BKDR_MOSUCK.A
Backdoor:Win32/Mosucker.0_7 (Microsoft); BackDoor-EE.gen (McAfee); Backdoor.Mosuck (Symantec); Backdoor.Win32.MoSucker.dd, Backdoor.Win32.MoSucker.dd (Kaspersky); Trojan.Generic.7827763 (FSecure)
Windows 2000, Windows XP, Windows Server 2003
![](/vinfo/imgFiles/legend.jpg)
Threat Type: Backdoor
Destructiveness: No
Encrypted:
In the wild: Yes
OVERVIEW
This backdoor arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites.
It disables Task Manager, Registry Editor, and Folder Options.
TECHNICAL DETAILS
Arrival Details
This backdoor arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites.
Autostart Technique
This backdoor adds the following registry entries to enable its automatic execution at every system startup:
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Run
{%%#%#%##-%###-%%#%-%#%#-%%#%####%%%#} = "%Windows%\Fonts\lsass.exe"
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\RunOnce
{%%#%#%##-%###-%%#%-%#%#-%%#%####%%%#} = "%Windows%\Fonts\lsass.exe /RunOnce"
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\RunOnceEx
{%%#%#%##-%###-%%#%-%#%#-%%#%####%%%#} = "%Windows%\Fonts\lsass.exe"
Other System Modifications
This backdoor deletes the following files:
- %System%\drivers\etc\hosts
(Note: %System% is the Windows system folder, which is usually C:\Windows\System32.)
It adds the following registry keys:
HKEY_CURRENT_USER\Software\VB and VBA Program Settings\
Options\Windows XP
HKEY_CURRENT_USER\Software\VB and VBA Program Settings\
HROSWXC14302010000JQSRI\HROSWXC14302010000JQSRI
HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Policies\
System
It adds the following registry entries:
HKEY_CURRENT_USER\Software\VB and VBA Program Settings\
Options\Windows XP
1 = "{random characters}"
HKEY_CURRENT_USER\Software\VB and VBA Program Settings\
HROSWXC14302010000JQSRI\HROSWXC14302010000JQSRI
# = "£§???v??¬Î²¼¨¾Îƾ¿Å½Á »Ê´?Ë~¼Á³"
HKEY_CURRENT_USER\Software\VB and VBA Program Settings\
HROSWXC14302010000JQSRI\HROSWXC14302010000JQSRI
1 = "???£¢vQ??z}v??@????y?w£m"
HKEY_CURRENT_USER\Software\VB and VBA Program Settings\
HROSWXC14302010000JQSRI\HROSWXC14302010000JQSRI
2 = "???¤v??¬??w???P???y???S???????Y????~w???f??¶ªªµ¸¹Q¹?¼°y¹?R?u??Yµ?°"
HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Explorer\
Advanced
ShowSuperHidden = "1"
It modifies the following registry entries:
HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Explorer\
Advanced
Hidden = "1"
(Note: The default value data of the said registry entry is 2.)
It creates the following registry entry(ies) to disable Task Manager, Registry Tools and Folder Options:
HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Policies\
System
DisableRegistryTools = "1"
HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Policies\
System
DisableTaskmgr = "1"
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
Restart in Safe Mode
Step 3
Enable Registry Editor, Task Manager, and Folder options
Step 4
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\VB and VBA Program Settings\Options
- Windows XP
- In HKEY_CURRENT_USER\Software\VB and VBA Program Settings
- HROSWXC14302010000JQSRI
- In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Policies
- System
Step 5
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_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
- {%%#%#%##-%###-%%#%-%#%#-%%#%####%%%#} = "%Windows%\Fonts\lsass.exe"
- In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\RunOnce
- {%%#%#%##-%###-%%#%-%#%#-%%#%####%%%#} = "%Windows%\Fonts\lsass.exe /RunOnce"
- In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\RunOnceEx
- {%%#%#%##-%###-%%#%-%#%#-%%#%####%%%#} = "%Windows%\Fonts\lsass.exe"
- In HKEY_CURRENT_USER\Software\VB and VBA Program Settings\Options\Windows XP
- 1 = "{random characters}"
- In HKEY_CURRENT_USER\Software\VB and VBA Program Settings\HROSWXC14302010000JQSRI\HROSWXC14302010000JQSRI
- # = "£§???v??¬Î²¼¨¾Îƾ¿Å½Á »Ê´?Ë~¼Á³"
- In HKEY_CURRENT_USER\Software\VB and VBA Program Settings\HROSWXC14302010000JQSRI\HROSWXC14302010000JQSRI
- 1 = "???£¢vQ??z}v??@????y?w£m"
- In HKEY_CURRENT_USER\Software\VB and VBA Program Settings\HROSWXC14302010000JQSRI\HROSWXC14302010000JQSRI
- 2 = "???¤v??¬??w???P???y???S???????Y????~w???f??¶ªªµ¸¹Q¹?¼°y¹?R?u??Yµ?°"
- In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\Advanced
- ShowSuperHidden = "1"
Step 6
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_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\Advanced
- From: Hidden = "1"
To: Hidden = ""2""
- From: Hidden = "1"
Step 7
Restart in normal mode and scan your computer with your Trend Micro product for files detected as BKDR_MOSUCK.A. 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.
- %System%\drivers\etc\hosts
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