Bug 453444 (CVE-2008-2952)

Summary: CVE-2008-2952 OpenLDAP denial-of-service flaw in ASN.1 decoder
Product: [Other] Security Response Reporter: Josh Bressers <bressers>
Component: vulnerabilityAssignee: Red Hat Product Security <security-response-team>
Status: CLOSED ERRATA QA Contact:
Severity: medium Docs Contact:
Priority: medium    
Version: unspecifiedCC: jsafrane, kreilly, psklenar
Target Milestone: ---Keywords: Security
Target Release: ---   
Hardware: All   
OS: Linux   
URL: http://www.openldap.org/its/index.cgi/Software%20Bugs?id=5580;selectid=5580
Fixed In Version: Doc Type: Bug Fix
Doc Text:
Story Points: ---
Clone Of: Environment:
Last Closed: 2008-07-21 10:15:35 UTC Type: ---
Regression: --- Mount Type: ---
Documentation: --- CRM:
Verified Versions: Category: ---
oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: --- Target Upstream Version:
Bug Depends On: 453637, 453638, 453639, 453640, 453726, 453727, 453728    
Bug Blocks:    
Description Flags
Patch from upstream CVE none

Description Josh Bressers 2008-06-30 17:39:52 UTC
A DoS flaw was reported to the OpenLDAP BTS:

The bug states:

This vulnerability allows remote attackers to deny services on vulnerable
installations of OpenLDAP. Authentication is not required to exploit this

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

Comment 1 Josh Bressers 2008-06-30 17:53:21 UTC
Created attachment 310609 [details]
Patch from upstream CVE

This patch came from here:

Comment 2 Josh Bressers 2008-06-30 18:48:49 UTC
The testcase only crashes the Red Hat Enterprise Linux 4 and 5 versions of
openldap.  The 2.1 and 3 versions seem to handle this just fine.

Comment 5 Tomas Hoger 2008-07-02 08:43:41 UTC
Original upstream patch was reported to be broken:


Different patch applied upstream:


Comment 6 Fedora Update System 2008-07-03 03:15:29 UTC
openldap-2.3.39-4.fc8 has been pushed to the Fedora 8 stable repository.  If problems still persist, please make note of it in this bug report.

Comment 7 Fedora Update System 2008-07-03 03:17:16 UTC
openldap-2.4.8-6.fc9 has been pushed to the Fedora 9 stable repository.  If problems still persist, please make note of it in this bug report.

Comment 9 Red Hat Product Security 2008-07-21 10:15:35 UTC
This issue was addressed in:

Red Hat Enterprise Linux:


Comment 10 Tomas Hoger 2008-08-15 06:55:32 UTC
ZDI advisory related to this issue: