Full_Name: Cameron Hotchkies Version: 2.3.41 OS: Gentoo Linux URL: ftp://ftp.openldap.org/incoming/ Submission from: (NULL) (66.179.208.36) This vulnerability allows remote attackers to deny services on vulnerable installations of OpenLDAP. Authentication is not required to exploit this vulnerability. The specific flaw exists in the decoding of ASN.1 BER network datagrams. When the size of a BerElement is specified incorrectly, the application will trigger an assert(), leading to abnormal program termination. Tech Details: The code exhibiting the problem is located in the function ber_get_next() function in "libraries/liblber/io.c" . The function fails to handle properly BER encoding of an element (tag + length + content) that contains: * exactly 4 bytes long "multi-byte tag" * exactly 4 bytes long "multi-byte size" The total size of the resulting encoding equals to the size of the BerElement structure buffer plus one byte. This causes the function returns indicating that more data are needed, but leaves the read-pointer pointing right at the end of the buffer, which is not permitted. Subsequent calls to the function result in an assertion failure: assert( 0 ); /* ber structure is messed up ?*/ Example Exploitation: > slapd -h ldap:// -d511 & ... > xxd packet 0000000: ffff ff00 8441 4243 44 .....ABCD > nc localhost 389 < packet
zdi-disclosures@tippingpoint.com wrote: > Full_Name: Cameron Hotchkies > Version: 2.3.41 > OS: Gentoo Linux > URL: ftp://ftp.openldap.org/incoming/ > Submission from: (NULL) (66.179.208.36) > > > This vulnerability allows remote attackers to deny services on vulnerable > installations of OpenLDAP. Authentication is not required to exploit this > vulnerability. Thanks for the report, a fix is now in HEAD. Please test. > The specific flaw exists in the decoding of ASN.1 BER network datagrams. When > the size of a BerElement is specified incorrectly, the application will trigger > an assert(), leading to abnormal program termination. > Tech Details: > > The code exhibiting the problem is located in the function ber_get_next() > function in "libraries/liblber/io.c" . > > The function fails to handle properly BER encoding of an element (tag + length + > content) that contains: > > * exactly 4 bytes long "multi-byte tag" > * exactly 4 bytes long "multi-byte size" > > The total size of the resulting encoding equals to the size of the BerElement > structure buffer plus one byte. This causes the function returns indicating that > more data are needed, but leaves the read-pointer pointing right at the end of > the buffer, which is not permitted. > > Subsequent calls to the function result in an assertion failure: > > assert( 0 ); /* ber structure is messed up ?*/ > > Example Exploitation: > > > slapd -h ldap:// -d511& > ... > > xxd packet > 0000000: ffff ff00 8441 4243 44 .....ABCD > > nc localhost 389< packet > > > -- -- Howard Chu CTO, Symas Corp. http://www.symas.com Director, Highland Sun http://highlandsun.com/hyc/ Chief Architect, OpenLDAP http://www.openldap.org/project/
Howard Chu wrote: > zdi-disclosures@tippingpoint.com wrote: >> Full_Name: Cameron Hotchkies >> Version: 2.3.41 >> OS: Gentoo Linux >> URL: ftp://ftp.openldap.org/incoming/ >> Submission from: (NULL) (66.179.208.36) >> >> >> This vulnerability allows remote attackers to deny services on vulnerable >> installations of OpenLDAP. Authentication is not required to exploit this >> vulnerability. > > Thanks for the report, a fix is now in HEAD. Please test. For future reference, it looks like this may have crept in in 2001, rev 1.88/ITS#2465... -- -- Howard Chu CTO, Symas Corp. http://www.symas.com Director, Highland Sun http://highlandsun.com/hyc/ Chief Architect, OpenLDAP http://www.openldap.org/project/
changed notes changed state Open to Test moved from Incoming to Software Bugs
--On Friday, June 27, 2008 12:41 AM +0000 hyc@symas.com wrote: > Howard Chu wrote: >> zdi-disclosures@tippingpoint.com wrote: >>> Full_Name: Cameron Hotchkies >>> Version: 2.3.41 >>> OS: Gentoo Linux >>> URL: ftp://ftp.openldap.org/incoming/ >>> Submission from: (NULL) (66.179.208.36) >>> >>> >>> This vulnerability allows remote attackers to deny services on >>> vulnerable installations of OpenLDAP. Authentication is not required to >>> exploit this vulnerability. >> >> Thanks for the report, a fix is now in HEAD. Please test. > > For future reference, it looks like this may have crept in in 2001, rev > 1.88/ITS#2465... 2003, not 2001? 1.88 Thu Apr 24 00:10:18 2003 UTC; 5 years, 2 months ago by hyc Changed since 1.87: +3 -3 lines Diffs to 1.87 (colored diff) ITS#2465 fix? ber_get_next must read at least sizeof(tag)+sizeof(len) which should be at most 8 bytes. However if we read more than the minimum message length, we have a problem because we steal bytes from any following message, and there is no buffer mechanism to push back excess data. The shortest legitimate message is Unbind at 7 bytes, but there shouldn't be anything following it. Abandon at 8 bytes is next, so always requesting at least 8 bytes should be safe. Always requesting 9 was a problem. Please double-check these assumptions... -- Quanah Gibson-Mount Principal Software Engineer Zimbra, Inc -------------------- Zimbra :: the leader in open source messaging and collaboration
changed notes changed state Test to Release
changed state Release to Closed
fixed in HEAD/RE24/RE23