TROJ_CRYPT.SMO


 ALIASES:

PWS:Win32/Zbot (Microsoft); PWS-Zbot.gen.gb (McAfee); Infostealer (Symantec); Trojan-Spy.Win32.Zbot.blqt (Kaspersky); Trojan.Win32.Generic!BT (Sunbelt); Trojan.Generic.5903510 (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:

  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:

164,864 bytes

File Type:

EXE

Initial Samples Received Date:

01 Oct 2011

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 creates the following folders:

  • %User Profile%\Entad
  • %User Profile%\Uqri
  • %User Profile%\Omyvx
  • %User Profile%\Microsoft\Dr Watson

(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.)

Other System Modifications

This Trojan adds the following registry keys:

HKEY_CURRENT_USER\Software\Microsoft\
Gohy

HKEY_CURRENT_USER\Software\Microsoft\
Internet Explorer\Privacy

It adds the following registry entries:

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
{4640CC0A-84AB-A9B0-094C-7ACD23C63CB5} = ""%User Profile%\Entad\gabao.exe""

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
{4640CC0A-84AB-A9B0-094C-7ACD23C63CB5} = ""%User Profile%\Entad\gabao.exe""

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
{4640CC0A-84AB-A9B0-094C-7ACD23C63CB5} = ""%User Profile%\Entad\gabao.exe""

It modifies the following registry entries:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
DrWatson
NumberOfCrashes = 1

(Note: The default value data of the said registry entry is 0.)

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
DrWatson
NumberOfCrashes = 2

(Note: The default value data of the said registry entry is 0.)

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
DrWatson
NumberOfCrashes = 3

(Note: The default value data of the said registry entry is 0.)

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows NT\CurrentVersion\Tracing\
Microsoft\Imapi
LogSessionName = "stdout"

(Note: The default value data of the said registry entry is stdout.)

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows NT\CurrentVersion\Tracing\
Microsoft\Imapi
Active = 1

(Note: The default value data of the said registry entry is 1.)

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows NT\CurrentVersion\Tracing\
Microsoft\Imapi
ControlFlags = 1

(Note: The default value data of the said registry entry is 1.)

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows NT\CurrentVersion\Tracing\
Microsoft\Imapi\ImapiSvc
Guid = "8107d8e9-e323-49f5-bba2-abc35c243dca"

(Note: The default value data of the said registry entry is 8107d8e9-e323-49f5-bba2-abc35c243dca.)

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows NT\CurrentVersion\Tracing\
Microsoft\Imapi\ImapiSvc
BitNames = " ImapiDebugError ImapiDebugWarning ImapiDebugTrace ImapiDebugInfo ImapiDebugX ImapiDebugSort"

(Note: The default value data of the said registry entry is ImapiDebugError ImapiDebugWarning ImapiDebugTrace ImapiDebugInfo ImapiDebugX ImapiDebugSort.)

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
DrWatson
NumberOfCrashes = 4

(Note: The default value data of the said registry entry is 0.)

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
DrWatson
NumberOfCrashes = 5

(Note: The default value data of the said registry entry is 0.)

It deletes the following registry keys:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
PCHealth\ErrorReporting\DW

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
PCHealth\ErrorReporting\DW

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
PCHealth\ErrorReporting\DW

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
PCHealth\ErrorReporting\DW

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
PCHealth\ErrorReporting\DW

Dropping Routine

This Trojan drops the following files:

  • %User Profile%\Entad\gabao.exe
  • %User Profile%\Uqri\voxim.ewe
  • %User Profile%\Omyvx\gouks.azq
  • %User Profile%\Dr Watson\drwtsn32.log
  • %User Profile%\Dr Watson\user.dmp
  • %Temp%\zlfp4zwx.TMP

(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.. %Temp% is the Windows Temporary folder, which is usually C:\Windows\Temp.)

Other Details

This Trojan connects to the following possibly malicious URL:

  • {BLOCKED}ax.jsp?v=4

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
    • Gohy
  • In HKEY_CURRENT_USER\Software\Microsoft\Internet Explorer
    • Privacy

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_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
    • {4640CC0A-84AB-A9B0-094C-7ACD23C63CB5}=""%User Profile%\Entad\gabao.exe""
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
    • {4640CC0A-84AB-A9B0-094C-7ACD23C63CB5}=""%User Profile%\Entad\gabao.exe""
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
    • {4640CC0A-84AB-A9B0-094C-7ACD23C63CB5}=""%User Profile%\Entad\gabao.exe""

Step 4

Restore these modified registry values

[ Learn More ]

Important:Editing the Windows Registry incorrectly can lead to irreversible system malfunction. Please do this only if you know how to or you can seek your system administrator's help. You may also check out this Microsoft article first before modifying your computer's registry.

  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\DrWatson
    • From: NumberOfCrashes=1
      To: NumberOfCrashes=0
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\DrWatson
    • From: NumberOfCrashes=2
      To: NumberOfCrashes=0
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\DrWatson
    • From: NumberOfCrashes=3
      To: NumberOfCrashes=0
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Tracing\Microsoft\Imapi
    • From: LogSessionName="stdout"
      To: LogSessionName=stdout
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Tracing\Microsoft\Imapi
    • From: Active=1
      To: Active=1
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Tracing\Microsoft\Imapi
    • From: ControlFlags=1
      To: ControlFlags=1
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Tracing\Microsoft\Imapi\ImapiSvc
    • From: Guid="8107d8e9-e323-49f5-bba2-abc35c243dca"
      To: Guid=8107d8e9-e323-49f5-bba2-abc35c243dca
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Tracing\Microsoft\Imapi\ImapiSvc
    • From: BitNames=" ImapiDebugError ImapiDebugWarning ImapiDebugTrace ImapiDebugInfo ImapiDebugX ImapiDebugSort"
      To: BitNames= ImapiDebugError ImapiDebugWarning ImapiDebugTrace ImapiDebugInfo ImapiDebugX ImapiDebugSort
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\DrWatson
    • From: NumberOfCrashes=4
      To: NumberOfCrashes=0
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\DrWatson
    • From: NumberOfCrashes=5
      To: NumberOfCrashes=0

Step 5

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.
  • %User Profile%\Entad
  • %User Profile%\Uqri
  • %User Profile%\Omyvx
  • %User Profile%\Microsoft\Dr Watson

Step 6

Search and delete these files

[ Learn More ]
There may be some component files that are hidden. Please make sure you check the Search Hidden Files and Folders checkbox in the More advanced options option to include all hidden files and folders in the search result.
  • %User Profile%\Entad\gabao.exe
  • %User Profile%\Uqri\voxim.ewe
  • %User Profile%\Omyvx\gouks.azq
  • %User Profile%\Dr Watson\drwtsn32.log
  • %User Profile%\Dr Watson\user.dmp
  • %Temp%\zlfp4zwx.TMP

Step 7

Scan your computer with your Trend Micro product to delete files detected as TROJ_CRYPT.SMO. 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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