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TROJ_ZLOB.DWL

October 13, 2012
 ALIASES:

TrojanDropper:Win32/Alureon.gen, is password protected and cannot be scanned. (Microsoft); DNSChanger.pi (McAfee); Trojan.Zlob (Symantec); Backdoor.Win32.Small.fco (Kaspersky); Trojan.Win32.Generic!BT (Sunbelt); Trojan.Zlob.30133 (FSecure)

 PLATFORM:

Windows 2000, Windows XP, Windows Server 2003

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

  • 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

File Size:

210,521 bytes

File Type:

EXE

Memory Resident:

No

Initial Samples Received Date:

28 Jun 2012

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%\nsh3.tmp
  • %Program Files%\SelectiveAdmission
  • %System Root%\Documents and Settings\Administrator
  • %Start Menu%\Programs\SelectiveAdmission
  • %User Profile%\Application Data\WinRAR
  • %User Profile%\Application Data\VMware

(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.. %Start Menu% is the current user's Start Menu folder, which is usually C:\Windows\Profiles\{user name}\Start Menu on Windows 98 and ME, C:\WINNT\Profiles\{user name}\Start Menu on Windows NT and C:\Windows\Start Menu or C:\Documents and Settings\{User name}\Start Menu on Windows 2000, XP, and Server 2003.)

Other System Modifications

This Trojan deletes the following files:

  • %User Temp%\nsm1.tmp
  • %User Temp%\nsh3.tmp
  • %User Temp%\tmp2.exe
  • %Windows%\SoftwareDistribution\DataStore\Logs\edbtmp.log

(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.. %Windows% is the Windows folder, which is usually C:\Windows or C:\WINNT.)

It adds the following registry keys:

HKEY_CURRENT_USER\Software\SelectiveAdmission

HKEY_CLASSES_ROOT\SelectiveAdmission\CLSID

HKEY_LOCAL_MACHINE\Software\Microsoft\
Windows\CurrentVersion\Uninstall\
SelectiveAdmission

It adds the following registry entries:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Uninstall\
SelectiveAdmission
UninstallString = "%Program Files%\SelectiveAdmission\Uninstall.exe"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Uninstall\
SelectiveAdmission
InstallLocation = "%Program Files%\SelectiveAdmission"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Uninstall\
SelectiveAdmission
DisplayName = "SelectiveAdmission"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Uninstall\
SelectiveAdmission
DisplayIcon = "%Program Files%\SelectiveAdmission\Uninstall.exe,0"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Uninstall\
SelectiveAdmission
NoModify = "1"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Uninstall\
SelectiveAdmission
NoRepair = "1"

HKEY_CURRENT_USER\Software\SelectiveAdmission
Start Menu Folder = "SelectiveAdmission"

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\Tcpip\Parameters\
Interfaces\{0D50FF2A-9D59-41C1-A9AC-EB2C659D36FE}
NameServer = "85.255.115.110,85.255.112.175"

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\Tcpip\Parameters\
Interfaces\{0D50FF2A-9D59-41C1-A9AC-EB2C659D36FE}
DhcpNameServer = "85.255.115.110,85.255.112.175"

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\Tcpip\Parameters\
Interfaces\{6D128ACA-CE90-4D8D-B04F-CD01DBA59CE2}
NameServer = "85.255.115.110,85.255.112.175"

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\Tcpip\Parameters\
Interfaces\{6D128ACA-CE90-4D8D-B04F-CD01DBA59CE2}
DhcpNameServer = "85.255.115.110,85.255.112.175"

It modifies the following registry entries:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows NT\CurrentVersion\Winlogon
System = "kdylv.exe"

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\Tcpip\Parameters
DhcpNameServer = "85.255.115.110 85.255.112.175"

(Note: The default value data of the said registry entry is 192.168.239.2.)

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\Tcpip\Parameters
NameServer = "85.255.115.110 85.255.112.175"

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.)

Dropping Routine

This Trojan drops the following files:

  • %User Temp%\nsm2.tmp
  • %User Temp%\check.exe
  • %User Temp%\package.tmp
  • %User Temp%\nsh3.tmp\ExecDos.dll
  • %User Temp%\nsh3.tmp\modern-header.bmp
  • %Program Files%\SelectiveAdmission\Uninstall.exe
  • %Start Menu%\Programs\SelectiveAdmission\Uninstall.lnk
  • %User Temp%\nsh3.tmp\StartMenu.dll
  • tmp1.exe
  • tmp2.exe
  • %System%\kdylv.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.. %Program Files% is the default Program Files folder, usually C:\Program Files.. %Start Menu% is the current user's Start Menu folder, which is usually C:\Windows\Profiles\{user name}\Start Menu on Windows 98 and ME, C:\WINNT\Profiles\{user name}\Start Menu on Windows NT and C:\Windows\Start Menu or C:\Documents and Settings\{User name}\Start Menu on Windows 2000, XP, and Server 2003.. %System% is the Windows system folder, which is usually C:\Windows\System on Windows 98 and ME, C:\WINNT\System32 on Windows NT and 2000, or C:\Windows\System32 on Windows XP and Server 2003.)

This report is generated via an automated analysis system.

  SOLUTION

Minimum Scan Engine:

9.200

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

[ 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_CURRENT_USER\Software
    • SelectiveAdmission
  • In HKEY_CLASSES_ROOT\SelectiveAdmission
    • CLSID
  • In HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Uninstall
    • SelectiveAdmission

Step 3

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\Uninstall\SelectiveAdmission
    • UninstallString = "%Program Files%\SelectiveAdmission\Uninstall.exe"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Uninstall\SelectiveAdmission
    • InstallLocation = "%Program Files%\SelectiveAdmission"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Uninstall\SelectiveAdmission
    • DisplayName = "SelectiveAdmission"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Uninstall\SelectiveAdmission
    • DisplayIcon = "%Program Files%\SelectiveAdmission\Uninstall.exe,0"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Uninstall\SelectiveAdmission
    • NoModify = "1"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Uninstall\SelectiveAdmission
    • NoRepair = "1"
  • In HKEY_CURRENT_USER\Software\SelectiveAdmission
    • Start Menu Folder = "SelectiveAdmission"
  • In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\Tcpip\Parameters\Interfaces\{0D50FF2A-9D59-41C1-A9AC-EB2C659D36FE}
    • NameServer = "85.255.115.110,85.255.112.175"
  • In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\Tcpip\Parameters\Interfaces\{0D50FF2A-9D59-41C1-A9AC-EB2C659D36FE}
    • DhcpNameServer = "85.255.115.110,85.255.112.175"
  • In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\Tcpip\Parameters\Interfaces\{6D128ACA-CE90-4D8D-B04F-CD01DBA59CE2}
    • NameServer = "85.255.115.110,85.255.112.175"
  • In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\Tcpip\Parameters\Interfaces\{6D128ACA-CE90-4D8D-B04F-CD01DBA59CE2}
    • DhcpNameServer = "85.255.115.110,85.255.112.175"

Step 4

Restore this modified 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 NT\CurrentVersion\Winlogon
    • System = "kdylv.exe"
  • In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\Tcpip\Parameters
    • From: DhcpNameServer = "85.255.115.110 85.255.112.175"
      To: DhcpNameServer = ""192.168.239.2""
  • In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\Tcpip\Parameters
    • NameServer = "85.255.115.110 85.255.112.175"
  • In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\Eventlog\Application\ESENT
    • From: EventMessageFile = "%System%\ESENT.dll"
      To: EventMessageFile = ""{random values}""
  • In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\Eventlog\Application\ESENT
    • From: CategoryMessageFile = "%System%\ESENT.dll"
      To: CategoryMessageFile = ""{random values}""
  • In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\Eventlog\Application\ESENT
    • From: CategoryCount = "1"
      To: CategoryCount = ""10""
  • In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\Eventlog\Application\ESENT
    • From: TypesSupported = "7"
      To: TypesSupported = ""7""

Step 5

Search and delete these files

[ Learn More ]
There may be some component files 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%\nsm2.tmp
  • %User Temp%\check.exe
  • %User Temp%\package.tmp
  • %User Temp%\nsh3.tmp\ExecDos.dll
  • %User Temp%\nsh3.tmp\modern-header.bmp
  • %Program Files%\SelectiveAdmission\Uninstall.exe
  • %Start Menu%\Programs\SelectiveAdmission\Uninstall.lnk
  • %User Temp%\nsh3.tmp\StartMenu.dll
  • tmp1.exe
  • tmp2.exe
  • %System%\kdylv.exe

Step 6

Search and delete these folders

[ Learn More ]
Please make sure you check the Search Hidden Files and Folders checkbox in the More advanced options option to include all hidden folders in the search result.
  • %System Root%\DOCUME~1
  • %System Root%\DOCUME~1\ADMINI~1
  • %User Profile%\LOCALS~1
  • %User Temp%\nsh3.tmp
  • %Program Files%\SelectiveAdmission
  • %System Root%\Documents and Settings\Administrator
  • %Start Menu%\Programs\SelectiveAdmission
  • %User Profile%\Application Data\WinRAR
  • %User Profile%\Application Data\VMware

Step 7

Scan your computer with your Trend Micro product to delete files detected as TROJ_ZLOB.DWL. 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 8

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%\nsm1.tmp
  • %User Temp%\nsh3.tmp
  • %User Temp%\tmp2.exe
  • %Windows%\SoftwareDistribution\DataStore\Logs\edbtmp.log


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