TROJ_VUNDO

This description is based is a compiled analysis of several variants of TROJ_VUNDO. Note that specific data such as file names and registry values may vary for each variant.

This Trojan arrives as a file that exports the functions of other malware/grayware. It may arrive bundled with malware packages as a malware component. It may be unknowingly downloaded by a user while visiting malicious websites.

It registers itself as a Browser Helper Object (BHO) to ensure its automatic execution every time Internet Explorer is run. It does this by creating registry keys/entries.

It connects to certain websites to send and receive information. It requires its main component to successfully perform its intended routine. However, as of this writing, the said sites are inaccessible.

Arrival Details

This Trojan arrives as a file that exports the functions of other malware/grayware.

It may arrive bundled with malware packages as a malware component.

It may be unknowingly downloaded by a user while visiting malicious websites.

Installation

This Trojan drops the following files:

• %System%\{random name}.dll

(Note: %System% is the Windows system folder, which is usually C:\Windows\System on Windows 98 and ME, C:\WINNT\System32 on Windows NT and 2000, or C:\Windows\System32 on Windows XP and Server 2003.)

It drops the following copies of itself into the affected system:

• %User Profile%\Application Data\{random characters}.exe

(Note: %User Profile% is the current user's profile folder, which is usually C:\Windows\Profiles\{user name} on Windows 98 and ME, C:\WINNT\Profiles\{user name} on Windows NT, and C:\Documents and Settings\{user name} on Windows 2000, XP, and Server 2003.)

It injects itself into the following processes running in the affected system's memory:

• WINLOGON.EXE

Autostart Technique

This Trojan adds the following registry entries to enable its automatic execution at every system startup:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Run
{random string} = rundll32.exe "{malware path and file name}"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows NT\CurrentVersion\Winlogon\
Notify\{Malware file name without extension}
DLLName = "{Malware file name}"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows NT\CurrentVersion\Windows
AppInit_DLLs = "{Malware path and file name}"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Explorer\
ShellExecuteHooks
{Malware CLSID} = ""

It registers itself as a Browser Helper Object (BHO) to ensure its automatic execution every time Internet Explorer is run. It does this by creating the following registry key(s)/entry(ies):

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
CLSID\{Random CLSID}\InprocServer32
(Default) = "{Malware path and file name}"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Explorer\
Browser Helper Objects\{Random CLSID}

Download Routine

This Trojan connects to the following URL(s) to download its component file(s):

• www.{BLOCKED}te.10dig.net
• {BLOCKED}lmall.8866.org
• {BLOCKED}er.{BLOCKED}ts.org
• {BLOCKED}ns.{BLOCKED}8.net
• {BLOCKED}ercenter.vicp.cc

Other Details

This Trojan connects to the following possibly malicious URL:

• http://{BLOCKED}0.{BLOCKED}0.138.67/ym/Attachments?YY={random characters}
• jmlc.{BLOCKED}p3.com:53

It connects to the following website to send and receive information:

• http://{BLOCKED}.103.60/go//?cmp=vmtek_update&lid=run&uid={data}&guid={data}

It requires its main component to successfully perform its intended routine.

However, as of this writing, the said sites are inaccessible.

NOTES:

This description is based is a compiled analysis of several variants of TROJ_VUNDO. Note that specific data such as file names and registry values may vary for each variant.