TSPY_DEXTER.CF
PWS:Win32/Dexter.A (Microsoft); PWSZbot-FTD!1205AD44C6B5 (McAfee); HEUR:Trojan.Win32.Generic (Kaspersky)
Windows 2000, Windows Server 2003, Windows XP (32-bit, 64-bit), Windows Vista (32-bit, 64-bit), Windows 7 (32-bit, 64-bit)
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
65,024 bytes
EXE
Yes
06 Aug 2014
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 drops the following copies of itself into the affected system:
- %User Profile%\Roaming\audiodg.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\Roaming
(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 spyware adds the following registry entries to enable its automatic execution at every system startup:
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Run
Conexant High Definition Audio Filter Agent = "%User Profile%\Roaming\audiodg.exe"
HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
Conexant High Definition Audio Filter Agent = "%User Profile%\Roaming\audiodg.exe"
Other System Modifications
This spyware deletes the following files:
- %System Root%\strokes.log
(Note: %System Root% is the root folder, which is usually C:\. It is also where the operating system is located.)
It adds the following registry keys:
HKEY_CURRENT_USER\Software\HelperSolutions Software
HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Policies\
Associations
It adds the following registry entries:
HKEY_CURRENT_USER\Software\HelperSolutions Software
Digit = "1f02a401-d298-4324-a3ef-8a24b25d966d"
HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Policies\
Associations
LowRiskFileTypes = ".exe;.bat;.reg;.vbs;"
HKEY_CURRENT_USER\Software\HelperSolutions Software
val1 = "%System Root%\strokes.log"
HKEY_CURRENT_USER\Software\HelperSolutions Software
val2 = "%System Root%\~tmp201402"
It modifies the following registry entries:
HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Internet Settings\
Zones\0
1806 = "0"
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Internet Settings\
Zones\0
1806 = "0"
Other Details
This spyware connects to the following possibly malicious URL:
- http://{BLOCKED}14.65
It deletes itself after execution.
This report is generated via an automated analysis system.
SOLUTION
9.700
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
- HelperSolutions Software
- In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Policies
- Associations
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
- Conexant High Definition Audio Filter Agent = "%User Profile%\Roaming\audiodg.exe"
- In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
- Conexant High Definition Audio Filter Agent = "%User Profile%\Roaming\audiodg.exe"
- In HKEY_CURRENT_USER\Software\HelperSolutions Software
- Digit = "1f02a401-d298-4324-a3ef-8a24b25d966d"
- In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Policies\Associations
- LowRiskFileTypes = ".exe;.bat;.reg;.vbs;"
- In HKEY_CURRENT_USER\Software\HelperSolutions Software
- val1 = "%System Root%\strokes.log"
- In HKEY_CURRENT_USER\Software\HelperSolutions Software
- val2 = "%System Root%\~tmp201402"
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_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Internet Settings\Zones\0
- 1806 = "0"
- In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Internet Settings\Zones\0
- 1806 = "0"
Step 6
Search and delete this folder
- %User Profile%\Application Data\Roaming
Step 7
Restart in normal mode and scan your computer with your Trend Micro product for files detected as TSPY_DEXTER.CF. 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 Root%\strokes.log
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