TROJ_SISRON.WC
Trojan:Win32/Sisron!gmb(Microsoft); Trojan-Dropper.Win32.Dapato.rgq(Kaspersky); Win32/VB.QFN(ESET)
Windows
Threat Type: Trojan
Destructiveness: No
Encrypted: No
In the wild: Yes
OVERVIEW
Downloaded from the Internet
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 the initially executed copy of itself.
TECHNICAL DETAILS
159,744 bytes
EXE
No
20 Mar 2012
Connects to URLs/IPs
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 and executes them:
- %Application Data%\i6g8xs.exe
(Note: %Application Data% is the Application Data folder, where it usually is C:\Documents and Settings\{user name}\Application Data on Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\Users\{user name}\AppData\Roaming on Windows Vista (32- and 64-bit), Windows 7 (32- and 64-bit), Windows 8 (32- and 64-bit), Windows 8.1 (32- and 64-bit), Windows Server 2008, and Windows Server 2012.)
It drops the following files:
- %Application Data%\MouseDriver.bat
- %Application Data%\mdinstall.inf -->deleted afterwards
- %Application Data%\{8 random characters}.bat -->deleted afterwards
- %Application Data%\i6g8xs.log
(Note: %Application Data% is the Application Data folder, where it usually is C:\Documents and Settings\{user name}\Application Data on Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\Users\{user name}\AppData\Roaming on Windows Vista (32- and 64-bit), Windows 7 (32- and 64-bit), Windows 8 (32- and 64-bit), Windows 8.1 (32- and 64-bit), Windows Server 2008, and Windows Server 2012.)
It adds the following mutexes to ensure that only one of its copies runs at any one time:
- i6g8xs.exei6g8xs
Autostart Technique
This Trojan adds the following registry entries to enable its automatic execution at every system startup:
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Run
i6g8xs = "%Application Data%\i6g8xs.exe"
Other System Modifications
This Trojan modifies the following registry entries:
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Policies\
System
EnableLUA = "0"
(Note: The default value data of the said registry entry is 1.)
It also creates the following registry entry(ies) as part of its installation routine:
HKLM\SYSTEM\ControlSet001\
Services\MouseDriver\Security
Security = "{Hex Values}"
HKEY_LOCAL_MACHINE\SOFTWARE\tgs90gv74r
tgs90gv74rexepath = "%Application Data%\i6g8xs.exe"
HKEY_LOCAL_MACHINE\SOFTWARE\tgs90gv74r
tgs90gv74rpath = "%Application Data%"
It creates the following registry entry(ies) to bypass Windows Firewall:
HKLM\SYSTEM\ControlSet001\
Services\SharedAccess\Parameters\
FirewallPolicy\StandardProfile\AuthorizedApplications\
List
%Application Data%\i6g8xs.exe = "%Application Data%\i6g8xs.exe:*:Enabled:i6g8xs.exe"
HKLM\SYSTEM\ControlSet001\
Services\SharedAccess\Parameters\
FirewallPolicy\StandardProfile
DoNotAllowExceptions = "0"
(Note: The default value data of the said registry entry is "{User Defined}".)
Other Details
This Trojan connects to the following possibly malicious URL:
- w.{BLOCKED}discover.com
It deletes the initially executed copy of itself
NOTES:
This Trojan stops and disables the following security features at start up:
- WSCSVC (Windows Security Center Service)
- Windows Firewall/Internet Connection Sharing(ICS)
- Shared Access
SOLUTION
9.750
8.852.03
20 Mar 2012
8.853.00
21 Mar 2012
Step 1
Note that not all files, folders, and registry keys and entries are installed on your computer during this malware's/spyware's/grayware's execution. This may be due to incomplete installation or other operating system conditions. If you do not find the same files/folders/registry information, please proceed to the next step.
Step 2
Before doing any scans, Windows XP, Windows Vista, and Windows 7 users must disable System Restore to allow full scanning of their computers.
Step 3
Restart in Safe Mode
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_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
- i6g8xs = "%Application Data%\i6g8xs.exe"
- i6g8xs = "%Application Data%\i6g8xs.exe"
- In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\SharedAccess\Parameters\FirewallPolicy\StandardProfile\AuthorizedApplications\List
- %Application Data%\i6g8xs.exe = "%Application Data%\i6g8xs.exe:*:Enabled:i6g8xs.exe"
- %Application Data%\i6g8xs.exe = "%Application Data%\i6g8xs.exe:*:Enabled:i6g8xs.exe"
Step 5
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.
- HKEY_LOCAL_MACHINE\SOFTWARE\tgs90gv74r
- HKLM\SYSTEM\ControlSet001\Services\MouseDriver\Security
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_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\SharedAccess\Parameters\FirewallPolicy\StandardProfile
- From: DoNotAllowExceptions = "0"
To: DoNotAllowExceptions = {User Defined}
- From: DoNotAllowExceptions = "0"
- In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Policies\System
- From: EnableLUA = "0"
To: EnableLUA = 1
- From: EnableLUA = "0"
Step 7
Search and delete these files
- %Application Data%\i6g8xs.exe
- %Application Data%\MouseDriver.bat
- %Application Data%\mdinstall.inf
- %Application Data%\{8 random characters}.bat
- %Application Data%\i6g8xs.log
Step 8
Restart in normal mode and scan your computer with your Trend Micro product for files detected as TROJ_SISRON.WC. 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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