TROJ_FARFLI.XLS
Windows 2000, Windows XP, Windows Server 2003
Threat Type: Trojan
Destructiveness: No
Encrypted: Yes
In the wild: Yes
OVERVIEW
This Trojan arrives by being dropped by a specific malware. It modifies the affected system's registry in order to execute the malware it drops as a service.
This Trojan may be dropped by other malware.
It deletes itself after execution.
TECHNICAL DETAILS
65,024 bytes
EXE
Yes
21 May 2011
Drops files, Terminates processes
Arrival Details
This Trojan may be dropped by the following malware:
- TROJ_XDROP.XLS
Installation
This Trojan drops the following files:
- %System%\{Service name}ex.dll - BKDR_FARFLI.XLS
(Note: %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.)
Autostart Technique
This Trojan creates the following registry entries to enable automatic execution of dropped component at every system startup:
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\{found service name}
Type = "120"
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\{found service name}
Start = "2"
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\{found service name}
ErrorControl = "1"
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\{found service name}
DisplayName = "{found service name}"
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\{found service name}
Description = Manages audio devices for Windows-based programs. If this service is stopped, audio devices and effects will not function properly. If this service is disabled, any services that explicitly depend on it will fail to start.
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\{found service name}\Parameters
ServiceDll = "%System%\{malware filename}ex.dll"
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\{found service name}\Security
Security = "{hex values}"
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\{found service name}
ImagePath = "%System%\svchost.exe -k netsvcs"
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\{found service name}
ObjectName = "LocalSystem"
Process Termination
This Trojan terminates the following processes if found running in the affected system's memory:
- avp.exe
- SfCtlCom.exe
- ccsvchst.exe
Other Details
This Trojan deletes itself after execution.
NOTES:
It parses the following registry entry to determine Network Services names:
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Svchost netsvc
If the malware finds any Network Service that has no System Service, it will use the found name as file name for its dropped malware and the malware's service. By doing this, the dropped malware executes as a service every time the affected system is started.
SOLUTION
8.900
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
Remove malware files dropped/downloaded by TROJ_FARFLI.XLS
- TROJ_XDROP.XLS
- BKDR_FARFLI.XLS
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_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services
- {found service name}
- {found service name}
Step 4
Scan your computer with your Trend Micro product to delete files detected as TROJ_FARFLI.XLS. 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.
NOTES:
To identify the service name used by the malware, please scan your computer with your Trend Micro product and note the name of the file detected as BKDR_FARFLI.XLS.
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