Public Vulnerability Reports

BadBlue Unauthorized Proxy Vulnerability



BadBlue is a personal web server for Windows-based operating systems
that makes it simple for users to share multimedia and other files
over the internet.


Remote exploitation of a proxy vulnerability within BadBlue makes it
possible for an anonymous remote user to establish connections to any
port on any server through the BadBlue.

The file ext.dll is normally used for viewing files with URL's
containing "mfcisapicommand=loadpage", however it has a secondary
function as well.  This secondary function is called "PassThru", and can
be implemented within a URL in order to force the BadBlue server to act
as a proxy.  The following is an example of this:

http://[BadBlue Server]/ext.dll?mfcisapicommand=
PassThru&url=[Any IP:Any Port]/[Any Command]

It is important to note that BadBlue will translate any special
characters denoted by a % sign before sending it to the destination
server, which makes it possible to send spaces, carriage returns and
other special characters.


Though proxy capabilities pose no direct threat to the server running
BadBlue, an attacker could use the proxy to bypass firewalls in order
to enter internal networks. Successful exploitation could also give an
attacker the cover of anonymity when compromising other servers by using
BadBlue as a proxy.


iDEFENSE has confirmed the existence of this vulnerability against
BadBlue Personal Edition 2.5 and below. It is suspected that the
Enterprise Edition is vulnerable as well.


iDEFENSE is unaware of any workarounds for this issue.


A Mitre Corp. Common Vulnerabilities and Exposures (CVE) number has not
been assigned yet.


11/27/2002  Exploit acquired by iDEFENSE


Texonet is credited with this discovery.

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Copyright © 2004 Verisign, Inc.

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