kernel-ppc64-extra-3.0.82-0.7.9

SUSE LE 11 SP3: new kernel packages (23/10/2014).
New packages are available:
  SUSE LE 11: kernel default-3.0.101-0.40.1
This update also includes some kernel modules packages.

SUSE LE 11 SP4: new kernel packages.
New packages are available:
  SUSE LE 11 SP4: kernel 3.0.101-108.90.1

SUSE LE Real Time 11: new kernel packages.
New packages are available, as indicated in information sources. They are all related to the kernel version 3.0.80.
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