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-----BEGIN PGP SIGNED MESSAGE----- =========================================================================== AUSCERT External Security Bulletin Redistribution ESB-2003.0540 -- OpenBSD Security Advisory off-by-one error in realpath(3) 05 August 2003 =========================================================================== AusCERT Security Bulletin Summary --------------------------------- Product: libc function: realpath(3) Publisher: OpenBSD Operating System: OpenBSD 3.3 and prior BSD Linux Impact: Denial of Service Execute Arbitrary Code/Commands Increased Privileges Ref: AL-2003.13 ESB-2003.0535 - --------------------------BEGIN INCLUDED TEXT-------------------- An off-by-one error exists in the C library function realpath(3). This is the same bug that was recently found in the wu-ftpd ftpd server by Janusz Niewiadomski and Janusz Niewiadomski. The OpenBSD ftp daemon does not use realpath(3) in a way that could be exploited, however a number of other system binaries also use the function. It is not currently known whether or not this bug results in an exploitable security hole on OpenBSD. Since the bug led to an exploitable hole in wu-ftpd, it is entirely possible that some program using realpath(3) under OpenBSD may be vulnerable to attack. For OpenBSD 3.3 and higher, the ProPolice stack protector should provide some protection from this bug, but this cannot be guaranteed. This bug has been fixed in OpenBSD-current as well as the 3.2 and 3.3 stable branches. Patches are available for OpenBSD 3.2 and 3.3. Patch for OpenBSD 3.2: ftp://ftp.OpenBSD.org/pub/OpenBSD/patches/3.2/common/015_realpath.patch Patch for OpenBSD 3.3: ftp://ftp.OpenBSD.org/pub/OpenBSD/patches/3.3/common/001_realpath.patch For versions of OpenBSD prior to 3.2, users may simply fetch the current revision of realpath.c from: ftp://ftp.OpenBSD.org/pub/OpenBSD/src/lib/libc/stdlib/realpath.c then rebuild and install libc with the new realpath.c. For more details, see the description of the wu-ftpd fp_realpath bug: http://isec.pl/vulnerabilities/isec-0011-wu-ftpd.txt - --------------------------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 auscert@auscert.org.au 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. The decision to follow or act on information or advice contained in this security bulletin is the responsibility of each user or organisation, and should be considered in accordance with your organisation's site policies and procedures. AusCERT takes no responsibility for consequences which may arise from following or acting on information or advice contained in this security bulletin. NOTE: This is only the original release of the security bulletin. It may not be updated when updates to the original are made. If downloading at a later date, it is recommended that the bulletin is retrieved directly from the author's website to ensure that the information is still current. Contact information for the authors of the original document is included in the Security Bulletin above. If you have any questions or need further information, please contact them directly. Previous advisories and external security bulletins can be retrieved from: http://www.auscert.org.au/render.html?cid=1980 If you believe that your computer system has been compromised or attacked in any way, we encourage you to let us know by completing the secure National IT Incident Reporting Form at: http://www.auscert.org.au/render.html?it=3192 Internet Email: auscert@auscert.org.au 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----- Comment: http://www.auscert.org.au/render.html?it=1967 iQCVAwUBPy8kfSh9+71yA2DNAQHLOQQAhLCfyv5vWgGATAvXTMIXGR8t920OVj/a JyxwhJ4RH8x8tBXfGNzNut3LCopN1JUDm1civqM9qraHpGf9AbdxeXBnEZSRoWlH llN0ZuPurcqpfdqTvsF8ZzyexUo5QQrOy5h5gbc0DpCTglVkBFuGQeaZ9znWFEty uxZChlY1ZOM= =gGS0 -----END PGP SIGNATURE-----