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-----BEGIN PGP SIGNED MESSAGE----- =========================================================================== AUSCERT External Security Bulletin Redistribution ESB-2003.0095 -- @stake Security Advisory TruBlueEnvironment Privilege Escalation Attack 15 February 2003 =========================================================================== AusCERT Security Bulletin Summary --------------------------------- Product: TruBlueEnvironment Vendor: @stake, Inc. Operating System: MacOS X 10.2.3 and prior Impact: Root Compromise Access Required: Existing Account Comment: CVE Id: CAN-2003-0088 - --------------------------BEGIN INCLUDED TEXT-------------------- - -----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 @stake, Inc. www.atstake.com Security Advisory Advisory Name: TruBlueEnvironment Privilege Escalation Attack Release Date: 02/14/2003 Application: TruBlueEnvironment Platform: MacOS X (10.2.3 and below) Severity: Local users can gain root privileges Author: Dave G. <email@example.com> Vendor Status: updated version of OS available CVE Candidate: CAN-2003-0088 Reference: www.atstake.com/research/advisories/2003/a021403-1.txt Overview: TruBlueEnvironment is part of the MacOS Classic Emulator. It is setuid root and installed by default. By setting certain environment variables, it is possible to overwrite any file on the system, or create arbitrary files owned as root with the attacker's umask. This vulnerability can be leveraged to create files that will get executed by root through the cron facility. Details: TruBluEnvironment uses an environment variable to determine where to write out debugging information. Local users can set this to environment variable to point at any file on the filesystem. If the file exists, it will be reset to zero bytes. If the file does not exist, it will be created with the umask inherited from the calling process. While attackers cannot create files with execute permissions set, they can create files that are world writable. Under MacOS X, this vulnerability can be used to create files that will be run automatically via cron. By default, cron will launch maintenance scripts using the periodic command. This command will take several files and either 'source' them or run them through a shell interpreter. Since these scripts are running as root, it is possible to obtain administrator privileges on any MacOS X system running cron and TruBlueEnvironment. Vendor Response: Classic: The Mac OS X 10.2.4 release fixes CAN-2003-0088, where an attacker may change an environment variable to create arbitrary files or overwrite existing files, which could lead to obtaining elevated privileges. Credit to Dave G. from @stake, Inc. for discovering this issue. Recommendation: If possible upgrade to Mac OS X 10.2.4. Another solution is to restrict access to the TruBlueEnvironment(*) executable, or remove it entirely if it is not being used. One approach to restrict TruBlueEnvironment executable,and only allow a specific group to execute the application. The following commands will restrict access to the 'admin' group: sudo chown .admin /System/Library/CoreServices/Classic\ Startup.app/Contents/Resources/TruBlueEnvironment sudo chmod 4750 /System/Library/CoreServices/Classic\ Startup.app/Contents/Resources/TruBlueEnvironment (*) Located in /System/Library/CoreServices/Classic Startup.app/Contents/Resources/TruBlueEnvironment Common Vulnerabilities and Exposures (CVE) Information: The Common Vulnerabilities and Exposures (CVE) project has assigned the following names to these issues. These are candidates for inclusion in the CVE list (http://cve.mitre.org), which standardizes names for security problems. CAN-2003-0088 @stake Vulnerability Reporting Policy: http://www.atstake.com/research/policy/ @stake Advisory Archive: http://www.atstake.com/research/advisories/ PGP Key: http://www.atstake.com/research/pgp_key.asc Copyright 2003 @stake, Inc. All rights reserved. - -----BEGIN PGP SIGNATURE----- Version: PGP 8.0 iQA/AwUBPk1bvEe9kNIfAm4yEQIofwCgo2KukjZyxVmEtNwhaairxO3lYP4Anjr2 zEAcY7GhNZn+3evuuqnQsjZp =WZTS - -----END PGP SIGNATURE----- - --------------------------END INCLUDED TEXT-------------------- You have received this e-mail bulletin as a result of your organisation's registration with AusCERT. The mailing list you are subscribed to is maintained within your organisation, so if you do not wish to continue receiving these bulletins you should contact your local IT manager. If you do not know who that is, please send an email to firstname.lastname@example.org and we will forward your request to the appropriate person. This security bulletin is provided as a service to AusCERT's members. As AusCERT did not write the document quoted above, AusCERT has had no control over its content. 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Internet Email: email@example.com Facsimile: (07) 3365 7031 Telephone: (07) 3365 4417 (International: +61 7 3365 4417) AusCERT personnel answer during Queensland business hours which are GMT+10:00 (AEST). On call after hours for member emergencies only. -----BEGIN PGP SIGNATURE----- Version: 2.6.3i Charset: noconv Comment: http://www.auscert.org.au/render.html?it=1967 iQCVAwUBPk5fUSh9+71yA2DNAQHyNAP/c0SPT68v4lIICAPCLJaNQKP6/ofI0YN0 l+k5flMQFkUfMAuqoHQn2JcJtkFD3/8sxNfwmKESM0Bv520DqBFYpLi3QAd5uR8R 1N4PS6AUEs7Hqn2EgUIQwFpjl7SFFsHKOJoHUe6vB7BPqED9RRmF0IRZ0aj8FYMK aEkHAl+rVVU= =kCdp -----END PGP SIGNATURE-----