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-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 =========================================================================== AUSCERT External Security Bulletin Redistribution ESB-2009.1109 SHA2 implementation potential buffer overflow 29 July 2009 =========================================================================== AusCERT Security Bulletin Summary --------------------------------- Product: SHA2 Publisher: NetBSD Operating System: NetBSD UNIX variants (UNIX, Linux, OSX) Impact/Access: Denial of Service -- Unknown/Unspecified Resolution: Patch Original Bulletin: http://ftp.NetBSD.org/pub/NetBSD/security/advisories/NetBSD-SA2009-012.txt.asc Comment: This advisory references vulnerabilities in products which run on platforms other than NetBSD. It is recommended that administrators running SHA2 check for an updated version of the software for their operating system. - --------------------------BEGIN INCLUDED TEXT-------------------- - -----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 NetBSD Security Advisory 2009-012 ================================= Topic: SHA2 implementation potential buffer overflow Version: NetBSD-current: affected prior to 2009-05-26 NetBSD 5.0: affected NetBSD 4.0.*: affected NetBSD 4.0: affected Severity: Denial of Service Fixed: NetBSD-current: May 26, 2009 NetBSD-5-0 branch: Jul 11, 2009 NetBSD-5 branch: Jul 11, 2009 NetBSD-4-0 branch: Jul 22, 2009 NetBSD-4 branch: Jul 22, 2009 Please note that NetBSD releases prior to 4.0 are no longer supported. It is recommended that all users upgrade to a supported release. Abstract ======== An error initializing a SHA2 context causes vulnerable applications using libcrypto to suffer from a 4- or 8-byte buffer overflow (for SHA256 and SHA512 correspondingly) with fixed content, potentially causing applications to crash. Technical Details ================= A program using the SHA2 implementation from sys/sha2.h in NetBSD and linking against libcrypto is vulnerable to a 4- or 8-byte buffer overflow (for SHA256 and SHA512 correspondingly) with fixed content. The overflow occurs at the time the hash init function is called (e.g. SHA256_Init). The init functions then pass the wrong size for the context as an argument to the memset function which then overwrites 4 bytes of the memory buffer located after the one holding the context. In the NetBSD base system, this affects the libssh library as well as the pkg_install framework. In libssh, the overflow occurs on the heap of the program using it, in pkg_install a stack overflow occurs. Solutions and Workarounds ========================= A workaround for this issue for programs in the NetBSD base system is to disable SHA256 as a HMAC for the secure shell and to avoid using the audit facility as well as signed packages. To determine whether or not a package is signed, run the command % tar tzf package.tgz on the package. If the first file of the package is +PKG_HASH, then the package is signed. The following instructions describe how to upgrade your libcrypto and libc binaries by updating your source tree and rebuilding and installing a new version of the three facilities. * NetBSD-current: Systems running NetBSD-current dated from before 2009-05-26 should be upgraded to NetBSD-current dated 2009-05-27 or later. The following files/directories need to be updated from the netbsd-current CVS branch (aka HEAD): common/lib/libc/hash/sha2 distrib/sets/lists lib/libc lib/libcrypto sys/sys To update from CVS, re-build, and re-install lorem: # cd src # cvs update -d -P common/lib/libc/hash/sha2 # cvs update -d -P distrib/sets/lists # cvs update -d -P lib/libc # cvs update -d -P lib/libcrypto # cvs update -d -P sys/sys # cd sys/sys # make USETOOLS=no cleandir # make USETOOLS=no includes # cd ../../lib/libc # make USETOOLS=no cleandir dependall # make USETOOLS=no install # cd ../libcrypt # make USETOOLS=no cleandir dependall # make USETOOLS=no install # cd ../libcrypto # make USETOOLS=no cleandir dependall # make USETOOLS=no install * NetBSD 5.*: Systems running NetBSD 5.* sources dated from before 2009-07-11 should be upgraded from NetBSD 5.* sources dated 2009-07-12 or later. The following files/directories need to be updated from the netbsd-5 or netbsd-5-0 branches: common/lib/libc/hash/sha2 distrib/sets/lists lib/libc lib/libcrypto sys/sys To update from CVS, re-build, and re-install libc and libcrypto: # cd src # cvs update -r <branch_name> -d -P common/lib/libc/hash/sha2 # cvs update -r <branch_name> -d -P distrib/sets/lists # cvs update -r <branch_name> -d -P lib/libc # cvs update -r <branch_name> -d -P lib/libcrypto # cvs update -r <branch_name> -d -P sys/sys # cd sys/sys # make USETOOLS=no cleandir # make USETOOLS=no includes # cd ../../lib/libc # make USETOOLS=no cleandir dependall # make USETOOLS=no install # cd ../libcrypt # make USETOOLS=no cleandir dependall # make USETOOLS=no install # cd ../libcrypto # make USETOOLS=no cleandir dependall # make USETOOLS=no install * NetBSD 4.*: Systems running NetBSD 4.* sources dated from before 2009-07-22 should be upgraded from NetBSD 4.* sources dated 2009-07-23 or later. The following files/directories need to be updated from the netbsd-4 or netbsd-4-0 branches: common/lib/libc/hash/sha2 distrib/sets/lists lib/libc lib/libcrypto sys/sys To update from CVS, re-build, and re-install libc and libcrypto: # cd src # cvs update -r <branch_name> -d -P common/lib/libc/hash/sha2 # cvs update -r <branch_name> -d -P distrib/sets/lists # cvs update -r <branch_name> -d -P lib/libc # cvs update -r <branch_name> -d -P lib/libcrypto # cvs update -r <branch_name> -d -P sys/sys # cd sys/sys # make USETOOLS=no cleandir # make USETOOLS=no includes # cd ../../lib/libc # make USETOOLS=no cleandir dependall # make USETOOLS=no install # cd ../libcrypt # make USETOOLS=no cleandir dependall # make USETOOLS=no install # cd ../libcrypto # make USETOOLS=no cleandir dependall # make USETOOLS=no install Thanks To ========= Joerg Sonnenberger for finding, reporting and fixing the issue. Revision History ================ 2009-07-28 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 http://ftp.NetBSD.org/pub/NetBSD/security/advisories/NetBSD-SA2009-012.txt.asc Information about NetBSD and NetBSD security can be found at http://www.NetBSD.org/ and http://www.NetBSD.org/Security/. Copyright 2009, The NetBSD Foundation, Inc. All Rights Reserved. Redistribution permitted only in full, unmodified form. $NetBSD: NetBSD-SA2009-012.txt,v 1.1 2009/07/28 18:29:29 tonnerre Exp $ - -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.9 (NetBSD) iQIcBAEBAgAGBQJKb0ijAAoJEAZJc6xMSnBuBEEP+wa1ybcKmHkq16evmfBdGIpM 9Z7fVSvx5fDHMvUDGKL5tST/CIoRU379yiBIj/VS0tlUV9TLo1TPdrLO9XON0ara CaIP3DK766+hjya0PwuVuy8yVhUQ6Dz2rKTBjSpmz38qv8RfvR4G6iwF3W6YNvNu pF3vjEJIbQdT6Fen3pzb4D9aiQ6SvEZdknGGR2HmebY2ig4un+bsIJc3x+Iv87Iw qpuJ6KQSnfLxx5qFVO5Sax8SNdL3VmQQcFhVgO3tg/ddcFUVwngXS2Wg9ChczQWt 7wM7OVwXOL1Vr0s2NcRlsIppHXvKRQxu54CuEQM6gsPcleJhsBVFo9/AbeSw4SAx rLiR/jQ6vsC9/28ZpKGQkrtnf5fxP2R7uQIN2nylCiB+s5UDmAHAYTt1tSTMt4ou +xgCX0OnE9iB68FoJYq1YjHMc3n4GclJz3lijXsRBzgGaSHZJc3ywYtO6puS8yUI mXKWPdGthCDVXWiKUOBZYcuS4dv7RoA+VhI3Q1P/kwFQ9xXqb9XWSQYmLycxleA8 BjjSEuIlw5tdAnufDJA8ZRXl4gP0qhrKfPtyYkLUj6pezcyPU1QD61yK0euMr3sq lO97lYhYqtc2gMJaOgVYoHUqbsemuRNEOdHMBeqIoC8MYYH5La6Tuub26Dwz7eDV Mxw6htX0zEm1S/1ld7ne =GZuc - -----END PGP SIGNATURE----- - --------------------------END INCLUDED TEXT-------------------- You have received this e-mail bulletin as a result of your organisation's registration with AusCERT. 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On call after hours for member emergencies only. =========================================================================== -----BEGIN PGP SIGNATURE----- Comment: http://www.auscert.org.au/render.html?it=1967 iD8DBQFKb9dONVH5XJJInbgRAkjyAJ9oycvmKpL3HPe9yGPhQwrX92p8KACfUbGr xzh7rq07GPhXXWcj8Lq6Lrs= =B/vH -----END PGP SIGNATURE-----