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SUSE: 2006-039 Moderate: Pwdutils Privilege Escalation Threat

Thomas Gerisch found that the setuid 'chfn' program contained in the Thomas Gerisch found that the setuid 'chfn' program contained in the pwdutils suite insufficiently checks it's arguments when changing pwdutils suite insufficiently checks it's arguments when changing the GECOS field. This bug leads to a trivially exploitable local privilege escalation that allows users to gain root access. We l [More...]. -----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 ______________________________________________________________________________ SUSE Security Announcement Package: pwdutils, shadow Announcement ID: SUSE-SA:2005:064 Date: Fri, 04 Nov 2005 14:00:00 +0000 Affected Products: SUSE LINUX 10.0 SUSE LINUX 9.3 SUSE LINUX 9.2 SUSE LINUX 9.1 SuSE Linux 9.0 SuSE Linux Desktop 1.0 SuSE Linux Enterprise Server 8 SUSE SLES 9 UnitedLinux 1.0 Vulnerability Type: local privilege escalation Severity (1-10): 7 SUSE Default Package: yes Cross-References: - Content of This Advisory: 1) Security Vulnerability Resolved: pwdutils privilege escalation Problem Description 2) Solution or Work-Around 3) Special Instructions and Notes 4) Package Location and Checksums 5) Pending Vulnerabilities, Solutions, and Work-Arounds: - See SUSE Security Summary Report 6) Authenticity Verification and Additional Information ______________________________________________________________________________ 1) Problem Description and Brief Discussion Thomas Gerisch found that the setuid 'chfn' program contained in the pwdutils suite insufficiently checksit's arguments when changing the GECOS field. This bug leads to a trivially exploitable local privilege escalation that allows users to gain root access. We like to thank Thomas Gerisch for pointing out the problem. 2) Solution or Work-Around Removing the setuid bit from /usr/bin/chfn renders chfn useless but also prevents successful exploitation. Note that this workaround only lasts until the next run of SuSEconfig which will restore the setuid bit if you are on permissions level 'easy' or 'secure'. 3) Special Instructions and Notes None 4) Package Location and Checksums The preferred method for installing security updates is to use the YaST Online Update (YOU) tool. YOU detects which updates are required and automatically performs the necessary steps to verify and install them. Alternatively, download the update packages for your distribution manually and verify their integrity by the methods listed in Section 6 of this announcement. Then install the packages using the command rpm -Fhv to apply the update, replacing with the filename of the downloaded RPM package. x86 Platform: SUSE LINUX 10.0: 385e9ef4f03e67ddb50a6a21d5b9f0e9 SUSE LINUX 9.3: 4705772232599de3a2d9dc83c922ee47 SUSE LINUX 9.2: aae77d1eab9d617be89ab993f9f8a47d SUSE LINUX 9.1: 5e957e0370ac82874979e0c02187517e SuSE Linux 9.0: 8cf127c4d2e74f17cf0ff058f4feaf00 Power PC Platform: SUSE LINUX 10.0: 533274d92b8375bc51b6a3684c1cf506 x86-64 Platform: SUSE LINUX 10.0: cc54040195f24925474d1896c45ccb30 SUSE LINUX 9.3: 785543d9276bd5de611ce0e82bc3c066 SUSE LINUX 9.2: 82b384b4d65189c2af84677d7fc02dba SUSE LINUX 9.1: f5d860c203d8dc5c6b85318229fe68d8 SuSE Linux 9.0: 384136f520ebf09d3be779291da92c8d Sources: SUSE LINUX 10.0: f4b6aedde6cf93e1fe5b47bda874e72a SUSE LINUX 9.3: cb0d28c88ecf013418234ed39ff87e85 SUSE LINUX 9.2: e8854e2433279f4a2650d354a07f3605 SUSE LINUX 9.1: 81453f140a633eeb0b0a841b857e49a5 7f5d161dae57bf1fb64cd39269b5255c SuSE Linux 9.0: 6cc9c84bdea5f04c290c55c942327bb0 d463b528a727655b392230302d998976 Our maintenance customers are notified individually. The packages are offered for installation from the maintenance web: https://www.suse.com:443/ https://www.suse.com:443/ ______________________________________________________________________________ 5) Pending Vulnerabilities, Solutions, and Work-Arounds: - See SUSE Security Summary Report ______________________________________________________________________________ 6) Authenticity Verification and Additional Information - Announcement authenticity verification: SUSE security announcements are published via mailing lists and on Web sites. The authenticity and integrity of a SUSE security announcement is guaranteed by a cryptographic signature in each announcement. All SUSE security announcements are published with a valid signature. To verify the signature of the announcement, save it as text into a file and run the command gpg --verify replacing with the name of the file where you saved the announcement. The output for a valid signature looks like: gpg: Signature made using RSA key ID 3D25D3D9 gpg: Good signature from "SuSE Security Team " where is replaced by the date the document was signed. If the security team's key is not contained in your key ring, you can import it from the first installation CD. To import the key, use the command gpg --import gpg-pubkey-3d25d3d9-36e12d04.asc - Package authenticity verification: SUSE update packages are available on many mirror FTP servers all over the world. While this service isconsidered valuable and important to the free and open source software community, the authenticity and the integrity of a package needs to be verified to ensure that it has not been tampered with. There are two verification methods that can be used independently from each other to prove the authenticity of a downloaded file or RPM package: 1) Using the internal gpg signatures of the rpm package 2) MD5 checksums as provided in this announcement 1) The internal rpm package signatures provide an easy way to verify the authenticity of an RPM package. Use the command rpm -v --checksig to verify the signature of the package, replacing with the filename of the RPM package downloaded. The package is unmodified if it contains a valid signature from This email address is being protected from spambots. You need JavaScript enabled to view it. with the key ID 9C800ACA. This key is automatically imported into the RPM database (on RPMv4-based distributions) and the gpg key ring of 'root' during installation. You can also find it on the first installation CD and at the end of this announcement. 2) If you need an alternative means of verification, use the md5sum command to verify the authenticity of the packages. Execute the command md5sum after you downloaded the file from a SUSE FTP server or its mirrors. Then compare the resulting md5sum with the one that is listed in the SUSE security announcement. Because the announcement containing the checksums is cryptographically signed (by This email address is being protected from spambots. You need JavaScript enabled to view it.), the checksums show proof of the authenticity of the package if the signature of the announcement is valid. Note that the md5 sums published in the SUSE Security Announcements are valid for the respective packages only. Newer versions of these packages cannot be verified. - SUSE runs two security mailing lists to which any interested party may subscribe: This email address is being protected from spambots. You need JavaScript enabled to view it. - General Linux andSUSE security discussion. All SUSE security announcements are sent to this list. To subscribe, send an e-mail to . This email address is being protected from spambots. You need JavaScript enabled to view it. - SUSE's announce-only mailing list. Only SUSE's security announcements are sent to this list. To subscribe, send an e-mail to . For general information or the frequently asked questions (FAQ), send mail to or . ==================================================================== SUSE's security contact is or . The public key is listed below. ==================================================================== . Security vulnerability identified in SUSE Linux software, impacting various editions. Users are advised to apply updates promptly.. SUSE Update, Privilege Escalation, Pwdutils Exploit. . Severity: Important. LinuxSecurity.com Team

Nov 04, 2005 •Important SuSE