Analysis by: Alvin Bacani
 PLATFORM:

Windows 2000, Windows Server 2003, Windows XP (32-bit, 64-bit), Windows Vista (32-bit, 64-bit), Windows 7 (32-bit, 64-bit)

 OVERALL RISK RATING:
 DAMAGE POTENTIAL:
 DISTRIBUTION POTENTIAL:
 REPORTED INFECTION:
 INFORMATION EXPOSURE:

  • Threat Type: Backdoor

  • Destructiveness: No

  • Encrypted: Yes

  • In the wild: Yes

  OVERVIEW

Infection Channel: 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 executes commands from a remote malicious user, effectively compromising the affected system.

  TECHNICAL DETAILS

File Size: 35,840 bytes
File Type: DLL
Initial Samples Received Date: 09 Sep 2013
Payload: Compromises system security

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:

  • %Program Files%\Internet Explorer\netidt.dll - detected as BKDR_SEDNIT.AE (for Windows XP and Below)
  • %Application Data%\netids.dll - detected as BKDR_SEDNIT.AE (for Windows Vista and Above)

(Note: %Program Files% is the default Program Files folder, usually C:\Program Files in Windows 2000, Server 2003, and XP (32-bit), Vista (32-bit), and 7 (32-bit), or C:\Program Files (x86) in Windows XP (64-bit), Vista (64-bit), and 7 (64-bit).. %Application Data% is the current user's Application Data folder, which is usually C:\Documents and Settings\{user name}\Application Data on Windows 2000, XP, and Server 2003, or C:\Users\{user name}\AppData\Roaming on Windows Vista and 7.)

Backdoor Routine

This backdoor executes the following commands from a remote malicious user:

  • downloads and execute possibly malicious files

It connects to the following URL(s) to send and receive commands from a remote malicious user:

  • http://{BLOCKED}.{BLOCKED}.221.10/~alex/cgi-bin/sptr.cgi
  • http://{BLOCKED}.{BLOCKED}.221.10/~alex/cgi-bin/qfa.cgi
  • http://{BLOCKED}.{BLOCKED}.221.10/~alex/cgi-bin/mpk.cgi
  • http://{BLOCKED}.{BLOCKED}.221.10/~alex/cgi-bin/brvc.cgi

NOTES:

This backdoor adds the following registry entries to enable its automatic execution at every system startup if the affected system is running Windows Vista or above:

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
NetIDS = RUNDLL32.EXE "%Application Data%\netids.dll",Init1

It may also registers as a system service to ensure its automatic execution at every system startup by adding the following registry keys if the affected system is running Windows XP or below:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\Network Identification Service
Type = "110"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\Network Identification Service
Start = "2"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\Network Identification Service
ErrorControl = "1"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\Network Identification Service
ImagePath = "%system%\svchost.exe -k ntsvcs"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\Network Identification Service
DisplayName = "Network Identification Service"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\Network Identification Service\parameters
ServiceDll = %Program Files%\Internet Explorer\netidt.dll

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\Network Identification Service
ServiceDllUnloadOnStop = "1"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows NT\CurrentVersion\SvcHost
ntsvcs = "Network Identification Service"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows NT\CurrentVersion\SvcHost\
ntsvcs
CoInitializeSecurityParam = "1"

This backdoor adds the following registry entries as part of its installation routine if the affected system is running Windows XP or below:

HKEY_CLASSES_ROOT\CLSID\{0B115951-84FD-43E7-A2D8-F3C4D36F4BEA}\
InProcServer32
Default = %Program Files%\Internet Explorer\netidt.dll

Upon connection to remote server, it sends the following information via HTTP Post:

  • Computer Name
  • Volume Serial Number
  • Operating System Information

  SOLUTION

Minimum Scan Engine: 9.300
FIRST VSAPI PATTERN FILE: 10.300.08
FIRST VSAPI PATTERN DATE: 26 Sep 2013
VSAPI OPR PATTERN File: 10.301.00
VSAPI OPR PATTERN Date: 26 Sep 2013

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

[ Learn More ]

Step 3

Scan your computer with your Trend Micro product to delete files detected as BKDR_SEDNIT.AE. 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.

Step 4

Search and delete these files

[ Learn More ]
There may be some component files that are hidden. Please make sure you check the Search Hidden Files and Folders checkbox in the More advanced options option to include all hidden files and folders in the search result.  
  • %Program Files%\Internet Explorer\netidt.dll
  • %Application Data%\netidt.dll

Step 5

Delete this registry value

[ Learn More ]

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
    • NetIDT = "RUNDLL32.EXE "%Application Data%\netidt.dll",Init1"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\SvcHost
    • ntsvcs = "Network Identification Service"

Step 6

Delete this registry key

[ Learn More ]

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. Before you could do this, you must restart in Safe Mode. For instructions on how to do this, you may refer to this page If the preceding step requires you to restart in safe mode, you may proceed to edit the system registry.

  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\SvcHost
    • ntsvcs
  • In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services
    • Network Identification Service
  • In HKEY_CLASSES_ROOT\CLSID
    • {0B115951-84FD-43E7-A2D8-F3C4D36F4BEA}

Step 7

Restart in normal mode and scan your computer with your Trend Micro product for files detected as BKDR_SEDNIT.AE. 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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