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TROJ_FAM5c3.TOMA

December 22, 2012
 ALIASES:

PWS:Win32/Zbot.UO (Microsoft); Generic PWS.tc (McAfee); Infostealer.Banker.C (Symantec); Trojan-Spy.Win32.Zbot.soo (Kaspersky); Trojan.Crypt.Zcrypt (v) (Sunbelt); Trojan.Spy.ZBot.OP (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:

682,496 bytes

File Type:

EXE

Memory Resident:

No

Initial Samples Received Date:

03 Jan 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:

  • %System%\ntos.exe

(Note: %System% is the Windows system folder, which is usually C:\Windows\System32.)

It creates the following folders:

  • %System%\wsnpoem
  • %User Profile%\Application Data\wsnpoem

(Note: %System% is the Windows system folder, which is usually C:\Windows\System32.. %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.)

Other System Modifications

This Trojan deletes the following files:

  • %System%\ntos.exe

(Note: %System% is the Windows system folder, which is usually C:\Windows\System32.)

It adds the following registry keys:

HKEY_CURRENT_USER\software\microsoft\
windows\currentversion\explorer\
{43BF8CD1-C5D5-2230-7BB2-98F22C2B7DC6}

HKEY_CURRENT_USER\software\microsoft\
windows\currentversion\explorer\
{35106240-D2F0-DB35-716E-127EB80A0299}

HKEY_CURRENT_USER\software\microsoft\
windows\currentversion\explorer\
{19127AD2-394B-70F5-C650-B97867BAA1F7}

It adds the following registry entries:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows NT\CurrentVersion\Winlogon
userinit = "%System%\userinit.exe,%System%\ntos.exe,"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows NT\CurrentVersion\Network
UID = "BRIAN-EE28CA0B0_0000E05D"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Explorer\
{43BF8CD1-C5D5-2230-7BB2-98F22C2B7DC6}
{F710FA10-2031-3106-8872-93A2B5C5C620} = {random values}

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Explorer\
{43BF8CD1-C5D5-2230-7BB2-98F22C2B7DC6}
{E716FA10-2031-AA96-8E72-93A205C5C62C} = {random values}

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Explorer\
{35106240-D2F0-DB35-716E-127EB80A0299}
{F710FA10-2031-3106-8872-93A2B5C5C620} = {random values}

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Explorer\
{35106240-D2F0-DB35-716E-127EB80A0299}
{E716FA10-2031-AA96-8E72-93A205C5C62C} = {random values}

HKEY_CURRENT_USER\Software\Microsoft\
Windows NT\CurrentVersion\Network
UID = "BRIAN-EE28CA0B0_00011548"

HKEY_CURRENT_USER\Software\Microsoft\
Windows NT\CurrentVersion\Network
UID = "BRIAN-EE28CA0B0_00013E3C"

Other Details

This Trojan connects to the following possibly malicious URL:

  • http://{BLOCKED}t-step.net/f/cf46.bin

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

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\software\microsoft\windows\currentversion\explorer
    • {43BF8CD1-C5D5-2230-7BB2-98F22C2B7DC6}
  • In HKEY_CURRENT_USER\software\microsoft\windows\currentversion\explorer
    • {35106240-D2F0-DB35-716E-127EB80A0299}
  • In HKEY_CURRENT_USER\software\microsoft\windows\currentversion\explorer
    • {19127AD2-394B-70F5-C650-B97867BAA1F7}

Step 3

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 NT\CurrentVersion\Winlogon
    • userinit="%System%\userinit.exe,%System%\ntos.exe,"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Network
    • UID="BRIAN-EE28CA0B0_0000E05D"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\{43BF8CD1-C5D5-2230-7BB2-98F22C2B7DC6}
    • {F710FA10-2031-3106-8872-93A2B5C5C620}={random values}
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\{43BF8CD1-C5D5-2230-7BB2-98F22C2B7DC6}
    • {E716FA10-2031-AA96-8E72-93A205C5C62C}={random values}
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\{35106240-D2F0-DB35-716E-127EB80A0299}
    • {F710FA10-2031-3106-8872-93A2B5C5C620}={random values}
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\{35106240-D2F0-DB35-716E-127EB80A0299}
    • {E716FA10-2031-AA96-8E72-93A205C5C62C}={random values}
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows NT\CurrentVersion\Network
    • UID="BRIAN-EE28CA0B0_00011548"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows NT\CurrentVersion\Network
    • UID="BRIAN-EE28CA0B0_00013E3C"

Step 4

Search and delete these folders

[ Learn More ]
Please make sure you check the Search Hidden Files and Folders checkbox in the More advanced options option to include all hidden folders in the search result.
  • %System%\wsnpoem
  • %User Profile%\Application Data\wsnpoem

Step 5

Scan your computer with your Trend Micro product to delete files detected as TROJ_FAM5c3.TOMA. 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.

Step 6

Restore this file from backup only Microsoft-related files will be restored. If this malware/grayware also deleted files related to programs that are not from Microsoft, please reinstall those programs on you computer again. %System%\ntos.exe


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