TSPY_FLYSTUD.BI
Worm:Win32/Nuj.A (Microsoft); [2.nsis]:BackDoor-DPR (McAfee); Trojan Horse (Symantec); ARC:NSIS, ARC:[1.exe]:Embedded, [1.exe/script.fly]:Trojan-Dropper.Win32.Flystud.ah, PAK:[1.exe/krnln (Kaspersky); BehavesLike.Win32.Malware.bsf (vs) (Sunbelt); Trojan:W32/Agent.DQRS (FSecure)
Windows 2000, Windows XP, Windows Server 2003
Threat Type: Spyware
Destructiveness: No
Encrypted:
In the wild: Yes
OVERVIEW
This spyware 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
Arrival Details
This spyware 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 spyware creates the following folders:
- %System Root%\DOCUME~1
- %System Root%\DOCUME~1\ADMINI~1
- %User Profile%\LOCALS~1
- %User Temp%\nsd2.tmp
- %User Temp%\E_4
(Note: %System Root% is the root folder, which is usually C:\. It is also where the operating system is located.. %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.. %User Temp% is the current user's Temp folder, which is usually C:\Documents and Settings\{user name}\Local Settings\Temp on Windows 2000, XP, and Server 2003, or C:\Users\{user name}\AppData\Local\Temp on Windows Vista and 7.)
Autostart Technique
This spyware registers as a system service to ensure its automatic execution at every system startup by adding the following registry keys:
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\Prstgressep\Parameters
Other System Modifications
This spyware deletes the following files:
- %User Temp%\nsx1.tmp
- %User Temp%\nsd2.tmp
(Note: %User Temp% is the current user's Temp folder, which is usually C:\Documents and Settings\{user name}\Local Settings\Temp on Windows 2000, XP, and Server 2003, or C:\Users\{user name}\AppData\Local\Temp on Windows Vista and 7.)
It adds the following registry entries:
HKEY_CURRENT_USER\Software
ifile = "{malware path and file name}%xy2.eif"
HKEY_CURRENT_USER\Software\Microsoft\
Internet Explorer\Main
Check_Associations = "NO"
HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\Prstgressep\Parameters
Application = "%System%\PrstService.exe"
Dropping Routine
This spyware drops the following files:
- %User Temp%\1.exe
- %User Temp%\xy2.eif
- %User Temp%\nsd2.tmp\System.dll
- %User Temp%\E_4\krnln.fnr
- %User Temp%\E_4\dp1.fne
- %User Temp%\E_4\Exmlrpc.fne
- %System Root%\delus.bat
- %System%\PrstService.dll
- %User Temp%\_EVLPK.tmp
- %Program Files%\Internet Explorer\IJL105.DLL
- eif
- %System%\PrstService.exe
- %Windows%\Fonts\PrstService.jpg
- %Program Files%\Internet Explorer\dp1.fne
- %Program Files%\Internet Explorer\Exmlrpc.fne
- %Program Files%\Internet Explorer\krnln.fnr
(Note: %User Temp% is the current user's Temp folder, which is usually C:\Documents and Settings\{user name}\Local Settings\Temp on Windows 2000, XP, and Server 2003, or C:\Users\{user name}\AppData\Local\Temp on Windows Vista and 7.. %System Root% is the root folder, which is usually C:\. It is also where the operating system is located.. %System% is the Windows system folder, which is usually C:\Windows\System32.. %Program Files% is the default Program Files folder, usually C:\Program Files in Windows 2000, Server 2003, and XP (32-bit), Vista (32-bit), and 7 (32-bit), or C:\Program Files (x86) in Windows XP (64-bit), Vista (64-bit), and 7 (64-bit).. %Windows% is the Windows folder, which is usually C:\Windows.)
Other Details
This spyware deletes itself after execution.
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
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\Prstgressep
- Parameters
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
- ifile = "{malware path and file name}%xy2.eif"
- In HKEY_CURRENT_USER\Software\Microsoft\Internet Explorer\Main
- Check_Associations = "NO"
- In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\Prstgressep\Parameters
- Application = "%System%\PrstService.exe"
Step 5
Search and delete these components
- %User Temp%\1.exe
- %User Temp%\xy2.eif
- %User Temp%\nsd2.tmp\System.dll
- %User Temp%\E_4\krnln.fnr
- %User Temp%\E_4\dp1.fne
- %User Temp%\E_4\Exmlrpc.fne
- %System Root%\delus.bat
- %System%\PrstService.dll
- %User Temp%\_EVLPK.tmp
- %Program Files%\Internet Explorer\IJL105.DLL
- eif
- %System%\PrstService.exe
- %Windows%\Fonts\PrstService.jpg
- %Program Files%\Internet Explorer\dp1.fne
- %Program Files%\Internet Explorer\Exmlrpc.fne
- %Program Files%\Internet Explorer\krnln.fnr
Step 6
Search and delete these folders
- %System Root%\DOCUME~1
- %System Root%\DOCUME~1\ADMINI~1
- %User Profile%\LOCALS~1
- %User Temp%\nsd2.tmp
- %User Temp%\E_4
Step 7
Restart in normal mode and scan your computer with your Trend Micro product for files detected as TSPY_FLYSTUD.BI. 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.
- %User Temp%\nsx1.tmp
- %User Temp%\nsd2.tmp
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