|Lotus Notes/Domino Web Retriever HTTP Status Buffer
Author : Rapid 7 Security Advisories - firstname.lastname@example.org
1. Affected system(s):
o Lotus Notes/Domino R4.5 server and client
o Lotus Notes/Domino R4.6 server and client
o Lotus Notes/Domino R5 server and client
o Lotus Notes/Domino R6 beta (pre-Gold) server and client
o Lotus Notes/Domino R6.0 Gold
o Lotus Notes/Domino R6.0.1
o Lotus Notes/Domino R5.0.12
The Lotus Notes/Domino Web Retriever task is responsible for
retrieving web pages on behalf of Notes users who want to access the
web via their Notes server.
The Web Retriever program will crash when it receives an overly long
HTTP status line from a remote web server.
If the Web Retriever is running as a server task, the crash will
cause a denial of service on the server.
If the Web Retriever is running locally on a client, the crash will
bring down the Notes client with it.
3. Vendor status and information
Lotus was notified and they have fixed this vulnerability. Lotus is
tracking this issue with SPR #KSPR5DFJTR.  IBM has also prepared
Technote #1105060, which discusses this vulnerability. 
See the References section for more information.
Users running R5 should upgrade to Notes R5.0.12. Users of R6
pre-Gold releases should upgrade R6.0 Gold or higher. 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):
As a workaround, you can disable the Web Retriever task on the
server. To do this, first remove the 'Web' entry from the
ServerTasks line in the server's NOTES.INI file, then issue the
'tell web quit' command at the server console.
In addition, consider removing the Web Retrieval database (typically
/WEB.NSF) or lock down its ACL so that no users can access it. If
the Web Retriever is disabled, users probably do not need access to
Notes clients will be vulnerable to this if they are configured to
use the Notes web browser instead of an external browser program.
This option can be viewed in the Internet browser section of the
current Location document.
5. Detailed analysis
By issuing an overly long status message in its HTTP response, a
remote server can crash the Web Retriever process. The response
line consists of the standard HTTP version and code followed by an
overly long (~6000 bytes) status message, followed by two carriage
HTTP/1.1 200 Ax6000<crlf><crlf>
A response length of around 6000 bytes is usually sufficient to crash
the Web Retriever. Using a somewhat smaller buffer will still
corrupt the heap, but the crash may not occur until the corrupted
portions of the heap are later used.
 Lotus SPR #KSPR5DFJTR (URL wrapped)
 IBM Technote #1105060 (URL wrapped)
7. Contact Information
Rapid7 Security Advisories
Phone: +1 (212) 558-8700
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