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-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 =========================================================================== AUSCERT External Security Bulletin Redistribution ESB-2006.0871 -- [Win][UNIX/Linux] GnuPG 1.4.5 and 2.0.0 buffer overflow vulnerability 29 November 2006 =========================================================================== AusCERT Security Bulletin Summary --------------------------------- Product: GnuPG 2.0.0 and prior GnuPG 1.4.5 and prior Operating System: UNIX variants (UNIX, Linux, OSX) Windows Impact: Execute Arbitrary Code/Commands Access: Remote/Unauthenticated - --------------------------BEGIN INCLUDED TEXT-------------------- GnuPG 1.4 and 2.0 buffer overflow ================================== Summary ======= While fixing a bug reported by Hugh Warrington, a buffer overflow has been identified in all released GnuPG versions. The current versions 1.4.5 and 2.0.0 are affected. A small patch is provided. Please do not send private mail in response to this message. The mailing list gnupg-devel is the best place to discuss this problem (please subscribe first so you don't need moderator approval [1]). Impact ====== When running GnuPG interactively, special crafted messages may be used to crash gpg or gpg2. Running gpg in batch mode, as done by all software using gpg as a backend (e.g. mailers), is not affected by this bug. Exploiting this overflow seems to be possible. gpg-agent, gpgsm, gpgv or other tools from the GnuPG suite are not affected. Solution ======== Apply the following patch to GnuPG. It should apply cleanly to current versions (1.4.5 as well as 2.0.0) but might also work for older versions. 2006-11-27 Werner Koch <wk (at) g10code (dot) com [email concealed]> * openfile.c (ask_outfile_name): Fixed buffer overflow occurring if make_printable_string returns a longer string. Fixes bug 728. - --- g10/openfile.c (revision 4348) +++ g10/openfile.c (working copy) @@ -144,8 +144,8 @@ s = _("Enter new filename"); - - n = strlen(s) + namelen + 10; defname = name && namelen? make_printable_string( name, namelen, 0): NULL; + n = strlen(s) + (defname?strlen (defname):0) + 10; prompt = xmalloc(n); if( defname ) sprintf(prompt, "%s [%s]: ", s, defname ); Background: =========== The code in question has been introduced on July 1, 1999 and is a pretty obvious bug. make_printable_string is supposed to replace possible dangerous characters from a prompt and returns a malloced string. Thus this string may be longer than the orginal one; the buffer for the prompt has only be allocated at the size of the original string - oops. Note, that using snprintf would not have helped in this case. How I wish C-90 had introduced asprintf or at least it would be available on more platforms. The original bug report is at https://bugs.g10code.com/gnupg/issue728 . === [1] See http://lists.gnupg.org/mailman/listinfo/gnupg-devel . - -- Werner Koch <wk (at) gnupg (dot) org [email concealed]> The GnuPG Experts http://g10code.com Join the Fellowship and protect your Freedom! http://www.fsfe.org - --------------------------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. NOTE: Third Party Rights 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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On call after hours for member emergencies only. =========================================================================== -----BEGIN PGP SIGNATURE----- Comment: http://www.auscert.org.au/render.html?it=1967 iQCVAwUBRWzXqCh9+71yA2DNAQJ1+wP/VEqailp5ZQiFgiyWnXQnLvnjvrrli6aH FktOlvimIKRV9IhfbMhi7rxogFGz2hA4a4P9lf68BqJ5OsiBH9p7sPuCbAWMvYJZ G/O8mpCH0+VnzoqcxBKJjAMIzLbG6K+9yYNdBf51YsMiM9aYpfB7TUSgkYlsUqAe lBgZfHfCzd4= =bvbJ -----END PGP SIGNATURE-----