RHSA-2010:0891: Moderate: pam security update

First published: Tue Nov 16 2010(Updated: )

Pluggable Authentication Modules (PAM) provide a system whereby<br>administrators can set up authentication policies without having to<br>recompile programs that handle authentication.<br>It was discovered that the pam_namespace module executed the external<br>script namespace.init with an unchanged environment inherited from an<br>application calling PAM. In cases where such an environment was untrusted<br>(for example, when pam_namespace was configured for setuid applications<br>such as su or sudo), a local, unprivileged user could possibly use this<br>flaw to escalate their privileges. (CVE-2010-3853)<br>It was discovered that the pam_env and pam_mail modules used root<br>privileges while accessing user's files. A local, unprivileged user could<br>use this flaw to obtain information, from the lines that have the KEY=VALUE<br>format expected by pam_env, from an arbitrary file. Also, in certain<br>configurations, a local, unprivileged user using a service for which the<br>pam_mail module was configured for, could use this flaw to obtain limited<br>information about files or directories that they do not have access to.<br>(CVE-2010-3435)<br>Note: As part of the fix for CVE-2010-3435, this update changes the default<br>value of pam_env's configuration option user_readenv to 0, causing the<br>module to not read user's ~/.pam_environment configuration file by default,<br>as reading it may introduce unexpected changes to the environment of the<br>service using PAM, or PAM modules consulted after pam_env.<br>It was discovered that the pam_xauth module did not verify the return<br>values of the setuid() and setgid() system calls. A local, unprivileged<br>user could use this flaw to execute the xauth command with root privileges<br>and make it read an arbitrary input file. (CVE-2010-3316)<br>Red Hat would like to thank Sebastian Krahmer of the SuSE Security Team for<br>reporting the CVE-2010-3435 issue.<br>All pam users should upgrade to these updated packages, which contain<br>backported patches to correct these issues.<br>

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