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Qbik WinGate Compressed Name Pointer DoS
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SUMMARY
<http://www.wingate.com/product-wingate.php> Qbik WinGate is an Internet
gateway and communications server. It includes functionality related to
efficiently sharing an Internet connection including DNS caching.
Remote exploitation of a denial of service vulnerability in Qbik IP
Management Limited's WinGate allows attackers to cause the application to
consume 100% of available CPU cycles.
DETAILS
Vulnerable Systems:
* Qbik Wingate version 6.1
* Earlier versions are suspected as well.
Sending a DNS request which contains a compressed name pointer which
references itself, will cause the vulnerable code to enter an infinite
loop which will consume all CPU cycles. The following packet illustrates
the DNS data that would be included in a packet triggering this
vulnerability:
\x00\x00 - Transaction ID
\x00\x00 - Flags
\x00\x01 - Questions
\x00\x00 - Answer RRs
\x00\x00 - Authority RRs
\x00\x00 - Additional RRs
\xc0\x0c - Query Name - Looping pointer
\x00\x00 - Query Type
\x00\x01 - Query Class
The DNS protocol allows for the compression of domain names in order to
reduce message sizes. This is accomplished by replacing an entire domain
name or a list of labels at the end of a domain name with a pointer to a
prior occurrence of the same name. The use of a pointer is indicated
within the Query Name field when the first two bits equal 1 (e.g. 0x0c).
The next byte is then interpreted as a pointer. In the packet detailed
above, the pointer itself is at the 12th byte within the DNS data portion
of the packet, thereby creating a looping pointer. The DNS compression
scheme is discussed in detail in <http://www.ietf.org/rfc/rfc1035.txt>
RFC 1035.
Successful exploitation of this vulnerability could prevent the WinGate
proxy from functioning and thereby deny legitimate users access to network
based resources. This vulnerability can be triggered by any user that is
able to send packets to the WinGate proxy. A single UDP packet is all that
is required and authentication credentials are not needed.
Vendor responce:
"Qbik acknowledges this to be a bug in WinGate version 6.1.4 and prior."
Qbik addressed this vulnerability within version 6.2.
CVE Information:
<http://www.cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2006-4518>
CVE-2006-4518
Disclosure Timeline:
* 08/17/2006 - Initial vendor notification
* 10/17/2006 - Initial vendor response
* 10/17/2006 - Second vendor notification
* 11/26/2006 - Coordinated public disclosure
ADDITIONAL INFORMATION
The information has been provided by iDefense.
The original article can be found at:
<http://labs.idefense.com/intelligence/vulnerabilities/display.php?id=444>
http://labs.idefense.com/intelligence/vulnerabilities/display.php?id=444
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