Backdoor Lecna Exploits MS hcp URL XSS Vulnerability

July 1, 2010

SonicWALL UTM Research received reports of malware actively exploiting the recently reported vulnerability in Windows Help and Support Center (CVE-2010-1885) - MS hcp-URL Cross Site Scripting (June 10, 2010)

The malware author used the code below to exploit the vulnerability:


Upon successful exploitation, it downloads a component JavaScript file shown below as its payload:

    screenshot This file is being blocked by SonicWALL as GAV: JS.HCP.SVR.XSS (Exploit)

This script then downloads and executes the Backdoor Lecna file which uses an Adobe Acrobat icon to disguise itself as a acrobat file.


Malware Installation

Mutex Name:
To ensure that only one instance of this malware is running on the infected system it creates a mutex:

  • MicrosoftForZR

Files Added:
It drops a copy in Startup folder which allows itself to run on every system startup.

  • (Documents and Settings)All UsersStart MenuProgramsStartupAdobe Acrobat Speed Launcher.exe - GAV: Lecna.GEN (Trojan)

Registries Added:
It writes into the registry the host id which marks systems it successfully infected:

    Value: hostid
    Data: dword:000045f2

Files Downloaded:
It downloads the following files which are actually executable.

  • www.{REMOVED}.com/ForZRMail/myapp.htm - GAV: Lecna.GEN (Trojan)
  • www.{REMOVED}.com/ForZRMail/zr.txt - GAV: Lecna.GEN_2 (Trojan)

Network Activity:
Tries to connect to the following:

  • www.vic{REMOVED}.com
  • www.ian{REMOVED}.com

SonicWALL Gateway AntiVirus provided protection against this malicious backdoor via following signatures:

  • GAV: HCP.SVR.XSS.1 (Exploit)
  • GAV: JS.HCP.SVR.XSS (Exploit)
  • GAV: Lecna.GEN (Trojan)
  • GAV: Lecna.GEN_2 (Trojan)