TROJ_ZLOB.DSK
TrojanDownloader:Win32/Zlob.ALL (Microsoft); New Malware.as !! (McAfee); Trojan.Zlob (Symantec); Trojan-Downloader.Win32.Zlob.bcl (Kaspersky); Trojan.Win32.Generic!BT (Sunbelt); Trojan.Generic.2071185 (FSecure)
Windows 2000, Windows XP, Windows Server 2003
![](/vinfo/imgFiles/legend.jpg)
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
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%\DOCUME~1
- %System Root%\DOCUME~1\ADMINI~1
- %User Profile%\LOCALS~1
- %User Temp%\nst3.tmp
- %Program Files%\Image ActiveX Object
(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:\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.. %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.. %Program Files% is the default Program Files folder, usually C:\Program Files.)
Other System Modifications
This Trojan deletes the following files:
- %User Temp%\nsd1.tmp
- %User Temp%\nst3.tmp
(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.)
It adds the following registry keys:
HKEY_CURRENT_USER\Software\Internet Security
HKEY_CLASSES_ROOT\IAXObject.Chl\CLSID
HKEY_LOCAL_MACHINE\Software\Microsoft\
Windows\CurrentVersion\Uninstall\
Image ActiveX Object
It adds the following registry entries:
HKEY_CURRENT_USER\Software\Internet Security
Type = "4"
HKEY_CURRENT_USER\Software\Internet Security
Path = "%Program Files%\Image ActiveX Object"
HKEY_CURRENT_USER\Software\Internet Security
Removable = "0"
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Uninstall\
Image ActiveX Object
ProductionEnvironment = "1"
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Uninstall\
Image ActiveX Object
DisplayName = "Image ActiveX Object 2.0"
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Uninstall\
Image ActiveX Object
UninstallString = "%Program Files%\Image ActiveX Object\uninst.exe"
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Uninstall\
Image ActiveX Object
DisplayIcon = "%Program Files%\Image ActiveX Object\uninst.exe"
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Uninstall\
Image ActiveX Object
DisplayVersion = "2.0"
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Uninstall\
Image ActiveX Object
URLInfoAbout = "www.iaxobject.com"
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Uninstall\
Image ActiveX Object
Publisher = "Image ActiveX Object Software"
Dropping Routine
This Trojan drops the following files:
- %User Temp%\nsd2.tmp
- %User Temp%\nst3.tmp\reuninstall.ini
- %User Temp%\nst3.tmp\ioSpecial.ini
- %User Temp%\nst3.tmp\modern-wizard.bmp
- %User Temp%\nst3.tmp\modern-header.bmp
- %User Temp%\nst3.tmp\sxs.dll
- %Program Files%\Image ActiveX Object\uninst.exe
- %User Temp%\nst3.tmp\InstallOptions.dll
(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.. %Program Files% is the default Program Files folder, usually C:\Program Files.)
This report is generated via an automated analysis system.
SOLUTION
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
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\
- Internet Security
- In HKEY_CLASSES_ROOT\IAXObject.Chl
- CLSID
- In HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Uninstall
- Image ActiveX Object
Step 3
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\Internet Security
- Type = "4"
- In HKEY_CURRENT_USER\Software\Internet Security
- Path = "%Program Files%\Image ActiveX Object"
- In HKEY_CURRENT_USER\Software\Internet Security
- Removable = "0"
- In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Uninstall\Image ActiveX Object
- ProductionEnvironment = "1"
- In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Uninstall\Image ActiveX Object
- DisplayName = "Image ActiveX Object 2.0"
- In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Uninstall\Image ActiveX Object
- UninstallString = "%Program Files%\Image ActiveX Object\uninst.exe"
- In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Uninstall\Image ActiveX Object
- DisplayIcon = "%Program Files%\Image ActiveX Object\uninst.exe"
- In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Uninstall\Image ActiveX Object
- DisplayVersion = "2.0"
- In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Uninstall\Image ActiveX Object
- URLInfoAbout = "www.iaxobject.com"
- In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Uninstall\Image ActiveX Object
- Publisher = "Image ActiveX Object Software"
Step 4
Search and delete these files
- %User Temp%\nsd2.tmp
- %User Temp%\nst3.tmp\reuninstall.ini
- %User Temp%\nst3.tmp\ioSpecial.ini
- %User Temp%\nst3.tmp\modern-wizard.bmp
- %User Temp%\nst3.tmp\modern-header.bmp
- %User Temp%\nst3.tmp\sxs.dll
- %Program Files%\Image ActiveX Object\uninst.exe
- %User Temp%\nst3.tmp\InstallOptions.dll
Step 5
Search and delete these folders
- %System Root%\DOCUME~1
- %System Root%\DOCUME~1\ADMINI~1
- %User Profile%\LOCALS~1
- %User Temp%\nst3.tmp
- %Program Files%\Image ActiveX Object
Step 6
Scan your computer with your Trend Micro product to delete files detected as TROJ_ZLOB.DSK. 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 Temp%\nsd1.tmp
- %User Temp%\nst3.tmp
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