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Apache httpd: denial of service via mod_proxy_ajp
Synthesis of the vulnerability
When mod_proxy_ajp is used with mod_proxy_balancer, an attacker can use an unknown HTTP method, in order to create a denial of service.
Impacted systems: Apache httpd, OpenView, OpenView NNM, HP-UX, Junos Space, Junos Space Network Management Platform, Mandriva Linux, OpenSolaris, RHEL, Slackware.
Severity of this alert: 2/4.
Consequences of an intrusion: denial of service on service.
Pirate's origin: internet client.
Creation date: 14/09/2011.
Références of this alert: BID-49616, c03011498, c03025215, CERTA-2011-AVI-516, CVE-2011-3348, HPSBMU02704, HPSBUX02707, MDVSA-2011:168, PSN-2013-02-846, RHSA-2011:1391-01, RHSA-2012:0542-01, RHSA-2012:0543-01, SSA:2011-284-01, SSRT100619, SSRT100626, VIGILANCE-VUL-10991.
Description of the vulnerability
The mod_proxy module provides a generic proxy service for Apache httpd. The mod_proxy_ajp module adds the AJP13 (Apache JServe Protocol version 1.3) support, which is used with Tomcat. The mod_proxy_balancer module is used to balance the load between several proxies.
The HTTP protocol defines a list of methods (GET, POST, etc.) which are used in queries.
The ap_proxy_ajp_request() function of the modules/proxy/mod_proxy_ajp.c file does not ignore unknown HTTP methods. However, when mod_proxy_balancer is also used, the associated proxy enters in an error state. Using several queries, an attacker can thus stop all balanced proxies.
When mod_proxy_ajp is used with mod_proxy_balancer, an attacker can therefore use an unknown HTTP method, in order to create a denial of service.
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