In additional response to the iDEFENSE Security Advisory 04.08.03 cited below, the Apache HTTP Server Project has published a specific patch to address this Denial of Service vulnerability for the 2.0.44 server version. The patch may or may not apply to earlier versions of Apache 2.0, and if applied to earlier versions, may or may not fully address the vulnerability. Review was limited to correcting the but in the 2.0.44 release only. The patch can be obtained from; http://www.apache.org/dist/httpd/patches/apply_to_2.0.44/denial_of_service_fix.patch The Apache HTTP Server project continues to caution users to obtain the latest release (2.0.45 at this time) from http://httpd.apache.org/download.cgi to improve stability and obtain the most current bug fixes. As noted in the prior announcement; OS/2 Users of both 2.0.44 and 2.0.45 have an additional Denial of Service vulnerability identified and reported by Robert Howard <rihowardat_private> that be addressed with the next release. Until that time, OS2 users must obtain an additional patch before building Apache release 2.0.45 or prior: http://www.apache.org/dist/httpd/patches/apply_to_2.0.45/os2_filestat_security_fix.patch That is all. At 11:44 AM 4/8/2003, iDEFENSE Labs wrote: >iDEFENSE Security Advisory 04.08.03: >http://www.idefense.com/advisory/04.08.03.txt >Denial of Service in Apache HTTP Server 2.x >April 8, 2003 > >Remote exploitation of a memory leak in the Apache HTTP Server causes the >daemon to over utilize system resources on an affected system. The problem >is HTTP Server's handling of large chunks of consecutive linefeed >characters. The web server allocates an eighty-byte buffer for each >linefeed character without specifying an upper limit for allocation. >Consequently, an attacker can remotely exhaust system resources by >generating many requests containing these characters. >[...] > >V. VENDOR FIX/RESPONSE > >Apache HTTP Server 2.0.45, which fixes this vulnerability, can be >downloaded at http://httpd.apache.org/download.cgi . This release >introduces a limit of 100 blank lines accepted before an HTTP connection >is discarded.
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