TROJ_INJECTO.BHL
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.
It deletes itself after execution.
TECHNICAL DETAILS
46,836 bytes
EXE
Yes
20 Aug 2013
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 drops the following copies of itself into the affected system:
- %User Profile%\Application Data\csrss.exe
- %User Profile%\System32\rundll32.exe
- %User Profile%\System32\svchost.exe
(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 creates the following folders:
- %User Profile%\Application Data\System32
(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.)
Autostart Technique
This Trojan adds the following registry entries to enable its automatic execution at every system startup:
HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
Client Server Runtime Process = "%User Profile%\Application Data\csrss.exe"
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Run
Client Server Runtime Process = "%User Profile%\Application Data\csrss.exe"
HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
Host-process Windows (Rundll32.exe) = "%User Profile%\System32\rundll32.exe"
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Run
Host-process Windows (Rundll32.exe) = "%User Profile%\System32\rundll32.exe"
HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
Service Host Process for Windows = "%User Profile%\System32\svchost.exe"
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Run
Service Host Process for Windows = "%User Profile%\System32\svchost.exe"
HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
Host-process Windows (Rundll32.exe) = "%User Profile%\Application Data\csrss.exe"
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Run
Host-process Windows (Rundll32.exe) = "%User Profile%\Application Data\csrss.exe"
Other System Modifications
This Trojan adds the following registry keys:
HKEY_CURRENT_USER\SOFTWARE\BC Clients
It adds the following registry entries:
HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\SharedAccess\Parameters\
FirewallPolicy\StandardProfile\AuthorizedApplications\
List
Client Server Runtime Process = "%User Profile%\Application Data\csrss.exe"
HKEY_CURRENT_USER\Software\BC Clients
0 = ".{RM#'$H/::l -R+=8(.^]Y #7;Y]O9-;*L5'&aV(Y R*?3!:$6,"
HKEY_CURRENT_USER\Software\BC Clients
f = ""
HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\SharedAccess\Parameters\
FirewallPolicy\StandardProfile\AuthorizedApplications\
List
Host-process Windows (Rundll32.exe) = "%User Profile%\System32\rundll32.exe"
HKEY_CURRENT_USER\Software\BC Clients
1 = ".{RM#'$H/::l -R+=8(.^]Y #7;Y]O9-;*L5'&aV(Y RZ52&,@rU4-A-}{b$*,"
HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\SharedAccess\Parameters\
FirewallPolicy\StandardProfile\AuthorizedApplications\
List
Service Host Process for Windows = "%User Profile%\System32\svchost.exe"
HKEY_CURRENT_USER\Software\BC Clients
2 = ".{RM#'$H/::l -R+=8(.^]Y #7;Y]O9-;*L5'&aV(Y RZ52&,@rU?71!B2:g)97"
HKEY_CURRENT_USER\Software\BC Clients
d = "N{R{IDPO@xytBjM+Dz~y`KpO{IGVx/DyKJyjzpx"
HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\SharedAccess\Parameters\
FirewallPolicy\StandardProfile\AuthorizedApplications\
List
Host-process Windows (Rundll32.exe) = "%User Profile%\Application Data\csrss.exe"
HKEY_CURRENT_USER\Software\BC Clients
f = ""
HKEY_CURRENT_USER\Software\BC Clients
s = "qwg~rdgu`xtiD2&!.!=/+="
It modifies the following registry entries:
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Controls Folder\
PowerCfg
LastID = "5"
(Note: The default value data of the said registry entry is 5.)
Other Details
This Trojan deletes itself after execution.
This report is generated via an automated analysis system.
SOLUTION
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
Restart in Safe Mode
Step 3
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
- BC Clients
Step 4
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\Microsoft\Windows\CurrentVersion\Run
- Client Server Runtime Process = "%User Profile%\Application Data\csrss.exe"
- In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
- Client Server Runtime Process = "%User Profile%\Application Data\csrss.exe"
- In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
- Host-process Windows (Rundll32.exe) = "%User Profile%\System32\rundll32.exe"
- In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
- Host-process Windows (Rundll32.exe) = "%User Profile%\System32\rundll32.exe"
- In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
- Service Host Process for Windows = "%User Profile%\System32\svchost.exe"
- In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
- Service Host Process for Windows = "%User Profile%\System32\svchost.exe"
- In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
- Host-process Windows (Rundll32.exe) = "%User Profile%\Application Data\csrss.exe"
- In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
- Host-process Windows (Rundll32.exe) = "%User Profile%\Application Data\csrss.exe"
- In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\SharedAccess\Parameters\FirewallPolicy\StandardProfile\AuthorizedApplications\List
- Client Server Runtime Process = "%User Profile%\Application Data\csrss.exe"
- In HKEY_CURRENT_USER\Software\BC Clients
- 0 = ".{RM#'$H/::l -R+=8(.^]Y #7;Y]O9-;*L5'&aV(Y R*?3!:$6,"
- In HKEY_CURRENT_USER\Software\BC Clients
- f = ""
- In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\SharedAccess\Parameters\FirewallPolicy\StandardProfile\AuthorizedApplications\List
- Host-process Windows (Rundll32.exe) = "%User Profile%\System32\rundll32.exe"
- In HKEY_CURRENT_USER\Software\BC Clients
- 1 = ".{RM#'$H/::l -R+=8(.^]Y #7;Y]O9-;*L5'&aV(Y RZ52&,@rU4-A-}{b$*,"
- In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\SharedAccess\Parameters\FirewallPolicy\StandardProfile\AuthorizedApplications\List
- Service Host Process for Windows = "%User Profile%\System32\svchost.exe"
- In HKEY_CURRENT_USER\Software\BC Clients
- 2 = ".{RM#'$H/::l -R+=8(.^]Y #7;Y]O9-;*L5'&aV(Y RZ52&,@rU?71!B2:g)97"
- In HKEY_CURRENT_USER\Software\BC Clients
- d = "N{R{IDPO@xytBjM+Dz~y`KpO{IGVx/DyKJyjzpx"
- In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\SharedAccess\Parameters\FirewallPolicy\StandardProfile\AuthorizedApplications\List
- Host-process Windows (Rundll32.exe) = "%User Profile%\Application Data\csrss.exe"
- In HKEY_CURRENT_USER\Software\BC Clients
- f = ""
- In HKEY_CURRENT_USER\Software\BC Clients
- s = "qwg~rdgu`xtiD2&!.!=/+="
Step 5
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\SOFTWARE\Microsoft\Windows\CurrentVersion\Controls Folder\PowerCfg
- From: LastID = "5"
To: LastID = ""5""
- From: LastID = "5"
Step 6
Search and delete this folder
- %User Profile%\Application Data\System32
Step 7
Restart in normal mode and scan your computer with your Trend Micro product for files detected as TROJ_INJECTO.BHL. 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.
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