IOActive Security Advisory Title: Multiple Buffer Overflows in Legacy mod_jk2 <= 2.0.3-DEV Severity: High Date Discovered: 05.01.2007 Date Reported: 06.27.2007 Date Disclosed: 09.20.2007 Affected Products: mod_jk2 <= v2.0.3-DEV F5 BIG-IP <= 9.2.3.30 (Other versions were not tested) Synopsis: IOActive has discovered a buffer overflow in the Host Header field in the legacy version of the mod_jk2 Apache module (jakarta-tomcat-connectors) which allows for remote code execution in the context of the Apache process. Description: mod_jk2 versions prior to 2.0.4 are vulnerable to multiple stack overflow vulnerabilities. Specifically, IOActive has discovered multiple locations where these vulnerabilities are exploitable via the Host request header in any given request. These overflows all result in remote code execution under the user of the running Apache process. Although a legacy module which is end of life, certain vendors may use this module in their products rendering them vulnerable to remote exploitation. Technical Details: Within the mod_jk2 module, the module registers with Apache a request handler which parses the entire content of the request, specifically the Host headers, in order to determine which Tomcat worker to forward the request to. For example, multiple buffer overflow opportunities exist within the following code segments: native2\common\jk_uriMap.c: line ~269 if (port) { if (vhost) { if (strchr(vhost, ':')) strcpy(hostname, vhost); else sprintf(hostname, "%s:%d", vhost, port); } else sprintf(hostname, "*:%d", port); } else if (vhost) strcpy(hostname, vhost); native2\common\jk_uriMap.c: line ~842 char key[1024]; if (!vhost && !port) return uriMap->vhosts->get(env, uriMap->vhosts, "*"); if (!vhost) vhost = "*"; sprintf(key, "%s:%d", vhost, port); return uriMap->vhcache->get(env, uriMap->vhcache, key); In each of these code segments, exploitable stack overflows on the Host request header are visible. Additionally, in every circumstance, the condition occurs when a Hostname is provided within the Host: Header request which is longer than 1024 characters. Exploitation of these overflows is considered trivial. Remediation: Upgrade to the latest version of the legacy mod_jk2 (mod_jk2 2.0.4) or migrate to the non-legacy reimplementation of this package, the new jakarta-tomcat-connectors, called mod_jk.