cbcvebase.
CVE-2008-3656
published 2008-08-13

CVE-2008-3656: Algorithmic complexity vulnerability in the WEBrick::HTTPUtils.split_header_value function in WEBrick::HTTP::DefaultFileHandler in WEBrick in Ruby 1.8.5 and…

PriorityP354high7.8CVSS 2.0
AVNACLAuNCNINAC
EXPLOIT
EPSS
70.20%
99.3th percentile
Algorithmic complexity vulnerability in the WEBrick::HTTPUtils.split_header_value function in WEBrick::HTTP::DefaultFileHandler in WEBrick in Ruby 1.8.5 and earlier, 1.8.6 through 1.8.6-p286, 1.8.7 through 1.8.7-p71, and 1.9 through r18423 allows context-dependent attackers to cause a denial of service (CPU consumption) via a crafted HTTP request that is processed by a backtracking regular expression.

Affected

12 ranges
VendorProductVersion rangeFixed in
ruby-langruby<= 1.8.5
ruby-langruby
ruby-langruby
ruby-langruby
ruby-langruby
ruby-langruby
ruby-langruby
ruby-langruby
ruby-langruby
ruby-langruby
ruby-langruby
ruby-langwebrick>= 0 < 1.3.11.3.1

Detection & IOCsextracted from sources · hover to see the quote

commandreq['If-None-Match'] = %q{meh=""} + %q{foo="bar" } * 100
  • Detect DoS attempts against WEBrick by monitoring for HTTP requests containing a crafted If-None-Match header with repeated quoted key=value pairs (e.g., many repetitions of foo="bar"), which triggers catastrophic backtracking in WEBrick::HTTPUtils.split_header_value.
  • The vulnerable function is WEBrick::HTTPUtils.split_header_value in WEBrick::HTTP::DefaultFileHandler; alert on abnormally long or repetitive If-None-Match header values in HTTP requests to Ruby WEBrick servers.
  • CPU consumption spike on a WEBrick server process may indicate active exploitation; the attack causes denial of service via a backtracking regular expression triggered by the crafted HTTP request.
  • ·The initial Red Hat patch for CVE-2008-3656 was incomplete and did not fully address the vulnerability; a second CVE (CVE-2008-4310) was assigned for the incomplete fix. Ensure the correct/final patch is applied.
  • ·Affected versions include Ruby 1.8.5 and earlier, 1.8.6 through 1.8.6-p286, 1.8.7 through 1.8.7-p71, and 1.9 through r18423; the vulnerability exists in httputils.rb within WEBrick.

CVSS provenance

nvdv2.07.8HIGHAV:N/AC:L/Au:N/C:N/I:N/A:C
ghsa7.8HIGH
osv7.8HIGH
vendor_redhat7.8HIGH
vendor_ubuntu6.8MEDIUM
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