cbcvebase.
CVE-2011-3368
published 2011-10-05

CVE-2011-3368: The mod_proxy module in the Apache HTTP Server 1.3.x through 1.3.42, 2.0.x through 2.0.64, and 2.2.x through 2.2.21 does not properly interact with use of (1)…

PriorityP357medium5CVSS 2.0
AVNACLAuNCPINAN
EXPLOIT
EPSS
90.73%
99.8th percentile
The mod_proxy module in the Apache HTTP Server 1.3.x through 1.3.42, 2.0.x through 2.0.64, and 2.2.x through 2.2.21 does not properly interact with use of (1) RewriteRule and (2) ProxyPassMatch pattern matches for configuration of a reverse proxy, which allows remote attackers to send requests to intranet servers via a malformed URI containing an initial @ (at sign) character.

Affected

123 ranges· showing 25
VendorProductVersion rangeFixed in
apachehttp_server
apachehttp_server
apachehttp_server
apachehttp_server
apachehttp_server
apachehttp_server
apachehttp_server
apachehttp_server
apachehttp_server
apachehttp_server
apachehttp_server
apachehttp_server
apachehttp_server
apachehttp_server
apachehttp_server
apachehttp_server
apachehttp_server
apachehttp_server
apachehttp_server
apachehttp_server
apachehttp_server
apachehttp_server
apachehttp_server
apachehttp_server
apachehttp_server

Detection & IOCsextracted from sources · hover to see the quote

commandGET <url>@<internal_target>:<internal_port>/<resource> HTTP/1.1
  • Detect HTTP requests where the Request-URI contains an '@' (at sign) character at or near the beginning, which is the malformed URI pattern used to bypass mod_proxy reverse proxy controls and redirect requests to intranet servers.
  • Monitor for HTTP 502 (Bad Gateway) responses from the Apache reverse proxy in response to requests containing '@' in the URI — the exploit PoC treats a 502 as a positive indicator of a successful bypass attempt (server attempted to proxy the request).
  • The Metasploit scanner module (auxiliary/scanner/http/rewrite_proxy_bypass) detects vulnerable servers by forcing a request with an invalid domain name and checking for a 502 response as a bypass indicator; baseline status codes are compared to avoid false positives.
  • CVE-2011-3639 and CVE-2011-4317 are incomplete-fix variants of this vulnerability; also inspect for URIs containing '@' combined with ':' in invalid positions (CVE-2011-4317) or HTTP/0.9 requests with '@' in the URI (CVE-2011-3639).
  • ·The vulnerability only affects Apache deployments where mod_proxy is configured with RewriteRule or ProxyPassMatch directives for reverse proxy use; servers not using these directives in a reverse proxy configuration are not exposed.
  • ·Red Hat Enterprise Linux 4 and 5 are not affected due to differences in apr-util's apr_uri_parse() implementation, so detection rules targeting those platforms may produce false negatives.
  • ·The Metasploit scanner warns that if the baseline status code already matches the test (502) status code, the injection attempt is skipped to avoid false positives; manual verification with VERBOSE mode is recommended.

CVSS provenance

nvdv2.05.0MEDIUMAV:N/AC:L/Au:N/C:P/I:N/A:N
osv5.0MEDIUM
vendor_debian5.0MEDIUM
vendor_redhat5.0MEDIUM
vendor_ubuntu4.3MEDIUM
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