WebSVN <= 2.0 Multiple Vulnerabilities October 20, 2008 Vendor : Tim Armes URL : http://websvn.tigris.org Version : WebSVN <= 2.0 Risk : Multiple Vulnerabilities Description: WebSVN is an online SVN repository viewer. The description taken from the project website reads "WebSVN offers a view onto your subversion repositories that's been designed to reflect the Subversion methodology. You can view the log of any file or directory and see a list of all the files changed, added or deleted in any given revision. You can also view the differences between 2 versions of a file so as to see exactly what was changed in a particular revision." Unfortunately there are a several issues in WebSVN may allow for an attacker to conduct cross site scripting attacks, and create arbitrary files. There is also a code execution issue in the v1 branch. Cross Site Scripting There is a Cross Site Scripting issue in WebSVN due to the unsafe usage of the PHP_SELF server variable within the getParameterisedSelfUrl() function. /index.php/"><script>alert(document.cookie);</script> A url like the one above would display a JavaScript alert window containing the cookie data of any set cookies for the domain. File Handling Issues: There are some file handling issues in the RSS functionality used by WebSVN. The issue is caused by the following bit of code taken from rss.php, and allows arbitrary file operations to be executed. // Cachename reflecting full path to and rev for rssfeed. Must end with xml to work $cachename = strtr(getFullURL($listurl), ":/\\?", "____"); $cachename = $locwebsvnreal.DIRECTORY_SEPARATOR.'cache'.DIRECTORY_SEPARATOR. $cachename.@$_REQUEST['rev'].'_rssfeed.xml'; As we can see from the above bit of code, the "rev" request variable is never properly sanitized. in order to exploit this issue an attacker would have to first send a valid "rev" parameter to rss.php, and then traverse the known location. /rss.php?rev=1_rssfeed.xml/../test.php%00 So, if the "rev" parameter was initially set to the number one, then to create a file called test.php in the root web directory a request like the one above would have to be made. PHP Code Execution: There is an arbitrary php code execution issue in the 1.* branch of WebSVN due to the unsafe use of preg_replace evaluation when parsing anchor tags and the like. // Replace any usernames $ret = preg_replace("#\[:nom:([^\]]*)\]#e", "username(0, trim(\"\\1\"))", $ret); The above code can be found within the create_anchors() function located in the utils.inc file. Since this function uses double quotes, instead of single quotes in the evaluated code, php code execution is possible via complex variable evaluation. [:nom:{${phpinfo()}}] Even though this is not the current version, there is still many 1.* installations being used as seen in the search below. http://www.google.com/search?q=%22powered+by+websvn+v1*%22 Solution: Unfortunately the developers have been mostly unresponsive to any correspondence. The original bug report filed over a month ago can be found at the link below. http://websvn.tigris.org/issues/show_bug.cgi?id=179 Even before this bug report was filed, any attempts made to contact the developers were unsuccessful. Credits: James Bercegay of the GulfTech Security Research Team