PR07-38: XSS on sIFR Vulnerability Found: 12 November 2007 Vendor contacted: 19 November 2007 Vulnerability fixed: The issue remains unfixed. The developer of sIFR was contacted several times but did not respond. Severity: Medium Successfully tested on: sIFR 2.0.2 Description: Sites using sIFR to render fonts/text are vulnerable to a vanilla XSS within the "txt" parameter processed by the actionscript in the '<fontname>.swf' flash file. Note: the victim user does NOT need to be authenticated for this vulnerability to be exploitable. HTML injection PoC: Provided the victim is tricked to load the following URL, he/she would be redirected to a third-party site. https://target.tld/<fontname>.swf?txt=<a href="http://www.procheckup.com">click me!</a> XSS PoC: http://target.tld/fonts/FuturaLt.swf?txt=%3Ca%20href=%22javascript:alert (document.cookie)%22%3Eclick%20me!%3C/a%3E&textalign=left&offsetTop=-2&t extcolor= Consequences: An attacker may be able to cause execution of malicious scripting code in the browser of a user who clicks on a link to the target website, or visits a malicious website that requests such link. This type of attack can result in non-persistent defacement of the target site, or the redirection of confidential information (i.e.: session IDs) to unauthorised third parties. References: http://www.procheckup.com/Vulnerabilities.php http://www.mikeindustries.com/sifr Credits: Jan Fry of ProCheckUp Ltd (www.procheckup.com) Legal: Copyright 2008 Procheckup Ltd. All rights reserved. Permission is granted for copying and circulating this Bulletin to the Internet community for the purpose of alerting them to problems, if and only if, the Bulletin is not edited or changed in any way, is attributed to Procheckup, and provided such reproduction and/or distribution is performed for non-commercial purposes. Any other use of this information is prohibited. Procheckup is not liable for any misuse of this information by any third party.