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Legacy Apache mod_jk2 Buffer Overflow
------------------------------------------------------------------------
SUMMARY
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.
DETAILS
Vulnerable Systems:
* mod_jk2 version 2.0.3-DEV
* F5 BIG-IP version 9.2.3.30
Immune Systems:
* mod_jk2 version 2.0.4-DEV
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.
ADDITIONAL INFORMATION
The information has been provided by <mailto:advisory@ioactive.com>
IOActive Advisories.
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