BKDR_ZEGOST.SML
Backdoor:Win32/Zegost.AD (Microsoft), Trojan.Win32.Staser.pxf (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: 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.
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:
- %Windows%\{8 random alphanumeric characters}.exe
(Note: %Windows% is the Windows folder, which is usually C:\Windows.)
Other System Modifications
This backdoor adds the following registry keys:
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\Qrstuv Xyabcdef Hij
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Enum\Root\LEGACY_QRSTUV_XYABCDEF_HIJ
HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\Qrstuv Xyabcdef Hij
HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Enum\Root\LEGACY_QRSTUV_XYABCDEF_HIJ
Other Details
This backdoor connects to the following possibly malicious URL:
- {BLOCKED}.{BLOCKED}.192.43:7788
- mcruandan.{BLOCKED}p.cc:7788
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
Scan your computer with your Trend Micro product and note files detected as BKDR_ZEGOST.SML
Step 3
Restart in Safe Mode
Step 4
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_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Qrstuv Xyabcdef Hij
- HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Enum\Root\LEGACY_QRSTUV_XYABCDEF_HIJ
- HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\Qrstuv Xyabcdef Hij
- HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Enum\Root\LEGACY_QRSTUV_XYABCDEF_HIJ
Step 5
Search and delete files detected as BKDR_ZEGOST.SML
Step 6
Restart in normal mode and scan your computer with your Trend Micro product for files detected as BKDR_ZEGOST.SML. 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.