TROJ_PHASE.A
Trojan.Phase (Symantec); Win32:PhaseBot-A [Trj] (Avast); a variant of Win32/Phase.A (ESET);
Windows 7
Threat Type: Trojan
Destructiveness: No
Encrypted: Yes
In the wild: Yes
OVERVIEW
This Trojan retrieves specific information from the affected system.
TECHNICAL DETAILS
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
Windows Host Process (RunDll) = "rundll32.exe javascript:"\..\mshtml,RunHTMLApplication ";eval((new%20ActiveXObject("WScript.Shell")).RegRead("HKCU\Software\Microsoft\Active%20Setup\Installed%20Components\{unique bot GUID}\JavaScript"));close();;"
Other System Modifications
This Trojan adds the following registry keys:
HKEY_CURRENT_USER\SOFTWARE\Microsoft\
Active Setup\Installed Components\{unique bot GUID}
It adds the following registry entries:
HKEY_CURRENT_USER\SOFTWARE\Microsoft\
Active Setup\Installed Components\{unique bot GUID}
JavaScript = "{B64-encrypted Java script}"
HKEY_CURRENT_USER\SOFTWARE\Microsoft\
Active Setup\Installed Components\{unique bot GUID}
Rc4Encoded32 = "{Rc4 encoded hex values}"
HKEY_CURRENT_USER\SOFTWARE\Microsoft\
Active Setup\Installed Components\{unique bot GUID}
Rc4Encoded64 = "{Rc4 encoded hex values}"
Information Theft
This Trojan retrieves the following information from the affected system:
- User Startup folder path
- Volume GUID of root directory
- Computer Name
- User Name
NOTES:
This Trojan scans for the following registry key to check the .NET Framework version:
- HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\net framework setup\NDP\v2.0.50727
It scans for the following registry key to check if Windows PowerShell is installed:
- HKEY_CLASSES_ROOT\.ps1
It executes the Java script found in the following registry:
- HKEY_CURRENT_USER\SOFTWARE\Microsoft\Active Setup\Installed Components\{unique bot GUID}\JavaScript
The script decodes and executes a Base64-encoded PowerShell Script if the PowerShell installed in the system is version 1.0.
The PowerShell Script decrypts an RC4-encrypted shell code specific for 64-bit and 32-bit systems. The shell code it decrypts can be found in the following registry:
- HKEY_CURRENT_USER\SOFTWARE\Microsoft\Active Setup\Installed Components\{72507C54-3577-4830-815B-310007F6135A}\Rc4Encoded32
- HKEY_CURRENT_USER\SOFTWARE\Microsoft\Active Setup\Installed Components\{72507C54-3577-4830-815B-310007F6135A}\Rc4Encoded64
The shell code does the following:
- creates remote thread in all running processes
- connects to the following URL to send information:
- vcv.{BLOCKED} p.biz/gate.php
However, as of this writing, the said URL is no longer available.
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
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 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_CURRENT_USER\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
- Windows Host Process (RunDll) = "rundll32.exe javascript:"\..\mshtml,RunHTMLApplication ";eval((new%20ActiveXObject("WScript.Shell")).RegRead("HKCU\Software\Microsoft\Active%20Setup\Installed%20Components\{unique bot GUID}\JavaScript"));close();;"
- Windows Host Process (RunDll) = "rundll32.exe javascript:"\..\mshtml,RunHTMLApplication ";eval((new%20ActiveXObject("WScript.Shell")).RegRead("HKCU\Software\Microsoft\Active%20Setup\Installed%20Components\{unique bot GUID}\JavaScript"));close();;"
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_CURRENT_USER\SOFTWARE\Microsoft\Active Setup\Installed Components\{unique bot GUID}
Step 6
Restart in normal mode and scan your computer with your Trend Micro product for files detected as TROJ_PHASE.A. 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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