Red Hat Bugzilla – Bug 733322
CVE-2011-4120 pam_yubico: Authentication bypass via NULL password
Last modified: 2016-09-19 22:48:05 EDT
Created attachment 519836 [details]
Patch that solves this major security bug
What steps will reproduce the problem?
1. When pressing Ctrl-D when Yubico PAM Module prompts for password.
What is the expected output? What do you see instead?
It just login without asking password
What version of the product are you using? On what operating system?
Linux OS. From version 2.4 to 2.7 as I can see
Please provide any additional information below.
Patch included that solves the problem.
Released version 2.8 that resolves the issue.
This is pretty frightening. I'm happy to report I cannot reproduce it, however. Perhaps someone could include more details about PAM config that reproduces it. If this bug has also be reported upstream, please post a link.
I am going to steal this bug to be Security Response product.
A security flaw was found in the way pam_yubico, a pluggable authentication module for yubikeys, performed user authentication, when 'use_first_pass' PAM configuration options was not used and pam_yubico module was configured as 'sufficient' in the PAM configuration.
A remote attacker could use this flaw to circumvent common authentication process and obtain access to the account in question by providing a NULL value (pressing Ctrl-D keyboard sequence) as the password string.
Relevant upstream patch:
This issue affects the versions of the pam_yubico package, as shipped with Fedora release of 14 and 15. Please schedule an update.
This issue affects the versions of the pam_yubico package, as shipped with Fedora EPEL release 5 and Fedora EPEL release 6. Please schedule an update.
Created pam_yubico tracking bugs for this issue
Affects: fedora-all [bug 751726]
Affects: epel-all [bug 751727]
CVE identifier of CVE-2011-4120 has been assigned to this issue:
yubikey-val-2.10-1.fc16, pam_yubico-2.8-1.fc16, ykclient-2.6-1.fc16 has been pushed to the Fedora 16 stable repository. If problems still persist, please make note of it in this bug report.
The yubikey software packages in EPEL5 is still outdated.
pam_yubico-2.4-1.el5.i386.rpm 24-Feb-2011 17:53 17K RPM Package
pam_yubico-2.4-1.el5.x86_64.rpm 24-Feb-2011 17:53 17K RPM Package
ykclient-2.3-1.el5.i386.rpm 08-Jul-2009 04:02 20K RPM Package
ykclient-2.3-1.el5.x86_64.rpm 08-Jul-2009 04:02 19K RPM Package
I request new packages to be built for EPEL5.