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TROJ_LEMIR.CS

July 25, 2013
 ALIASES:

TrojanDownloader:Win32/Small.AUM (Microsoft); Generic MultiDropper.j (McAfee); Trojan.Dropper (Symantec); PAK:PECompact, Trojan.Win32.BKClient (Kaspersky); Trojan.Win32.BKClient (Sunbelt); Trojan.Generic.4789 (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:

49,876 bytes

File Type:

EXE

Memory Resident:

No

Initial Samples Received Date:

22 Oct 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:

  • %User Profile%\Microsoft\Address Book

(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.)

Other System Modifications

This Trojan deletes the following files:

  • %Windows%\Media\start.wav
  • %Windows%\Media\chord.wav

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

It adds the following registry keys:

HKEY_CURRENT_USER\SOFTWARE\Classes\
CLSID\{0BC9BC01-54D4-4CCE-2B7D-955164314CD4}\InProcServer32

HKEY_CURRENT_USER\Software\Microsoft\
Internet Explorer\Search

HKEY_CURRENT_USER\SOFTWARE\Classes\
CLSID\{0656A137-B161-CADD-9777-E37A75727E78}\InProcServer32

HKEY_LOCAL_MACHINE\SOFTWARE\Policies\
Microsoft\WindowsFirewall\DomainProfile

HKEY_LOCAL_MACHINE\SOFTWARE\Policies\
Microsoft\WindowsFirewall\StandardProfile

HKEY_CURRENT_USER\Software\Microsoft\
WAB\WAB4\Wab File Name

It adds the following registry entries:

HKEY_CURRENT_USER\CLSID\{0BC9BC01-54D4-4CCE-2B7D-955164314CD4}\
InProcServer32
ThreadingModel = "Apartment"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Explorer\
SharedTaskScheduler
{0BC9BC01-54D4-4CCE-2B7D-955164314CD4} = "OLE Module"

HKEY_CURRENT_USER\Software\Microsoft\
Internet Explorer\Main
Default_Search_URL = "http://www.{BLOCKED}-world.biz"

HKEY_CURRENT_USER\Software\Microsoft\
Internet Explorer
Search = "http://www.{BLOCKED}-world.biz"

HKEY_CURRENT_USER\Software\Microsoft\
Internet Explorer\Search
CustomizeSearch = "http://www.{BLOCKED}-world.biz"

HKEY_CURRENT_USER\Software\Microsoft\
Internet Explorer\Search
SearchAssistant = "http://www.{BLOCKED}-world.biz"

HKEY_CURRENT_USER\Software\Microsoft\
Internet Explorer
SearchURL = "http://www.{BLOCKED}-world.biz"

HKEY_CURRENT_USER\Software\Microsoft\
Internet Explorer\Main
Search Bar = "http://www.{BLOCKED}-world.biz"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Internet Explorer
Search = "http://www.LOX.com/index.html"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Internet Explorer
SearchURL = "http://www.LOX.com/index.html"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Internet Explorer\Main
Search Bar = "http://www.LOX.com/index.html"

HKEY_CURRENT_USER\CLSID\{0656A137-B161-CADD-9777-E37A75727E78}\
InProcServer32
ThreadingModel = "Apartment"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Explorer\
SharedTaskScheduler
{0656A137-B161-CADD-9777-E37A75727E78} = "OLE Module"

HKEY_CURRENT_USER\Software\Microsoft\
Internet Explorer\Main
Play_Background_Sounds = "no"

HKEY_CURRENT_USER\Software\Microsoft\
Internet Explorer\Main
Display Inline Videos = "no"

HKEY_CURRENT_USER\Software\Microsoft\
Internet Explorer\Security
id = "381508561458"

HKEY_CURRENT_USER\Software\Microsoft\
Internet Explorer\Security
rpt = "2599"

HKEY_CURRENT_USER\Software\Microsoft\
Internet Explorer\Security
dll = "0"

HKEY_LOCAL_MACHINE\SOFTWARE\Policies\
Microsoft\Windows\WindowsUpdate
DoNotAllowXPSP2 = "1"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\WindowsUpdate\
Auto Update
AUOptions = "1"

HKEY_LOCAL_MACHINE\SOFTWARE\Policies\
Microsoft\WindowsFirewall\DomainProfile
EnableFirewall = "0"

HKEY_LOCAL_MACHINE\SOFTWARE\Policies\
Microsoft\WindowsFirewall\StandardProfile
EnableFirewall = "0"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Internet Settings\
Zones
1001 = "1"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Internet Settings\
Zones
1001 = "1"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Internet Settings\
Zones
1004 = "1"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Internet Settings\
Zones
1004 = "1"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Internet Settings\
Zones
1200 = "0"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Internet Settings\
Zones
1200 = "0"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Internet Settings\
Zones
1809 = "3"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Internet Settings\
Zones
1809 = "3"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\SharedDlls
%Program Files%\Common Files\System\wab32.dll = "1"

HKEY_CURRENT_USER\Software\Microsoft\
WAB\WAB4
OlkContactRefresh = "0"

HKEY_CURRENT_USER\Software\Microsoft\
WAB\WAB4
OlkFolderRefresh = "0"

HKEY_CURRENT_USER\Identities\{8A24C031-62FE-4BF5-94F0-BFD4FBCD674B}
Identity Ordinal = "1"

It modifies the following registry entries:

HKEY_CURRENT_USER\Software\Microsoft\
Internet Explorer\Main
Search Page = "http://www.{BLOCKED}-world.biz"

(Note: The default value data of the said registry entry is http://www.microsoft.com/isapi/redir.dll?prd=ie&ar=iesearch.)

HKEY_CURRENT_USER\Software\Microsoft\
Internet Explorer\Main
Start Page = "http://www.{BLOCKED}-world.biz"

(Note: The default value data of the said registry entry is http://www.microsoft.com/isapi/redir.dll?prd=ie&pver=6&ar=msnhome.)

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Internet Explorer\Main
Search Page = "http://www.LOX.com/index.html"

(Note: The default value data of the said registry entry is http://www.microsoft.com/isapi/redir.dll?prd=ie&ar=iesearch.)

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Internet Explorer\Main
Default_Search_URL = "http://www.LOX.com/index.html"

(Note: The default value data of the said registry entry is http://www.microsoft.com/isapi/redir.dll?prd=ie&ar=iesearch.)

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Internet Explorer\Main
Start Page = "http://www.LOX.com/index.html"

(Note: The default value data of the said registry entry is http://www.microsoft.com/isapi/redir.dll?prd={SUB_PRD}&clcid={SUB_CLSID}&pver={SUB_PVER}&ar=home.)

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Internet Explorer\Search
CustomizeSearch = "http://www.LOX.com/index.html"

(Note: The default value data of the said registry entry is http://ie.search.msn.com/{SUB_RFC1766}/srchasst/srchcust.htm.)

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Internet Explorer\Search
SearchAssistant = "http://www.LOX.com/index.html"

(Note: The default value data of the said registry entry is http://ie.search.msn.com/{SUB_RFC1766}/srchasst/srchasst.htm.)

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Security Center
AntiVirusDisableNotify = "1"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Security Center
FirewallDisableNotify = "1"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Security Center
AntiVirusOverride = "1"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Security Center
FirewallOverride = "1"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Security Center
UpdatesDisableNotify = "1"

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\wscsvc
Start = "4"

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

HKEY_CURRENT_USER\Identities
Identity Ordinal = "2"

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

Dropping Routine

This Trojan drops the following files:

  • %System%\smart-search.exe
  • %System%\syst2.exe
  • %System%\syst3.exe
  • %System%\trf32.dll
  • %System%\mscnf.dll
  • %System%\thn32.dll
  • %System%\thn.dll
  • %User Profile%\Address Book\Wilbert.wab
  • %System Root%\mailz.txt

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

Other Details

This Trojan connects to the following possibly malicious URL:

  • http://{BLOCKED}c.org/report/ind.php?{random characters}
  • http://{BLOCKED}c.org/report/sox.php

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

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\Classes\CLSID\{0BC9BC01-54D4-4CCE-2B7D-955164314CD4}
    • InProcServer32
  • In HKEY_CURRENT_USER\Software\Microsoft\Internet Explorer
    • Search
  • In HKEY_CURRENT_USER\SOFTWARE\Classes\CLSID\{0656A137-B161-CADD-9777-E37A75727E78}
    • InProcServer32
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Microsoft\WindowsFirewall
    • DomainProfile
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Microsoft\WindowsFirewall
    • StandardProfile
  • In HKEY_CURRENT_USER\Software\Microsoft\WAB\WAB4
    • Wab File Name

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_CURRENT_USER\CLSID\{0BC9BC01-54D4-4CCE-2B7D-955164314CD4}\InProcServer32
    • ThreadingModel = "Apartment"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Explorer\SharedTaskScheduler
    • {0BC9BC01-54D4-4CCE-2B7D-955164314CD4} = "OLE Module"
  • In HKEY_CURRENT_USER\Software\Microsoft\Internet Explorer\Main
    • Default_Search_URL = "http://www.{BLOCKED}-world.biz"
  • In HKEY_CURRENT_USER\Software\Microsoft\Internet Explorer
    • Search = "http://www.{BLOCKED}-world.biz"
  • In HKEY_CURRENT_USER\Software\Microsoft\Internet Explorer\Search
    • CustomizeSearch = "http://www.{BLOCKED}-world.biz"
  • In HKEY_CURRENT_USER\Software\Microsoft\Internet Explorer\Search
    • SearchAssistant = "http://www.{BLOCKED}-world.biz"
  • In HKEY_CURRENT_USER\Software\Microsoft\Internet Explorer
    • SearchURL = "http://www.{BLOCKED}-world.biz"
  • In HKEY_CURRENT_USER\Software\Microsoft\Internet Explorer\Main
    • Search Bar = "http://www.{BLOCKED}-world.biz"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Internet Explorer
    • Search = "http://www.LOX.com/index.html"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Internet Explorer
    • SearchURL = "http://www.LOX.com/index.html"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Internet Explorer\Main
    • Search Bar = "http://www.LOX.com/index.html"
  • In HKEY_CURRENT_USER\CLSID\{0656A137-B161-CADD-9777-E37A75727E78}\InProcServer32
    • ThreadingModel = "Apartment"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Explorer\SharedTaskScheduler
    • {0656A137-B161-CADD-9777-E37A75727E78} = "OLE Module"
  • In HKEY_CURRENT_USER\Software\Microsoft\Internet Explorer\Main
    • Play_Background_Sounds = "no"
  • In HKEY_CURRENT_USER\Software\Microsoft\Internet Explorer\Main
    • Display Inline Videos = "no"
  • In HKEY_CURRENT_USER\Software\Microsoft\Internet Explorer\Security
    • id = "381508561458"
  • In HKEY_CURRENT_USER\Software\Microsoft\Internet Explorer\Security
    • rpt = "2599"
  • In HKEY_CURRENT_USER\Software\Microsoft\Internet Explorer\Security
    • dll = "0"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Microsoft\Windows\WindowsUpdate
    • DoNotAllowXPSP2 = "1"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\WindowsUpdate\Auto Update
    • AUOptions = "1"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Microsoft\WindowsFirewall\DomainProfile
    • EnableFirewall = "0"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Microsoft\WindowsFirewall\StandardProfile
    • EnableFirewall = "0"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Internet Settings\Zones
    • 1001 = "1"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Internet Settings\Zones
    • 1001 = "1"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Internet Settings\Zones
    • 1004 = "1"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Internet Settings\Zones
    • 1004 = "1"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Internet Settings\Zones
    • 1200 = "0"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Internet Settings\Zones
    • 1200 = "0"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Internet Settings\Zones
    • 1809 = "3"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Internet Settings\Zones
    • 1809 = "3"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\SharedDlls
    • %Program Files%\Common Files\System\wab32.dll = "1"
  • In HKEY_CURRENT_USER\Software\Microsoft\WAB\WAB4
    • OlkContactRefresh = "0"
  • In HKEY_CURRENT_USER\Software\Microsoft\WAB\WAB4
    • OlkFolderRefresh = "0"
  • In HKEY_CURRENT_USER\Identities\{8A24C031-62FE-4BF5-94F0-BFD4FBCD674B}
    • Identity Ordinal = "1"

Step 4

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\Internet Explorer\Main
    • From: Search Page = "http://www.{BLOCKED}-world.biz"
      To: Search Page = ""http://www.microsoft.com/isapi/redir.dll?prd=ie&ar=iesearch""
  • In HKEY_CURRENT_USER\Software\Microsoft\Internet Explorer\Main
    • From: Start Page = "http://www.{BLOCKED}-world.biz"
      To: Start Page = ""http://www.microsoft.com/isapi/redir.dll?prd=ie&pver=6&ar=msnhome""
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Internet Explorer\Main
    • From: Search Page = "http://www.LOX.com/index.html"
      To: Search Page = ""http://www.microsoft.com/isapi/redir.dll?prd=ie&ar=iesearch""
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Internet Explorer\Main
    • From: Default_Search_URL = "http://www.LOX.com/index.html"
      To: Default_Search_URL = ""http://www.microsoft.com/isapi/redir.dll?prd=ie&ar=iesearch""
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Internet Explorer\Main
    • From: Start Page = "http://www.LOX.com/index.html"
      To: Start Page = ""http://www.microsoft.com/isapi/redir.dll?prd={SUB_PRD}&clcid={SUB_CLSID}&pver={SUB_PVER}&ar=home""
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Internet Explorer\Search
    • From: CustomizeSearch = "http://www.LOX.com/index.html"
      To: CustomizeSearch = ""http://ie.search.msn.com/{SUB_RFC1766}/srchasst/srchcust.htm""
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Internet Explorer\Search
    • From: SearchAssistant = "http://www.LOX.com/index.html"
      To: SearchAssistant = ""http://ie.search.msn.com/{SUB_RFC1766}/srchasst/srchasst.htm""
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Security Center
    • AntiVirusDisableNotify = "1"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Security Center
    • FirewallDisableNotify = "1"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Security Center
    • AntiVirusOverride = "1"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Security Center
    • FirewallOverride = "1"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Security Center
    • UpdatesDisableNotify = "1"
  • In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\wscsvc
    • From: Start = "4"
      To: Start = ""2""
  • In HKEY_CURRENT_USER\Identities
    • From: Identity Ordinal = "2"
      To: Identity Ordinal = ""1""

Step 5

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.
  • %System%\smart-search.exe
  • %System%\syst2.exe
  • %System%\syst3.exe
  • %System%\trf32.dll
  • %System%\mscnf.dll
  • %System%\thn32.dll
  • %System%\thn.dll
  • %User Profile%\Address Book\Wilbert.wab
  • %System Root%\mailz.txt

Step 6

Search and delete this folder

[ 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.
  • %User Profile%\Microsoft\Address Book

Step 7

Scan your computer with your Trend Micro product to delete files detected as TROJ_LEMIR.CS. 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.

  • %Windows%\Media\start.wav
  • %Windows%\Media\chord.wav


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