BKDR_ZEGOST.TIDAFAU
Backdoor:Win32/Zegost (Microsoft)
Windows
Threat Type: Backdoor
Destructiveness: No
Encrypted: No
In the wild: Yes
OVERVIEW
Downloaded from the Internet, Dropped by other malware
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 may be dropped by other malware.
It executes commands from a remote malicious user, effectively compromising the affected system. However, as of this writing, the said sites are inaccessible.
It deletes the initially executed copy of itself.
TECHNICAL DETAILS
184,320 bytes
EXE
Yes
23 Jul 2018
Connects to URLs/IPs
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.
It may be dropped by the following malware:
- TROJ_DLOADR.AUSUML
Installation
This Backdoor drops the following copies of itself into the affected system:
- %System%\seser.exe
(Note: %System% is the Windows system folder, where it usually is C:\Windows\System32 on all Windows operating system versions.)
Autostart Technique
This Backdoor registers itself as a system service to ensure its automatic execution at every system startup by adding the following registry entries:
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\{random name}
Description = {random}
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\{random name}
MarkTime = {yyyy-mm-dd hh:mm}
It adds and runs the following services:
- Service path: %System%\seser.exe
- Service name: {random}
(Note: %System% is the Windows system folder, where it usually is C:\Windows\System32 on all Windows operating system versions.)
It registers as a system service to ensure its automatic execution at every system startup by adding the following registry keys:
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\{random name}
Backdoor Routine
This Backdoor executes the following commands from a remote malicious user:
- File manager
- Download and execute file/s
- Remote text chat
- Remote shell execution
- List running processes
- Take Screenshots
- Shutdown/restart machine
- Keylogger
- Update itself
- Copy/Empty Clipboard
It connects to the following URL(s) to send and receive commands from a remote malicious user:
- {BLOCKED}.{BLOCKED}.179.217:5200
However, as of this writing, the said sites are inaccessible.
Other Details
This Backdoor deletes the initially executed copy of itself
SOLUTION
9.850
14.400.02
24 Jul 2018
14.401.00
25 Jul 2018
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
Remove the malware/grayware file that dropped/downloaded BKDR_ZEGOST.TIDAFAU. (Note: Please skip this step if the threat(s) listed below have already been removed.)
- TROJ_DLOADR.AUSUML
Step 4
Restart in Safe Mode
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.
- In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services
- {random name}
- {random name}
Step 6
Restart in normal mode and scan your computer with your Trend Micro product for files detected as BKDR_ZEGOST.TIDAFAU. 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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