The _expand_arg function in the pam_env module (modules/pam_env/pam_env.c) in Linux-PAM (aka pam) before 1.1.5 does not properly handle when environment variable expansion can overflow, which allows local users to cause a denial of service (CPU consumption).

The pam_env module is vulnerable to a stack overflow (CVE-2011-3148) and a DoS condition (CVE-2011-3149) when parsing users .pam_environment files.

The pam_env module is vulnerable to a stack overflow (CVE-2011-3148) and a DoS condition (CVE-2011-3149) when parsing users .pam_environment files. Additionally a missing return value check inside pam_xauth has been fixed (CVE-2010-3316).

A stack-based buffer overflow flaw was found in the way the pam_env module parsed users' '~/.pam_environment' files. If an application's PAM configuration contained 'user_readenv=1' (this is not the default), a local attacker could use this flaw to crash the application or, possibly, escalate their privileges. (CVE-2011-3148)

A denial of service flaw was found in the way the pam_env module expanded certain environment variables. If an application's PAM configuration contained 'user_readenv=1' (this is not the default), a local attacker could use this flaw to cause the application to enter an infinite loop. (CVE-2011-3149)

The remote Oracle Linux 6 host has packages installed that are affected by multiple vulnerabilities as referenced in the ELSA-2013-0521 advisory.

    - fix environment file handling problems - CVE-2011-3148 (#746619) and       CVE-2011-3148 (#746620)

Tenable has extracted the preceding description block directly from the Oracle Linux security advisory.

Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version number.

Updated pam packages that fix two security issues, several bugs, and add various enhancements are now available for Red Hat Enterprise Linux 6.

The Red Hat Security Response Team has rated this update as having moderate security impact. Common Vulnerability Scoring System (CVSS) base scores, which give detailed severity ratings, are available for each vulnerability from the CVE links in the References section.

Pluggable Authentication Modules (PAM) provide a system whereby administrators can set up authentication policies without having to recompile programs to handle authentication.

A stack-based buffer overflow flaw was found in the way the pam_env module parsed users' '~/.pam_environment' files. If an application's PAM configuration contained 'user_readenv=1' (this is not the default), a local attacker could use this flaw to crash the application or, possibly, escalate their privileges. (CVE-2011-3148)

A denial of service flaw was found in the way the pam_env module expanded certain environment variables. If an application's PAM configuration contained 'user_readenv=1' (this is not the default), a local attacker could use this flaw to cause the application to enter an infinite loop. (CVE-2011-3149)

Red Hat would like to thank Kees Cook of the Google ChromeOS Team for reporting the CVE-2011-3148 and CVE-2011-3149 issues.

These updated pam packages include numerous bug fixes and enhancements. Space precludes documenting all of these changes in this advisory. Users are directed to the Red Hat Enterprise Linux 6.4 Technical Notes, linked to in the References, for information on the most significant of these changes.

All pam users are advised to upgrade to these updated packages, which contain backported patches to correct these issues and add these enhancements.

The remote host is affected by the vulnerability described in GLSA-201206-31 (Linux-PAM: Multiple vulnerabilities)

    Multiple vulnerabilities have been discovered in Linux-PAM. Please       review the CVE identifiers referenced below for details.
  Impact :

    A local attacker could use specially crafted files to cause a buffer       overflow, possibly resulting in privilege escalation or Denial of       Service. Furthermore, a local attacker could execute specially crafted       programs or symlink attacks, possibly resulting in data loss or       disclosure of sensitive information.
  Workaround :

    There is no known workaround at this time.

The pam_env module is vulnerable to a stack overflow (CVE-2011-3148) and a DoS condition (CVE-2011-3149) when parsing users .pam_environment files. Additionally a missing return value check inside pam_xauth has been fixed. (CVE-2010-3316)

Low impact security update from upstream. Only minor and safe changes.

Note that Tenable Network Security has extracted the preceding description block directly from the Fedora security advisory. Tenable has attempted to automatically clean and format it as much as possible without introducing additional issues.

Kees Cook discovered that the PAM pam_env module incorrectly handled certain malformed environment files. A local attacker could use this flaw to cause a denial of service, or possibly gain privileges. The default compiler options for affected releases should reduce the vulnerability to a denial of service. (CVE-2011-3148)

Kees Cook discovered that the PAM pam_env module incorrectly handled variable expansion. A local attacker could use this flaw to cause a denial of service. (CVE-2011-3149)

Stephane Chazelas discovered that the PAM pam_motd module incorrectly cleaned the environment during execution of the motd scripts. In certain environments, a local attacker could use this to execute arbitrary code as root, and gain privileges.

Note that Tenable Network Security has extracted the preceding description block directly from the Ubuntu security advisory. Tenable has attempted to automatically clean and format it as much as possible without introducing additional issues.

Kees Cook of the ChromeOS security team discovered a buffer overflow in pam_env, a PAM module to set environment variables through the PAM stack, which allowed the execution of arbitrary code. An additional issue in argument parsing allows denial of service.

The oldstable distribution (lenny) is not affected.

ID	Name	Product	Family	Severity
75991	openSUSE Security Update : pam (openSUSE-SU-2011:1204-1)	Nessus	SuSE Local Security Checks	medium
75704	openSUSE Security Update : pam (openSUSE-SU-2011:1208-1)	Nessus	SuSE Local Security Checks	medium
69719	Amazon Linux AMI : pam (ALAS-2013-160)	Nessus	Amazon Linux Local Security Checks	medium
68757	Oracle Linux 6 : pam (ELSA-2013-0521)	Nessus	Oracle Linux Local Security Checks	medium
65152	CentOS 6 : pam (CESA-2013:0521)	Nessus	CentOS Local Security Checks	medium
64955	Scientific Linux Security Update : pam on SL6.x i386/x86_64 (20130221)	Nessus	Scientific Linux Local Security Checks	medium
64768	RHEL 6 : pam (RHSA-2013:0521)	Nessus	Red Hat Local Security Checks	medium
59704	GLSA-201206-31 : Linux-PAM: Multiple vulnerabilities	Nessus	Gentoo Local Security Checks	high
57239	SuSE 10 Security Update : pam (ZYPP Patch Number 7814)	Nessus	SuSE Local Security Checks	medium
57126	SuSE 11.1 Security Update : pam (SAT Patch Number 5342)	Nessus	SuSE Local Security Checks	medium
57073	Fedora 15 : pam-1.1.5-1.fc15 (2011-16365)	Nessus	Fedora Local Security Checks	low
57002	Fedora 16 : pam-1.1.5-1.fc16 (2011-16390)	Nessus	Fedora Local Security Checks	low
56701	SuSE 10 Security Update : pam (ZYPP Patch Number 7815)	Nessus	SuSE Local Security Checks	medium
56629	Ubuntu 8.04 LTS / 10.04 LTS / 10.10 / 11.04 / 11.10 : pam vulnerabilities (USN-1237-1)	Nessus	Ubuntu Local Security Checks	medium
56622	Debian DSA-2326-1 : pam - several vulnerabilities	Nessus	Debian Local Security Checks	medium

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