TippingPoint Zero Day Initiative

Realnetworks Helix Server NTLM Authentication Invalid Base64 Remote Code Execution Vulnerability

ZDI-10-079: April 28th, 2010


CVSS Score

Affected Vendors

Affected Products

TippingPoint™ IPS Customer Protection

TippingPoint IPS customers are protected against this vulnerability by Digital Vaccine protection filter ID 6378. For further product information on the TippingPoint IPS:

Vulnerability Details

This vulnerability allows remote attackers to execute arbitrary code on vulnerable installations of RealNetworks Helix Server. Authentication is not required to exploit this vulnerability.

The specific flaw exists within the authentication provided by the administrative web interface and is only present if it is configured to use NTLM. The vulnerability can be triggered by specifying invalid Base64 string within the Authorization header. If the string is not proper Base64 the vulnerable function returns -1 which is not verified and is later used as a length to a string copy routine.

Vendor Response

RealNetworks states:

This issue has been addressed in v14:


Disclosure Timeline

    2009-07-14 - Vulnerability reported to vendor
    2010-04-28 - Coordinated public release of advisory


This vulnerability was discovered by: