R7-0010: Buffer Overflow in Lotus Notes Protocol Authentication

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Rapid7 Advisory R7-0010
Buffer Overflow in Lotus Notes Protocol Authentication

Published: March 12, 2003
Revision: 1.0
http://www.rapid7.com/advisories/R7-0010.html

CVE: CAN-2003-0122
Lotus SPR: DBAR5CJJJS
IBM Technote: 1105101
Bugtraq ID: 7037

1. Affected system(s):

   KNOWN VULNERABLE:
   o Lotus Notes R4
   o Lotus Notes R5 up to and including R5.0.11
   o Lotus Notes R6 betas and pre-releases

   NOT VULNERABLE:
   o Lotus Notes R5.0.12
   o Lotus Notes R6.0 Gold
   o Lotus Notes R6.0.1

   UNKNOWN / NOT TESTED:
   o Lotus Notes R3 and earlier

2. Summary

   Lotus Notes and Domino servers support a proprietary protocol called
   NotesRPC, commonly known as the Notes protocol. This protocol is
   usually bound to TCP port 1352, but can also use NetBIOS, Netware
   SPX, Banyan Vines, and modem dialup for transport.

   When a Notes client connects to a Notes server, it authenticates with
   the server to establish a session. This authentication consists of a
   series of exchanges in which the client and server present each other
   with challenges to verify each other's identity.

   It is possible for an unauthenticated client to manipulate the data
   during this exchange to trigger a buffer overflow on the Notes
   server. This allows an attacker to overwrite large sections of the
   heap with arbitrary data. While our testing only covered TCP/IP, we
   believe it is possible for this overflow to be triggered via other
   protocols, including dialup. It is theoretically possible for an
   attacker to supply the data in such a way as to compromise the
   Notes server's security.

3. Vendor status and information

   Lotus
   http://www.lotus.com/
   http://www.ibm.com/

   Lotus was notified and they have fixed this vulnerability. Lotus is
   tracking this issue with SPR #DBAR5CJJJS. [1] IBM has also prepared
   Technote #1105101, which discusses this vulnerability. [2]

   See the References section for more information.

4. Solution

   This vulnerability is fixed in R5.0.12 and R6.0 Gold. Customers
   running R5.0.11 or earlier (or Notes R6 beta) are advised to upgrade.
   R6.0 Gold is not affected, but due to other vulnerabilities
   discovered in R6.0 Gold, you should consider upgrading to R6.0.1,
   which was released in February 2003.

   Domino incremental installers may be downloaded from the following
   URL (which has been wrapped):

   http://www14.software.ibm.com
   /webapp/download/search.jsp?go=y&rs=ESD-DMNTSRVRi&sb=r

   For more information on partial mitigation strategies for this
   and other Notes vulnerabilities (including best practices for
   Internet-facing Domino servers), please see Rapid7's FAQ for
   these vulnerabilities at:

   http://www.rapid7.com/advisories/R7-0010-info.html

5. Detailed analysis

   During NotesRPC authentication, the client sends the server its
   distinguished name (DN). The distinguished name is a string that
   looks like "CN=John Smith/O=Acme/C=US". The DN string is prefixed
   by a 16-bit word that specifies its length. The outer packet
   structure contains a header field that refers to the DN field's
   length (which is the length of the prefix plus the length of the
   DN itself).

   If the length specified in the outer header field is less than or
   equal to the length specified in the DN field, an error occurs in
   the data offset arithmetic such that a total of 65534 bytes are
   copied onto the Notes heap (a proprietary structure managed by
   Notes API calls such as OSMemoryAllocate). An attacker can supply
   all of the bytes to be copied by specifying additional data in the
   packet after the DN.

6. References

   [1] Lotus SPR #DBAR5CJJJS (URL wrapped)
   http://www-10.lotus.com
   /ldd/r5fixlist.nsf/Search?SearchView&Query=DBAR5CJJJS

   [2] IBM Technote #1105101 (URL wrapped)
   http://www-1.ibm.com
   /support/docview.wss?rs=482&q=Domino&uid=swg21105101

7. Contact Information

   Rapid7 Security Advisories
   Email: [email protected]
   Web: http://www.rapid7.com/
   Phone: +1 (212) 558-8700

8. Disclaimer and Copyright

   Rapid7, Inc. is not responsible for the misuse of the information
   provided in our security advisories. These advisories are a service
   to the professional security community. There are NO WARRANTIES
   with regard to this information. Any application or distribution of
   this information constitutes acceptance AS IS, at the user's own
   risk. This information is subject to change without notice.

   This advisory Copyright (C) 2003 Rapid7, Inc. Permission is
   hereby granted to redistribute this advisory, providing that no
   changes are made and that the copyright notices and disclaimers
   remain intact.

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