-----BEGIN PGP SIGNED MESSAGE----- NetBSD Security Advisory 2003-011 ================================= Topic: off-by-one error in realpath(3) Version: NetBSD-current: source prior to August 4, 2003 NetBSD 1.6.1: affected NetBSD 1.6: affected NetBSD-1.5.3: affected NetBSD-1.5.2: affected NetBSD-1.5.1: affected NetBSD-1.5: affected Severity: Possible remote buffer overrun/root compromise Fixed: NetBSD-current: August 4, 2003 NetBSD-1.6 branch: August 5, 2003 (1.6.2 will include the fix) NetBSD-1.5 branch: Awaiting pullups Abstract ======== In the library function realpath(3), there was a string manipulation mistake which could lead to 1-byte buffer overrun. realpath(3) is being used by important network daemons such as ftpd(8), therefore the vulnerability could be remotely exploitable. Note: The same error remained in a derived function in the distribution of the wu-ftpd server (Not part of NetBSD's base system). This information has been available to the general public for a matter of days now. Exploits have been released against wu-ftpd. They are probably being written against other affected services as well. If you offer any of the affected services, you are advised to patch your system immediately. Technical Details ================= http://www.kb.cert.org/vuls/id/743092 Binaries in the NetBSD base system which use realpath(3) include: /bin/systrace /usr/libexec/ftpd (*) /sbin/mount /sbin/umount /usr/sbin/mountd (*) /usr/bin/ssh /usr/sbin/sshd (*) /usr/libexec/sftp-server (*) /usr/sbin/bootpd (*) Binaries marked (*) listen on network interfaces, and could be remotely exploitable. Solutions and Workarounds ========================= To fix this vulnerability you will need to upgrade your libc. The following instructions describe how to upgrade your libc binaries by updating your source tree and rebuilding and installing a new version of libc. Note that all statically-linked binaries, such as the following, must be rebuilt: - - binaries under /sbin and /bin for 1.5 and 1.6-based systems - - binaries under /rescue for NetBSD-current systems - - statically-linked binaries built by pkgsrc Also, running instances of daemons must be restarted, if you do not plan to reboot the machine after the update of libc. * NetBSD-current: Systems running NetBSD-current dated from before 2003-08-03 should be upgraded to NetBSD-current dated 2003-08-04 or later. The following directories need to be updated from the netbsd-current CVS branch (aka HEAD): lib/libc To update from CVS, re-build, and re-install libc and rescue: # cd src # cvs update -d -P lib/libc # cd lib/libc # make USETOOLS=no cleandir dependall # make USETOOLS=no install # cd ../../rescue # make USETOOLS=no cleandir dependall # make USETOOLS=no install (then, reboot, or restart affected daemons) * NetBSD 1.6, 1.6.1: The binary distributions of NetBSD 1.6 and 1.6.1 are vulnerable. Systems running NetBSD 1.6 sources dated from before 2003-08-04 should be upgraded from NetBSD 1.6 sources dated 2003-08-05 or later. NetBSD 1.6.2 will include the fix. The following directories need to be updated from the netbsd-1-6 CVS branch: lib/libc To update from CVS, re-build, and re-install libc and static binaries: # cd src # cvs update -d -P -r netbsd-1-6 lib/libc # cd lib/libc # make USETOOLS=no cleandir dependall # make USETOOLS=no install # cd ../../sbin # make USETOOLS=no cleandir dependall # make USETOOLS=no install # cd ../bin # make USETOOLS=no cleandir dependall # make USETOOLS=no install (then, reboot, or restart affected daemons) Alternatively, apply the following patch (with potential offset differences): ftp://ftp.netbsd.org/pub/NetBSD/security/patches/SA2003-011-realpath.patch To patch, re-build and re-install libc, and static binaries: # cd src # patch < /path/to/SA2003-011-realpath.patch # cd lib/libc # make USETOOLS=no cleandir dependall # make USETOOLS=no install # cd ../../sbin # make USETOOLS=no cleandir dependall # make USETOOLS=no install # cd ../bin # make USETOOLS=no cleandir dependall # make USETOOLS=no install (then, reboot, or restart affected daemons) * NetBSD 1.5, 1.5.1, 1.5.2, 1.5.3: The binary distributions of NetBSD 1.5, 1.5.1, 1.5.2, and 1.5.3 are vulnerable. Changes have not yet been pulled up to the 1.5 source branch. Apply the following patch (with potential offset differences): ftp://ftp.netbsd.org/pub/NetBSD/security/patches/SA2003-011-realpath.patch To patch, re-build and re-install libc, and static binaries: # cd src # patch < /path/to/SA2003-011-realpath.patch # cd lib/libc # make USETOOLS=no cleandir dependall # make USETOOLS=no install # cd ../../sbin # make USETOOLS=no cleandir dependall # make USETOOLS=no install # cd ../bin # make USETOOLS=no cleandir dependall # make USETOOLS=no install (then, reboot, or restart affected daemons) Thanks To ========= CERT Revision History ================ 2003-08-04 Initial release More Information ================ Advisories may be updated as new information becomes available. The most recent version of this advisory (PGP signed) can be found at ftp://ftp.NetBSD.org/pub/NetBSD/security/advisories/NetBSD-SA2003-011.txt.asc Information about NetBSD and NetBSD security can be found at http://www.NetBSD.org/ and http://www.NetBSD.org/Security/. Copyright 2003, The NetBSD Foundation, Inc. All Rights Reserved. Redistribution permitted only in full, unmodified form. $NetBSD: NetBSD-SA2003-011.txt,v 1.7 2003/08/04 16:02:47 david Exp $ -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.0.6 (NetBSD) Comment: For info see http://www.gnupg.org iQCVAwUBPy6EcD5Ru2/4N2IFAQGJfgP9HXf/mfaGmp9y22PlfA+mxlTiTfb/9N8H ovrKNKiETzFTSr1Ni/l4pqNrkYDRqyP1J4VnS/6wv1ewDYmIzXW1c98gM7+m792l rgZSkaDWxLyPRUhQ8N3BLJKMHvMRdNWPuYwyL76QMVVVFmUo8vSlcH8PRNJrjD8K FIhI6NQ3/+Q= =do/K -----END PGP SIGNATURE-----
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