WORM_SDBOT.DMJ

May 10, 2013
 ALIASES:

Worm:Win32/Mytobot.A (Microsoft); W32/Mytob.gen@MM (McAfee); W32.IRCBot.Gen (Symantec); Backdoor.Win32.SdBot.yr (Kaspersky); BehavesLike.Win32.Malware.ssc (mx-v) (Sunbelt); I-Worm/Mytob.JT (AVG)

 PLATFORM:

Windows 2000, Windows XP, Windows Server 2003

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

  • Threat Type: Worm

  • Destructiveness: No

  • Encrypted:

  • In the wild: Yes

  OVERVIEW

This worm 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:

34,816 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

10 May 2013

Arrival Details

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

  • %System%\rundllnt.exe

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

Autostart Technique

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

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Run
Microsoft Run The Dll Needing = "rundllnt.exe"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\RunServices
Microsoft Run The Dll Needing = "rundllnt.exe"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
Microsoft Run The Dll Needing = "rundllnt.exe"

Other System Modifications

This worm adds the following registry keys:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\RunServices

HKEY_CURRENT_USER\Software\Microsoft\
OLE

HKEY_CURRENT_USER\SYSTEM\CurrentCont

HKEY_LOCAL_MACHINE\SYSTEM\CurrentCont

It adds the following registry entries:

HKEY_CURRENT_USER\Software\Microsoft\
OLE
Microsoft Run The Dll Needing = "rundllnt.exe"

HKEY_CURRENT_USER\SYSTEM\CurrentCont
Microsoft Run The Dll Needing = "rundllnt.exe"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Ole
Microsoft Run The Dll Needing = "rundllnt.exe"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentCont
Microsoft Run The Dll Needing = "rundllnt.exe"

This report is generated via an automated analysis system.

  SOLUTION

Minimum Scan Engine:

9.300

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_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion
    • RunServices
  • In HKEY_CURRENT_USER\Software\Microsoft
    • OLE
  • In HKEY_CURRENT_USER\SYSTEM
    • CurrentCont
  • In HKEY_LOCAL_MACHINE\SYSTEM
    • CurrentCont

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
    • Microsoft Run The Dll Needing = "rundllnt.exe"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\RunServices
    • Microsoft Run The Dll Needing = "rundllnt.exe"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
    • Microsoft Run The Dll Needing = "rundllnt.exe"
  • In HKEY_CURRENT_USER\Software\Microsoft\OLE
    • Microsoft Run The Dll Needing = "rundllnt.exe"
  • In HKEY_CURRENT_USER\SYSTEM\CurrentCont
    • Microsoft Run The Dll Needing = "rundllnt.exe"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Ole
    • Microsoft Run The Dll Needing = "rundllnt.exe"
  • In HKEY_LOCAL_MACHINE\SYSTEM\CurrentCont
    • Microsoft Run The Dll Needing = "rundllnt.exe"

Step 5

Restart in normal mode and scan your computer with your Trend Micro product for files detected as WORM_SDBOT.DMJ. 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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