TSPY_LIMITAIL.AD
Infostealer.Limitail (Symantec), Mal/Cleaman-B (Sophos), Trojan-Spy.Zbot (Ikarus), a variant of MSIL/Injector.DCF trojan (Eset)
Windows 2000, Windows Server 2003, Windows XP (32-bit, 64-bit), Windows Vista (32-bit, 64-bit), Windows 7 (32-bit, 64-bit)
Threat Type: Spyware
Destructiveness: No
Encrypted:
In the wild: Yes
OVERVIEW
This spyware arrives as an attachment to email messages spammed by other malware/grayware or malicious users.
TECHNICAL DETAILS
565,824 bytes
EXE
Yes
13 Mar 2014
Arrival Details
This spyware arrives as an attachment to email messages spammed by other malware/grayware or malicious users.
Installation
This spyware drops the following files:
- %Application Data%\010112.txt
- %User Temp%\MSDCSC\rundll32.exe
(Note: %Application Data% is the current user's Application Data folder, which is usually C:\Documents and Settings\{user name}\Application Data on Windows 2000, XP, and Server 2003, or C:\Users\{user name}\AppData\Roaming on Windows Vista and 7.. %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.)
It creates the following folders:
- %User Temp%\MSDCSC
(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.)
Autostart Technique
This spyware adds the following registry entries to enable its automatic execution at every system startup:
HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
rundll32 = "%User Temp%\MSDCSC\rundll32.exe"
It modifies the following registry entries to ensure it automatic execution at every system startup:
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows NT\CurrentVersion\Winlogon
Userinit = "%System%\userinit.exe,%User Temp%\MSDCSC\rundll32.exe"
(Note: The default value data of the said registry entry is %System%\userinit.exe, .)
Other System Modifications
This spyware adds the following registry keys:
HKEY_CURRENT_USER\Software\DC3_FEXEC
SOLUTION
9.700
10.670.08
18 Mar 2014
10.671.00
18 Mar 2014
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 TSPY_LIMITAIL.AD using either the Startup Disk or Recovery Console
Step 3
Delete this registry key
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
- DC3_FEXEC
- DC3_FEXEC
Step 4
Delete this registry value
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
- rundll32 = "%User Temp%\MSDCSC\rundll32.exe"
- rundll32 = "%User Temp%\MSDCSC\rundll32.exe"
Step 5
Restore these modified registry values
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\Windows NT\CurrentVersion\Winlogon
- From: Userinit = "%System%\userinit.exe,%User Temp%\MSDCSC\rundll32.exe"
To: Userinit = %System%\userinit.exe,
- From: Userinit = "%System%\userinit.exe,%User Temp%\MSDCSC\rundll32.exe"
Step 6
Search and delete these folders
- %User Temp%\MSDCSC
Step 7
Search and delete this file
- %Application Data%\010112.txt
Step 8
Scan your computer with your Trend Micro product to delete files detected as TSPY_LIMITAIL.AD. 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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