Windows
This threat is a Master Boot Record (MBR) wiper that infected systems of a major Korean electric utility.
To get a one-glance comprehensive view of the behavior of this Trojan, refer to the Threat Diagram shown below.
This Trojan may be dropped by other malware.
Arrival Details
This Trojan may be dropped by the following malware:
Installation
This Trojan drops the following copies of itself into the affected system:
(Note: %System% is the Windows system folder, where it usually is C:\Windows\System32 on all Windows operating system versions.)
Autostart Technique
This Trojan adds the following entries to allow itself to run on safe mode:
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Control\SafeBoot\Minimal\
{random data}
(Default) = "Service"
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Control\SafeBoot\Network\
{random data}
(Default) = "Service"
It adds the following keys to allow itself to run on safe mode:
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Control\SafeBoot\Minimal\
{random data}
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Control\SafeBoot\Network\
{random data}
It registers its dropped component as a system service to ensure its automatic execution at every system startup. It does this by creating the following registry entries:
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\{random data}\Parameters
ServiceDll = "%System%\{random file name}.dll"
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\{random data}\Parameters
ServiceMain = "ServiceMain"
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\{random data}
ImagePath = "%SystemRoot%\System32\svchost.exe -k {random value}"
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\{random data}
DisplayName = "{random value}"
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\{random data}
Description = "{random description}"
It registers its dropped component as a system service to ensure its automatic execution at every system startup. It does this by creating the following registry keys:
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\{random data}\Parameters
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\{random data}
Other System Modifications
This Trojan adds the following registry keys:
HKEY_LOCAL_MACHINE\SOFTWARE\PcaSvcc
It adds the following registry entries:
HKEY_LOCAL_MACHINE\SOFTWARE\PcaSvcc
number = "{random value in hex}"
HKEY_LOCAL_MACHINE\SOFTWARE\PcaSvcc
year = "{current year in hex}"
HKEY_LOCAL_MACHINE\SOFTWARE\PcaSvcc
month = "{current month in hex}"
HKEY_LOCAL_MACHINE\SOFTWARE\PcaSvcc
day = "{current day in hex}"
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows NT\CurrentVersion\SvcHost
{random value} = "{random data}"
HKEY_LOCAL_MACHINE\SOFTWARE\PcaSvcc
finish = "1"
NOTES:
If the Operating System (OS) is Vista or higher and is 64-bit, it drops and executes the following malware:
This Trojan overwrites the Master Boot record (MBR) of the affected system with the strings, Who Am I?.
After infection, it restarts the system and it displays the following:
Where {random file name} can be any of the following:
Where {random data} can be any of the following:
TROJ_WHAIM.A checks if the current date and time is Dec 10, 2014 11:00 AM or later. If it meets this condition, it sets the registry, HKEY_LOCAL_MACHINE\SOFTWARE\PcaSvcc\finish to 1, thus triggering the MBR infection. Otherwise, it sleeps for a minute and checks the system time again.
Step 1
Restore your system's Master Boot Record (MBR)
To restore your system's Master Boot Record (MBR):
• On Windows 2000, XP, and Server 2003:
• On Windows Vista, 7, and Server 2008:
• On Windows 8, 8.1, and Server 2012:
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
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 4
Remove the malware/grayware file that dropped/downloaded TROJ_WHAIM.A. (Note: Please skip this step if the threat(s) listed below have already been removed.)
Step 5
Remove malware/grayware files dropped/downloaded by TROJ_WHAIM.A. (Note: Please skip this step if the threats listed below have already been removed.)
Step 6
Since this malware cannot be removed in normal and safe mode, it is necessary to restart using the Windows Recovery Console. To restart the system using the Windows Recovery Console:
• On Windows XP and Server 2003 systems:
• On Windows Vista, 7, and Server 2008 systems:
• On Windows 8, 8.1, and Server 2012 systems:
Step 7
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.
Step 8
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.
Step 9
Restart in normal mode and scan your computer with your Trend Micro product for files detected as TROJ_WHAIM.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.