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TROJ_ZBOT.SMUI

July 08, 2013
 ALIASES:

TrojanDownloader:Win32/Cred.B (Microsoft); Downloader.a!bkg (McAfee); Packed.Generic.360 (Symantec); Trojan-Downloader.Win32.Dapato.hgz (Kaspersky); Trojan-Downloader.Win32.Cred.b (v) (Sunbelt); Gen:Variant.Zbot.25 (FSecure)

 PLATFORM:

Windows 2000, Windows XP, Windows Server 2003

 OVERALL RISK RATING:
 DAMAGE POTENTIAL:
 DISTRIBUTION POTENTIAL:
 REPORTED INFECTION:

  • Threat Type: Trojan

  • Destructiveness: No

  • Encrypted:

  • In the wild: Yes

  OVERVIEW


This Trojan arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites.

  TECHNICAL DETAILS

File Size:

73,240 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

23 May 2012

Arrival Details

This Trojan arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites.

Installation

This Trojan drops the following copies of itself into the affected system:

  • %User Profile%\kbmac.exe
  • %User Profile%\Application Data\3gdxp.exe
  • %User Temp%\enrollcomp.exe

(Note: %User Profile% is the current user's profile folder, which is usually C:\Documents and Settings\{user name} on Windows 2000, XP, and Server 2003, or C:\Users\{user name} on Windows Vista and 7.. %User Temp% is the current user's Temp folder, which is usually C:\Documents and Settings\{user name}\Local Settings\Temp on Windows 2000, XP, and Server 2003, or C:\Users\{user name}\AppData\Local\Temp on Windows Vista and 7.)

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
kbmac = "%User Profile%\kbmac.exe"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
kbmac = "%User Profile%\kbmac.exe"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Run
3gdxp = "%User Profile%\Application Data\3gdxp.exe"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
3gdxp = "%User Profile%\Application Data\3gdxp.exe"

Other System Modifications

This Trojan adds the following registry keys:

HKEY_CURRENT_USER\???????????????????????

It adds the following registry entries:

HKEY_CURRENT_USER\???????????????????????
enrollcomp = "%User Temp%\enrollcomp.exe"

This report is generated via an automated analysis system.

  SOLUTION

Minimum Scan Engine:

9.200

Step 1

Before doing any scans, Windows XP, Windows Vista, and Windows 7 users must disable System Restore to allow full scanning of their computers.

Step 2

Restart in Safe Mode

[ Learn More ]

Step 3

Delete this registry key

[ Learn More ]

Important: Editing the Windows Registry incorrectly can lead to irreversible system malfunction. Please do this step only if you know how or you can ask assistance from your system administrator. Else, check this Microsoft article first before modifying your computer's registry.

  • In HKEY_CURRENT_USER
    • ???????????????????????

Step 4

Delete this registry value

[ Learn More ]

Important: Editing the Windows Registry incorrectly can lead to irreversible system malfunction. Please do this step only if you know how or you can ask assistance from your system administrator. Else, check this Microsoft article first before modifying your computer's registry.

  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
    • kbmac = "%User Profile%\kbmac.exe"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
    • kbmac = "%User Profile%\kbmac.exe"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
    • 3gdxp = "%User Profile%\Application Data\3gdxp.exe"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
    • 3gdxp = "%User Profile%\Application Data\3gdxp.exe"
  • In HKEY_CURRENT_USER\???????????????????????
    • enrollcomp = "%User Temp%\enrollcomp.exe"

Step 5

Restart in normal mode and scan your computer with your Trend Micro product for files detected as TROJ_ZBOT.SMUI. If the detected files have already been cleaned, deleted, or quarantined by your Trend Micro product, no further step is required. You may opt to simply delete the quarantined files. Please check this Knowledge Base page for more information.


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