26.10.05

Skype Multiple Buffer Overflow Vulnerabilities

Some vulnerabilities have been reported in Skype, which can be exploited by malicious people to cause a DoS or to compromise a user's system.

Secunia Advisory:SA17305Print Advisory
Release Date:2005-10-25
Last Update:2005-10-26

Critical:
Highly critical
Impact:DoS
System access
Where:From remote
Solution Status:Vendor Patch

Software:Skype for Linux 0.x
Skype for Linux 1.x
Skype for Mac OS X 0.x
Skype for Mac OS X 1.x
Skype for Pocket PC 1.x
Skype for Windows 1.x


Select a product and view a complete list of all Patched/Unpatched Secunia advisories affecting it.

CVE reference:CVE-2005-3265
CVE-2005-3267

Description:
Some vulnerabilities have been reported in Skype, which can be exploited by malicious people to cause a DoS or to compromise a user's system.

1) A boundary error exists when handling Skype-specific URI types e.g. "callto://" and "skype://". This can be exploited to cause a buffer overflow and allows arbitrary code execution when the user clicks on a specially-crafted Skype-specific URL.

The vulnerability is related to:
SA13191

2) A boundary error exists in the handling of VCARD imports. This can be exploited to cause a buffer overflow and allows arbitrary code execution when the user imports a specially-crafted VCARD.

Vulnerability #1 and #2 has been reported in Skype for Windows Release 1.1.*.0 through 1.4.*.83.

3) An integer overflow error exists when allocating memory in response to certain received Skype client network UDP packet. This can be exploited to cause a heap-based buffer overflow via a specially-crafted UDP packet.

Successful exploitation crashes the Skype client. It has been reported that the vulnerability is also exploitable via TCP and allows arbitrary code execution via overwritten function pointers on the heap.

The vulnerability has been reported in the following versions:
* Skype for Windows Release 1.4.*.83 and prior.
* Skype for Mac OS X Release 1.3.*.16 and prior.
* Skype for Linux Release 1.2.*.17 and prior.
* Skype for Pocket PC Release 1.1.*.6 and prior.

Solution:
Update to the fixed version.
http://www.skype.com/download/

Skype for Windows:
Update to Release 1.4.*.84 or later.

Skype for Mac OS X:
Update to Release 1.3.*.17 or later.

Skype for Linux:
Update to Release 1.2.*.18 or later.

Skype for Pocket PC:
Update to Release 1.1.0.20 or later.

Provided and/or discovered by:
1-2) Mark Rowe and Joe Moore, Pentest Limited.
3) Imad Lahoud, EADS Corporate Research Center.

Changelog:
2005-10-25: Updated credit and "Original Advisory" sections.
2005-10-26: Updated "Description" section.
2005-10-26: Vendor releases fixed version for Pocket PC. Updated "Solution Status" and "Solution" sections.

Original Advisory:
Skype:
http://www.skype.com/security/skype-sb-2005-02.html
http://www.skype.com/security/skype-sb-2005-03.html

Pentest Limited:
http://www.pentest.co.uk/documents/ptl-2005-01.html

Other References:
SA13191:
http://secunia.com/advisories/13191/