ZDI-10-027: Skype Protocol Handler datapath Argument Injection Remote Code Execution Vulnerability
http://www.zerodayinitiative.com/advisories/ZDI-10-027
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 8328. 
For further product information on the TippingPoint IPS, visit:

    http://www.tippingpoint.com

-- Vulnerability Details:
This vulnerability allows remote attackers to execute arbitrary code 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 with how the OS web-browser passes command line
arguments to Skype through the registered 'skype:' protocol handler.
Insufficient sanity checking to the /datapath argument allows an
attacker to construct a link that will execute Skype with arbitrary
arguments. This can be abused to specify a remote configuration storage
directory which can be leveraged to glean target user credentials.

-- Vendor Response:
Skype has issued an update that corrects this vulnerability. More
details can be found at:

http://share.skype.com/sites/garage/2010/03/10/ReleaseNotes_4.2.0.155.pdf

-- 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 overlap with http://seclists.org/fulldisclosure/2010/Mar/207 issue is resolved in latest version of Skype.

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

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