ZDI-10-028: Skype URI Processing Arbitrary XML File Deletion Vulnerability
http://www.zerodayinitiative.com/advisories/ZDI-10-028
March 11, 2010

-- Affected Vendors:
Skype

-- Affected Products:
Skype

-- TippingPoint(TM) IPS Customer Protection:
TippingPoint IPS customers have been protected against this
vulnerability by Digital Vaccine protection filter ID 8329. 
For further product information on the TippingPoint IPS, visit:

    http://www.tippingpoint.com

-- Vulnerability Details:
This vulnerability allows remote attackers to remove arbitrary XML files
on vulnerable installations of Skype. User interaction is required to
exploit this vulnerability in that the target must visit a malicious
page.

The specific flaw exists in Skype's handling of the 'skype-plugin:'
protocol. An attacker can specify a malicious URI, that upon clicking,
will trigger the deletion of an arbitrary attacker specified XML file.

-- Vendor Response:
Not available.

-- Disclosure Timeline:
2009-07-14 - Initial report to vendor, no response.
2010-01-07 - Follow-up report, again no response.
2010-01-11 - Received support e-mail with update notice from Skype.
2010-01-11 - We responded the same day stating that the new version does not address our reported bugs.
2010-01-12 - Skype requests more details, specifically a screen shot.
2010-01-12 - We responded the same day. No follow-up response from Skype.
2010-01-19 - We followed up with Skype again who has not been heard from since.
2010-03-11 - Uncoordinated release of public advisory due to failure to communicate, issue remains unresolved.

-- Credit:
This vulnerability was discovered by:
    * rgod

-- About the Zero Day Initiative (ZDI):
Established by TippingPoint, The Zero Day Initiative (ZDI) represents 
a best-of-breed model for rewarding security researchers for responsibly
disclosing discovered vulnerabilities.

Researchers interested in getting paid for their security research
through the ZDI can find more information and sign-up at:

    http://www.zerodayinitiative.com

The ZDI is unique in how the acquired vulnerability information is
used. TippingPoint does not re-sell the vulnerability details or any
exploit code. Instead, upon notifying the affected product vendor,
TippingPoint provides its customers with zero day protection through
its intrusion prevention technology. Explicit details regarding the
specifics of the vulnerability are not exposed to any parties until
an official vendor patch is publicly available. Furthermore, with the
altruistic aim of helping to secure a broader user base, TippingPoint
provides this vulnerability information confidentially to security
vendors (including competitors) who have a vulnerability protection or
mitigation product.

Our vulnerability disclosure policy is available online at:

    http://www.zerodayinitiative.com/advisories/disclosure_policy/

Follow the ZDI on Twitter:

    http://twitter.com/thezdi