A flaw was found in linux-pam. The module pamnamespace may use access user-controlled paths without proper protection, allowing local users to elevate their privileges to root via multiple symlink attacks and race conditions.
The pamenv module in Linux-PAM (aka pam) 1.1.2 and earlier reads the .pamenvironment file in a user's home directory, which might allow local users to run programs with an unintended environment by executing a program that relies on the pamenv PAM check.
Integer signedness error in the pamStrTok function in libpam/pammisc.c in Linux-PAM (aka pam) 1.0.3 and earlier, when a configuration file contains non-ASCII usernames, might allow remote attackers to cause a denial of service, and might allow remote authenticated users to obtain login access with a different user's non-ASCII username, via a login attempt.
Multiple directory traversal vulnerabilities in pamtimestamp.c in the pamtimestamp module for Linux-PAM (aka pam) 1.1.8 allow local users to create arbitrary files or possibly bypass authentication via a .. (dot dot) in the (1) PAMRUSER value to the getruser function or (2) PAMTTY value to the checktty function, which is used by the formattimestampname function.
linux-pam (aka Linux PAM) before 1.6.0 allows attackers to cause a denial of service (blocked login process) via mkfifo because the openat call (for protectdir) lacks ODIRECTORY.
The pamsmclosesession function in pamxauth.c in the pamxauth module in Linux-PAM (aka pam) 1.1.2 and earlier does not properly handle a failure to determine a certain target uid, which might allow local users to delete unintended files by executing a program that relies on the pamxauth PAM check.
The checkacl function in pamxauth.c in the pamxauth module in Linux-PAM (aka pam) 1.1.2 and earlier does not verify that a certain ACL file is a regular file, which might allow local users to cause a denial of service (resource consumption) via a special file.
A vulnerability was found in PAM. The secret information is stored in memory, where the attacker can trigger the victim program to execute by sending characters to its standard input (stdin). As this occurs, the attacker can train the branch predictor to execute an ROP chain speculatively. This flaw could result in leaked passwords, such as those found in /etc/shadow while performing authentications.
It was reported that pamenv and pammail modules do not drop privileges before accessing users' files. This flaw can lead to information disclosure.
Issue was partially addressed in Linux-PAM 1.1.2: http://git.altlinux.org/people/ldv/packages/?p=pam.git;a=commitdiff;h=06f882f30092a39a1db867c9744b2ca8d60e4ad6
The fix in 1.1.2 has some problems though, it fails to switch fsgid/egid and groups (CVE-2010-3430) and does not check setfsuid() return value (CVE-2010-3431): http://thread.gmane.org/gmane.comp.security.oss.general/3311/focus=3551
Fix using newly-introduced pammodutildroppriv / pammodutilregainpriv was committed in upstream CVS and should be included in 1.1.3: http://git.altlinux.org/people/ldv/packages/?p=pam.git;a=commitdiff;h=843807a3a90f52e7538be756616510730a24739a
Acknowledgements:
Red Hat would like to thank Sebastian Krahmer of the SuSE Security Team for reporting this issue.
The pammail and pamenv modules in Linux-PAM before 1.1.2 did not drop privileges before accessing users' files (CVE-2010-3435, see bug #641335). Privilege dropping was added in 1.1.2, but with couple of issues pointed out by Solar Designer:
http://thread.gmane.org/gmane.comp.security.oss.general/3311/focus=3534
The code fails to switch fsgid/egid and groups (CVE-2010-3430) and does not check setfsuid() return value (CVE-2010-3431). Fix using newly-introduced pammodutildroppriv / pammodutilregainpriv was committed in upstream CVS and should be included in 1.1.3: http://git.altlinux.org/people/ldv/packages/?p=pam.git;a=commitdiff;h=843807a3a90f52e7538be756616510730a24739a
An issue dealing with password changes, with respect to the MINDAYS field in /etc/shadow was reported on the Debian BTS (http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=514437) that affects all versions of PAM 1.x. Because of this, if an administrative user sets the password minimum days via chage or passwd, /etc/shadow is updated correctly, but PAM allows the user to change their password with no regard for the MINDAYS setting, effectively allowing them to re-use old passwords immediately and disregard any established password policies that should be enforced.
This is due to the fact that no minimum age password checks are done by PAM in 1.x; in the old versions it was done in unixverifyshadow() by checking the value of of spmin. In newer PAM this check is no longer there.
The pammail and pamenv modules in Linux-PAM before 1.1.2 did not drop privileges before accessing users' files (CVE-2010-3435, see bug #641335). Privilege dropping was added in 1.1.2, but with couple of issues pointed out by Solar Designer:
http://thread.gmane.org/gmane.comp.security.oss.general/3311/focus=3534
The code fails to switch fsgid/egid and groups (CVE-2010-3430) and does not check setfsuid() return value (CVE-2010-3431). Fix using newly-introduced pammodutildroppriv / pammodutilregainpriv was committed in upstream CVS and should be included in 1.1.3: http://git.altlinux.org/people/ldv/packages/?p=pam.git;a=commitdiff;h=843807a3a90f52e7538be756616510730a24739a
The privilege-dropping implementation in the (1) pamenv and (2) pammail modules in Linux-PAM (aka pam) 1.1.2 does not check the return value of the setfsuid system call, which might allow local users to obtain sensitive information by leveraging an unintended uid, as demonstrated by a symlink attack on the .pamenvironment file in a user's home directory. NOTE: this vulnerability exists because of an incomplete fix for CVE-2010-3435.
It was reported that pamenv and pammail modules do not drop privileges before accessing users' files. This flaw can lead to information disclosure.
Issue was partially addressed in Linux-PAM 1.1.2: http://git.altlinux.org/people/ldv/packages/?p=pam.git;a=commitdiff;h=06f882f30092a39a1db867c9744b2ca8d60e4ad6
The fix in 1.1.2 has some problems though, it fails to switch fsgid/egid and groups (CVE-2010-3430) and does not check setfsuid() return value (CVE-2010-3431): http://thread.gmane.org/gmane.comp.security.oss.general/3311/focus=3551
Fix using newly-introduced pammodutildroppriv / pammodutilregainpriv was committed in upstream CVS and should be included in 1.1.3: http://git.altlinux.org/people/ldv/packages/?p=pam.git;a=commitdiff;h=843807a3a90f52e7538be756616510730a24739a
Acknowledgements:
Red Hat would like to thank Sebastian Krahmer of the SuSE Security Team for reporting this issue.