WORM_AUTORUN.ZAI
Windows 2000, Windows XP, Windows Server 2003
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
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 creates the following folders:
- %System Root%\Documents and Settings\Wilbert
- %User Profile%\r23R45eS
(Note: %System Root% is the root folder, which is usually C:\. It is also where the operating system is located.. %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 worm deletes the following files:
- %User Profile%\f79P74iZ.YG5
(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.)
It adds the following registry keys:
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
ESENT\Process\RegSvcs
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
ESENT\Process\RegSvcs\
DEBUG
It modifies the following registry entries:
HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\Eventlog\Application\
ESENT
EventMessageFile = "%System%\ESENT.dll"
(Note: The default value data of the said registry entry is {random values}.)
HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\Eventlog\Application\
ESENT
CategoryMessageFile = "%System%\ESENT.dll"
(Note: The default value data of the said registry entry is {random values}.)
HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\Eventlog\Application\
ESENT
CategoryCount = "1"
(Note: The default value data of the said registry entry is 10.)
HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\Eventlog\Application\
ESENT
TypesSupported = "7"
(Note: The default value data of the said registry entry is 7.)
HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Explorer\
Advanced
Hidden = "1"
(Note: The default value data of the said registry entry is 2.)
Dropping Routine
This worm drops the following files:
- __tmp_rar_sfx_access_check_711937
- scvhos.exe
- vZe.rke
- %User Temp%\aut6.tmp
- %User Profile%\Application Data\pid.txt
- %User Profile%\Application Data\pidloc.txt
- %User Temp%\holderwb.txt
- %User Profile%\f79P74iZ.YG5
- %System Root%\scvhos.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, or C:\Users\{user name}\AppData\Local\Temp on Windows Vista and 7.. %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.. %System Root% is the root folder, which is usually C:\. It is also where the operating system is located.)
This report is generated via an automated analysis system.
SOLUTION
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
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\ESENT\Process
- RegSvcs
- In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\ESENT\Process\RegSvcs
- DEBUG
Step 3
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\SYSTEM\ControlSet001\Services\Eventlog\Application\ESENT
- From: EventMessageFile = "%System%\ESENT.dll"
To: EventMessageFile = ""{random values}""
- From: EventMessageFile = "%System%\ESENT.dll"
- In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\Eventlog\Application\ESENT
- From: CategoryMessageFile = "%System%\ESENT.dll"
To: CategoryMessageFile = ""{random values}""
- From: CategoryMessageFile = "%System%\ESENT.dll"
- In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\Eventlog\Application\ESENT
- From: CategoryCount = "1"
To: CategoryCount = ""10""
- From: CategoryCount = "1"
- In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\Eventlog\Application\ESENT
- From: TypesSupported = "7"
To: TypesSupported = ""7""
- From: TypesSupported = "7"
- In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\Advanced
- From: Hidden = "1"
To: Hidden = ""2""
- From: Hidden = "1"
Step 4
Search and delete these components
- __tmp_rar_sfx_access_check_711937
- scvhos.exe
- vZe.rke
- %User Temp%\aut6.tmp
- %User Profile%\Application Data\pid.txt
- %User Profile%\Application Data\pidloc.txt
- %User Temp%\holderwb.txt
- %User Profile%\f79P74iZ.YG5
- %System Root%\scvhos.exe
Step 5
Search and delete these folders
- %System Root%\Documents and Settings\Wilbert
- %User Profile%\r23R45eS
Step 6
Scan your computer with your Trend Micro product to delete files detected as WORM_AUTORUN.ZAI. 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 7
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 Profile%\f79P74iZ.YG5
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