WORM_UTOTI.AB


 ALIASES:

Worm:Win32/Renocide.gen!A (Microsoft); Generic.dx!335DDC96143D (McAfee); W32.Harakit (Symantec); Worm.Win32.AutoIt.mm (Kaspersky); Trojan.Win32.AutoIt.gen.1 (v) (Sunbelt); Worm/Autoit.FHK (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.

It deletes itself after execution.

  TECHNICAL DETAILS

File Size:

511,948 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

20 Jun 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%\csrcs.exe

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

Autostart Technique

This worm modifies the following registry entries to ensure it automatic execution at every system startup:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows NT\CurrentVersion\Winlogon
Shell = "Explorer.exe csrcs.exe"

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

Other System Modifications

This worm adds the following registry keys:

HKEY_LOCAL_MACHINE\Software\Microsoft\
DRM\amty

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

It adds the following registry entries:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
DRM\amty
ilop = "1"

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

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

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
DRM\amty
fix1 = "1"

It modifies the following registry entries:

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Explorer\
Advanced
Hidden = "2"

(Note: The default value data of the said registry entry is 2.)

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

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Explorer\
Advanced\Folder\Hidden\
SHOWALL
CheckedValue = "1"

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

Dropping Routine

This worm drops the following files:

  • %User Temp%\aut1.tmp
  • %User Temp%\ljjzchk
  • %User Temp%\aut7.tmp
  • %User Temp%\eqrvlua

(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, or C:\Users\{user name}\AppData\Local\Temp on Windows Vista and 7.)

Other Details

This worm deletes itself after execution.

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

Identify and delete files detected as WORM_UTOTI.AB using either the Startup Disk or Recovery Console

[ 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\DRM
    • amty
  • 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_LOCAL_MACHINE\SOFTWARE\Microsoft\DRM\amty
    • ilop = "1"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\policies\Explorer\Run
    • csrcs = "%System%\csrcs.exe"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\Advanced
    • ShowSuperHidden = "0"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\DRM\amty
    • fix1 = "1"

Step 5

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_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\Advanced
    • From: Hidden = "2"
      To: Hidden = ""2""
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\Advanced
    • SuperHidden = "0"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Explorer\Advanced\Folder\Hidden\SHOWALL
    • From: CheckedValue = "1"
      To: CheckedValue = ""1""
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon
    • From: Shell = "Explorer.exe csrcs.exe"
      To: Shell = ""Explorer.exe""

Step 6

Search and delete these components

[ Learn More ]
There may be some components 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 Temp%\aut1.tmp
  • %User Temp%\ljjzchk
  • %User Temp%\aut7.tmp
  • %User Temp%\eqrvlua

Step 7

Scan your computer with your Trend Micro product to delete files detected as WORM_UTOTI.AB. 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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