BKDR_CAPHAW.XBC
Backdoor:Win32/Caphaw.A (Microsoft), Win32/Kryptik.BXQX trojan (ESET)
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: Backdoor
Destructiveness: No
Encrypted:
In the wild: Yes
OVERVIEW
This backdoor 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 the initially executed copy of itself.
TECHNICAL DETAILS
Arrival Details
This backdoor 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 backdoor drops the following copies of itself into the affected system:
- %Application Data%\{random folder found}\{filename found in %System%}
(Note: %System% is the Windows system folder, which is usually C:\Windows\System32.)
Autostart Technique
This backdoor adds the following registry entries to enable its automatic execution at every system startup:
HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
{random Base64 string} = "%Application Data%\{random folder found}\{filename found in %System%}"
Other System Modifications
This backdoor adds the following registry entries as part of its installation routine:
HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Internet Settings\
Zones\3
2500 = "3"
It modifies the following registry entries:
HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Internet Settings\
Zones\3
1609 = "3"
(Note: The default value data of the said registry entry is "1".)
Other Details
This backdoor connects to the following possibly malicious URL:
- http://{randomly generated string}.{BLOCKED}ty.cc/
- http://{randomly generated string}.{BLOCKED}rg.cc/
- http://{randomly generated string}.{BLOCKED}pr.cc/
It deletes the initially executed copy of itself
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 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
- {random Base64 string} = "%Application Data%\{random folder found}\{filename found in %System%}"
- {random Base64 string} = "%Application Data%\{random folder found}\{filename found in %System%}"
- In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Internet Settings\Zones\3
- 2500 = "3"
- 2500 = "3"
Step 4
Restore this modified 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\Internet Settings\Zones\3
- From: 1609 = "3"
To: 1609 = "1"
- From: 1609 = "3"
Step 5
Search and delete this file
Step 6
Restart in normal mode and scan your computer with your Trend Micro product for files detected as BKDR_CAPHAW.XBC. 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.
Did this description help? Tell us how we did.