__________________________________________________________ The U.S. Department of Energy Computer Incident Advisory Capability ___ __ __ _ ___ / | /_\ / \___ __|__ / \ \___ __________________________________________________________ INFORMATION BULLETIN AIX cdmount Vulnerability June 21, 2000 21:00 GMT Number K-052 ______________________________________________________________________________ PROBLEM: The cdmount program allows regular users to mount CD-ROM filesystems. A malicious user could execute cdmount giving commands containing shell metacharacters. PLATFORM: AIX systems with the LPP UMS.objects 2.3.0.0 and below installed. DAMAGE: A malicious user can run arbitrary commands, as root, through shell metacharacter command manipulation. SOLUTION: IBM is currently working on the issue in APAR 4.3x: IY10903 (Authorized Problem Analysis Report). Apply one of the temporary fixes, as suggested by the advisory. ______________________________________________________________________________ VULNERABILITY The risk is MEDIUM. The capability currently exists for root ASSESSMENT: command execution. ______________________________________________________________________________ [****** Begin ISS Advisory ******] --------------------------------------------------------------------------- -----BEGIN PGP SIGNED MESSAGE----- Internet Security Systems Security Advisory June 20, 2000 Insecure call of external program in AIX cdmount Synopsis: The AIX cdmount program allows regular users to mount CD-ROM filesystems. This program is basically a SUID to root wrapper of the mount command. Insecure handling of the arguments to cdmount may allow a local regular user to execute commands as root. Impact: Local users may gain root privileges. Affected Versions: AIX systems with the LPP UMS.objects 2.3.0.0 and below installed. Use the command 'lslpp -l UMS.objects' to verify if a vulnerable version is installed. Description: The cdmount program is part of the AIX UltiMedia Services (UMS) package. UMS provides multimedia applications to AIX workstations. The cdmount program is normally used as a helper to UMS multimedia players. It has SUID root permissions to allow regular users to mount a CD-ROM. The system()library subroutine is used within cdmount to invoke the mount program.. This subroutine spawns a shell to execute the mount command with arguments provided by the user. An attacker may execute arbitrary commands as root by calling cdmount with arguments containing shell metacharacters. Recommendations: ISS recommends removing the SUID bit from cdmount by executing the following command: # chmod 555 /usr/lpp/UMS/bin/cdmount IBM is currently working on the following APAR (Authorized Problem Analysis Report), which will be available soon: APAR 4.3.x: IY10903 Until the official fix is available, if UMS is not being used IBM recommends uninstalling UMS or removing the SUID bit from cdmount. APARs may be ordered using Electronic Fix Distribution (via FixDist) or from the IBM Support Center. For more information on FixDist, go to http://service.software.ibm.com/support/rs6000 or send an email to aixserv@austin.ibm.com with a subject of "FixDist". Additional Information: The Common Vulnerabilities and Exposures (CVE) project has assigned the name CAN-2000-0466 to this issue. This is a candidate for inclusion in the CVE list http://cve.mitre.org, which standardizes names for security problems. Credits: This vulnerability was discovered and researched by Oliver Atoa-Ortiz of the ISS X-Force. ISS would like to thank IBM for their response and handling of this vulnerability. ______ About Internet Security Systems (ISS) Internet Security Systems (ISS) is a leading global provider of security management solutions for the Internet. By providing industry-leading SAFEsuite security software, remote managed security services, and strategic consulting and education offerings, ISS is a trusted security provider to its customers, protecting digital assets and ensuring safe and uninterrupted e-business. ISS' security management solutions protect more than 5,500 customers worldwide including 21 of the 25 largest U.S. commercial banks, 10 of the largest telecommunications companies and over 35 government agencies. 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Revision History June 20, 2000: Initial release. -----BEGIN PGP SIGNATURE----- Version: 2.6.3a Charset: noconv iQCVAwUBOU/eBjRfJiV99eG9AQFmlQQAsLAYTP2T8uk29oSS0WlzhKYDB7W0ZBkz s8466W0VyqPz8RATUJYsISMO8RhDrM2SKaEOkGHcDReQ9yZx7lrbZCVqZu7DaunM xmYxchf3TOzmc2pFhJG5joNTI13iTEzefh+Xv+hHwiU8sL0POppUn4Hvjb3QjYNi oUg5RHGfhpk= =Qx/U -----END PGP SIGNATURE----- [****** End ISS Advisory ******] _______________________________________________________________________________ CIAC wishes to acknowledge the contributions of Internet Security Systems (ISS) for the information contained in this bulletin. _______________________________________________________________________________ CIAC, the Computer Incident Advisory Capability, is the computer security incident response team for the U.S. Department of Energy (DOE) and the emergency backup response team for the National Institutes of Health (NIH). CIAC is located at the Lawrence Livermore National Laboratory in Livermore, California. 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