TROJ_AGENT.BAUC

October 13, 2012
 ALIASES:

Trojan:Win32/Agent (Microsoft); Generic Dropper!1rb (McAfee); Trojan.Gen (Symantec); Trojan-Dropper.Win32.Mudrop.rjr (Kaspersky); Trojan.Win32.Generic!SB.0 (Sunbelt)

 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:

596,204 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

19 Jul 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 creates the following folders:

  • %System Root%\Documents and Settings\Wilbert

(Note: %System Root% is the root folder, which is usually C:\. It is also where the operating system is located.)

Autostart Technique

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

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
xauyoid = "%User Profile%\xauyoid.exe /P"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
xauyoid = "%User Profile%\xauyoid.exe /C"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
xauyoid = "%User Profile%\xauyoid.exe /G"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
xauyoid = "%User Profile%\xauyoid.exe /H"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
xauyoid = "%User Profile%\xauyoid.exe /K"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
xauyoid = "%User Profile%\xauyoid.exe /t"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
xauyoid = "%User Profile%\xauyoid.exe /z"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
xauyoid = "%User Profile%\xauyoid.exe /x"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
xauyoid = "%User Profile%\xauyoid.exe /W"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
xauyoid = "%User Profile%\xauyoid.exe /m"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
xauyoid = "%User Profile%\xauyoid.exe /F"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
xauyoid = "%User Profile%\xauyoid.exe /M"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
xauyoid = "%User Profile%\xauyoid.exe /y"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
xauyoid = "%User Profile%\xauyoid.exe /J"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
xauyoid = "%User Profile%\xauyoid.exe /p"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
xauyoid = "%User Profile%\xauyoid.exe /f"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
xauyoid = "%User Profile%\xauyoid.exe /u"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
xauyoid = "%User Profile%\xauyoid.exe /L"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
xauyoid = "%User Profile%\xauyoid.exe /R"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
xauyoid = "%User Profile%\xauyoid.exe /O"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
xauyoid = "%User Profile%\xauyoid.exe /X"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
xauyoid = "%User Profile%\xauyoid.exe /B"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
xauyoid = "%User Profile%\xauyoid.exe /s"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
xauyoid = "%User Profile%\xauyoid.exe /n"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
xauyoid = "%User Profile%\xauyoid.exe /E"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
xauyoid = "%User Profile%\xauyoid.exe /v"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
xauyoid = "%User Profile%\xauyoid.exe /o"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
xauyoid = "%User Profile%\xauyoid.exe /S"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
xauyoid = "%User Profile%\xauyoid.exe /w"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
xauyoid = "%User Profile%\xauyoid.exe /e"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
xauyoid = "%User Profile%\xauyoid.exe /I"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
xauyoid = "%User Profile%\xauyoid.exe /d"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
xauyoid = "%User Profile%\xauyoid.exe /N"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
xauyoid = "%User Profile%\xauyoid.exe /c"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
xauyoid = "%User Profile%\xauyoid.exe /b"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
xauyoid = "%User Profile%\xauyoid.exe /q"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
xauyoid = "%User Profile%\xauyoid.exe /r"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
xauyoid = "%User Profile%\xauyoid.exe /j"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
xauyoid = "%User Profile%\xauyoid.exe /D"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
xauyoid = "%User Profile%\xauyoid.exe /T"

Other System Modifications

This Trojan deletes the following files:

  • %User Temp%\3.tmp
  • %User Profile%\QXFSVW~1.EXE

(Note: %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.. %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 adds the following registry keys:

HKEY_CURRENT_USER\Software\TZNLVCNDG

HKEY_LOCAL_MACHINE\Software\TZNLVCNDG

HKEY_LOCAL_MACHINE\Software\Microsoft\
Windows\CurrentVersion\Policies\
Explorer\Run

It adds the following registry entries:

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Explorer\
Advanced
ShowSuperHidden = "0"

HKEY_CURRENT_USER\Software\TZNLVCNDG
Cyryaed = "{random values}"

HKEY_LOCAL_MACHINE\SOFTWARE\TZNLVCNDG
Cyryaed = "{random values}"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\policies\
Explorer\Run
Gpgjg = "%System%\kbdfi19.exe"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Internet Settings
6 = "{random values}"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Internet Settings
6 = "{random values}"

Dropping Routine

This Trojan drops the following files:

  • %User Profile%\qxFSVWOcegcPUPu1.exe
  • %User Profile%\rot.exe
  • %User Profile%\sot.exe
  • %System%\kbdfi19.exe
  • %User Temp%\2.tmp

(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.. %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.. %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.)

Other Details

This Trojan connects to the following possibly malicious URL:

  • http://{BLOCKED}tfriendly.com/{random path}
  • http://{BLOCKED}ut4.cn/update/utu.dat

This report is generated via an automated analysis system.

  SOLUTION

Minimum Scan Engine:

9.200

Step 1

For Windows XP and Windows Server 2003 users, before doing any scans, please make sure you disable System Restore to allow full scanning of your computer.

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\Software
    • TZNLVCNDG
  • In HKEY_LOCAL_MACHINE\Software
    • TZNLVCNDG
  • In HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Policies\Explorer
    • Run

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_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
    • xauyoid = "%User Profile%\xauyoid.exe /P"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
    • xauyoid = "%User Profile%\xauyoid.exe /C"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
    • xauyoid = "%User Profile%\xauyoid.exe /G"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
    • xauyoid = "%User Profile%\xauyoid.exe /H"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
    • xauyoid = "%User Profile%\xauyoid.exe /K"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
    • xauyoid = "%User Profile%\xauyoid.exe /t"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
    • xauyoid = "%User Profile%\xauyoid.exe /z"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
    • xauyoid = "%User Profile%\xauyoid.exe /x"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
    • xauyoid = "%User Profile%\xauyoid.exe /W"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
    • xauyoid = "%User Profile%\xauyoid.exe /m"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
    • xauyoid = "%User Profile%\xauyoid.exe /F"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
    • xauyoid = "%User Profile%\xauyoid.exe /M"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
    • xauyoid = "%User Profile%\xauyoid.exe /y"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
    • xauyoid = "%User Profile%\xauyoid.exe /J"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
    • xauyoid = "%User Profile%\xauyoid.exe /p"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
    • xauyoid = "%User Profile%\xauyoid.exe /f"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
    • xauyoid = "%User Profile%\xauyoid.exe /u"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
    • xauyoid = "%User Profile%\xauyoid.exe /L"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
    • xauyoid = "%User Profile%\xauyoid.exe /R"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
    • xauyoid = "%User Profile%\xauyoid.exe /O"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
    • xauyoid = "%User Profile%\xauyoid.exe /X"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
    • xauyoid = "%User Profile%\xauyoid.exe /B"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
    • xauyoid = "%User Profile%\xauyoid.exe /s"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
    • xauyoid = "%User Profile%\xauyoid.exe /n"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
    • xauyoid = "%User Profile%\xauyoid.exe /E"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
    • xauyoid = "%User Profile%\xauyoid.exe /v"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
    • xauyoid = "%User Profile%\xauyoid.exe /o"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
    • xauyoid = "%User Profile%\xauyoid.exe /S"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
    • xauyoid = "%User Profile%\xauyoid.exe /w"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
    • xauyoid = "%User Profile%\xauyoid.exe /e"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
    • xauyoid = "%User Profile%\xauyoid.exe /I"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
    • xauyoid = "%User Profile%\xauyoid.exe /d"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
    • xauyoid = "%User Profile%\xauyoid.exe /N"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
    • xauyoid = "%User Profile%\xauyoid.exe /c"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
    • xauyoid = "%User Profile%\xauyoid.exe /b"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
    • xauyoid = "%User Profile%\xauyoid.exe /q"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
    • xauyoid = "%User Profile%\xauyoid.exe /r"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
    • xauyoid = "%User Profile%\xauyoid.exe /j"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
    • xauyoid = "%User Profile%\xauyoid.exe /D"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
    • xauyoid = "%User Profile%\xauyoid.exe /T"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\Advanced
    • ShowSuperHidden = "0"
  • In HKEY_CURRENT_USER\Software\TZNLVCNDG
    • Cyryaed = "{random values}"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\TZNLVCNDG
    • Cyryaed = "{random values}"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\policies\Explorer\Run
    • Gpgjg = "%System%\kbdfi19.exe"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Internet Settings
    • 6 = "{random values}"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Internet Settings
    • 6 = "{random values}"

Step 5

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%\qxFSVWOcegcPUPu1.exe
  • %User Profile%\rot.exe
  • %User Profile%\sot.exe
  • %System%\kbdfi19.exe
  • %User Temp%\2.tmp

Step 6

Search and delete this folder

[ 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 Root%\Documents and Settings\Wilbert

Step 7

Restart in normal mode and scan your computer with your Trend Micro product for files detected as TROJ_AGENT.BAUC. 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 8

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.

  • %User Temp%\3.tmp
  • %User Profile%\QXFSVW~1.EXE


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