Backdoor.Win32.SDDOS.A
Trojan:Win32/Bulta!rfn [non_writable_container] (MICROSOFT); Backdoor.Win32.Sdbot.agiy (KASPERSKY)
Windows
![](/vinfo/imgFiles/legend.jpg)
Threat Type: Backdoor
Destructiveness: No
Encrypted: Yes
In the wild:
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 executes commands from a remote malicious user, effectively compromising the affected system.
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 files:
- %Application Data%\WindowsUpdata\.temp.fortest - main malware was ran without admin privilege
- %Windows%\WindowsUpdata\.temp.fortest - main malware was ran with admin privilege
(Note: %Application Data% is the current user's Application Data folder, which is usually C:\Documents and Settings\{user name}\Application Data on Windows 2000(32-bit), XP, and Server 2003(32-bit), or C:\Users\{user name}\AppData\Roaming on Windows Vista, 7, 8, 8.1, 2008(64-bit), 2012(64-bit) and 10(64-bit).. %Windows% is the Windows folder, where it usually is C:\Windows on all Windows operating system versions.)
It drops and executes the following files:
- %Application Data%\WindowsUpdata\{random}.exe - main malware was ran without admin privilege
- %Windows%\WindowsUpdata\{random}.exe - main malware was ran with admin privilege
(Note: %Application Data% is the current user's Application Data folder, which is usually C:\Documents and Settings\{user name}\Application Data on Windows 2000(32-bit), XP, and Server 2003(32-bit), or C:\Users\{user name}\AppData\Roaming on Windows Vista, 7, 8, 8.1, 2008(64-bit), 2012(64-bit) and 10(64-bit).. %Windows% is the Windows folder, where it usually is C:\Windows on all Windows operating system versions.)
It adds the following processes:
- %System%\cmd.exe /c del {Malware path and name} > nul - delete original malware
(Note: %System% is the Windows system folder, where it usually is C:\Windows\System32 on all Windows operating system versions.)
It creates the following folders:
- %Application Data%\WindowsUpdata - main malware was ran without admin privilege
- %Windows%\WindowsUpdata - main malware was ran with admin privilege
(Note: %Application Data% is the current user's Application Data folder, which is usually C:\Documents and Settings\{user name}\Application Data on Windows 2000(32-bit), XP, and Server 2003(32-bit), or C:\Users\{user name}\AppData\Roaming on Windows Vista, 7, 8, 8.1, 2008(64-bit), 2012(64-bit) and 10(64-bit).. %Windows% is the Windows folder, where it usually is C:\Windows on all Windows operating system versions.)
It adds the following mutexes to ensure that only one of its copies runs at any one time:
- siukit.cn
Autostart Technique
This Backdoor adds the following registry entries to enable its automatic execution at every system startup:
HKEY_LOCAL_MACHINE\Software\Microsoft\
Windows\CurrentVersion\Run
{Random Malware Name}.exe = %Windows%\WindowsUpdata\{random}.exe - main malware was ran with admin privilege
HKEY_LOCAL_MACHINE\Software\Microsoft\
Windows\CurrentVersion\Run
{Random Malware Name}.exe = %Application Data%\WindowsUpdata\{Random}.exe - main malware was ran without admin privilege
Other System Modifications
This Backdoor modifies the following registry entries:
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Security Center
UACDisableNotify = 0
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Policies\
System
EnableLUA = 0
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Policies\
System
PromptOnSecureDesktop = 0
Backdoor Routine
This Backdoor executes the following commands from a remote malicious user:
- Perforn DDoS Attacks on specific IP address
- Download files
It connects to the following URL(s) to send and receive commands from a remote malicious user:
- {BLOCKED}.{BLOCKED}.133.49:2553
Denial of Service (DoS) Attack
This Backdoor is capable of performing various network denial-of-service (DoS) attacks:
- {BLOCKED}.{BLOCKED}.153.99:1024
- {BLOCKED}.{BLOCKED}.210.236:1024
Information Theft
This Backdoor gathers the following data:
- Windows Version
- Current Memory Usage
- System Hardware Information
- Username
- Computer name
- IP address
Other Details
This Backdoor does the following:
- It requires the following file in order to perform its other routines:
- Config.ini
- It sends the gathered information to its server.
SOLUTION
Step 1
Trend Micro Predictive Machine Learning detects and blocks malware at the first sign of its existence, before it executes on your system. When enabled, your Trend Micro product detects this malware under the following machine learning name:
-
Troj.Win32.TRX.XXPE50FFF035
Step 2
Before doing any scans, Windows 7, Windows 8, Windows 8.1, and Windows 10 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
Restart in Safe Mode
Step 5
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_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Run
- {Random Malware Name}.exe = %Application Data%\WindowsUpdata\{Random}.exe
- {Random Malware Name}.exe = %Application Data%\WindowsUpdata\{Random}.exe
- In HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Run
- {Random Malware Name}.exe = %Windows%\WindowsUpdata\{random}.exe
- {Random Malware Name}.exe = %Windows%\WindowsUpdata\{random}.exe
Step 6
Restore this modified registry value
Important: Editing the Windows Registry incorrectly can lead to irreversible system malfunction. Please do this only if you know how to or you can seek your system administrator’s help. You may also check out this Microsoft article first before modifying your computer's registry.
- In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Security Center
- From: UACDisableNotify = 0
To: UACDisableNotify = {Default}
- From: UACDisableNotify = 0
- In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Policies\System
- From: EnableLUA = 0
To: EnableLUA = {Default}
- From: EnableLUA = 0
- In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Policies\System
- From: PromptOnSecureDesktop = 0
To: PromptOnSecureDesktop = {Default}
- From: PromptOnSecureDesktop = 0
Step 7
Search and delete this folder
- %Application Data%\WindowsUpdata
- %Windows%\WindowsUpdata
Step 8
Restart in normal mode and scan your computer with your Trend Micro product for files detected as Backdoor.Win32.SDDOS.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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