Worm.Win32.NEERIS.A

November 19, 2019
 Analysis by: Jay Garcia
 ALIASES:

Net-Worm.Win32.Kolab.fbl (Kaspersky); VirTool:Win32/DelfInject.gen!AU [generic] (Microsoft)

 PLATFORM:

Windows

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

  • Threat Type: Worm

  • Destructiveness: No

  • Encrypted: Yes

  • In the wild: Yes

  OVERVIEW

Infection Channel:

Dropped by other malware, Downloaded from the Internet, Propagates via removable drives

This Worm arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites.

It drops an AUTORUN.INF file to automatically execute the copies it drops when a user accesses the drives of an affected system. It exploits software vulnerabilities to propagate to other computers across a network.

It also has rootkit capabilities, which enables it to hide its processes and files from the user.

It connects to certain websites to send and receive information. However, as of this writing, the said sites are inaccessible. It deletes itself after execution.

  TECHNICAL DETAILS

File Size:

101,376 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

11 Nov 2019

Payload:

Compromises system security, Connects to URLs/IPs

Arrival Details

This Worm 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 Worm drops the following copies of itself into the affected system:

  • %Windows%\system\netmon.exe

(Note: %Windows% is the Windows folder, where it usually is C:\Windows on all Windows operating system versions.)

Autostart Technique

This Worm adds the following registry entries to enable its automatic execution at every system startup:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Run
netmon = "%Windows%\system\netmon.exe"

It registers its dropped component as a system service to ensure its automatic execution at every system startup. It does this by creating the following registry entries:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\sysdrv32
Type = "1"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\sysdrv32
Start = "3"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\sysdrv32
ErrorControl = "1"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\sysdrv32
ImagePath = "\??\%System%\drivers\sysdrv32.sys"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\sysdrv32
DisplayName = "Play Port I/O Driver"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\sysdrv32
Group = "SST wanport drivers"

Other System Modifications

This Worm adds the following registry keys:

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Control\SafeBoot\Minimal\
netmon32

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Control\SafeBoot\Network\
netmon32

Propagation

This Worm drops the following copy(ies) of itself in all removable drives:

  • {Removable drive}:\smartkey.exe

It drops an AUTORUN.INF file to automatically execute the copies it drops when a user accesses the drives of an affected system.

It exploits the following software vulnerabilities to propagate to other computers across a network:

Rootkit Capabilities

This Worm also has rootkit capabilities, which enables it to hide its processes and files from the user.

Dropping Routine

This Worm drops the following files:

  • %System%\drivers\sysdrv32.sys - detected as RTKT_TCPAGENT.W
  • {Removable drive}:\autorun.inf

(Note: %System% is the Windows system folder, where it usually is C:\Windows\System32 on all Windows operating system versions.)

Other Details

This Worm connects to the following website to send and receive information:

  • {BLOCKED}.{BLOCKED}.com:449

However, as of this writing, the said sites are inaccessible.

It deletes itself after execution.

  SOLUTION

Minimum Scan Engine:

9.300

FIRST VSAPI PATTERN FILE:

15.496.02

FIRST VSAPI PATTERN DATE:

15 Nov 2019

VSAPI OPR PATTERN File:

15.497.00

VSAPI OPR PATTERN Date:

16 Nov 2019

Step 1

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 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

Restart in Safe Mode

[ Learn More ]

Step 4

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.

  • In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services
    • sysdrv32
  • In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\SafeBoot\Minimal
    • netmon32
  • In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\SafeBoot\Network
    • netmon32

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_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
    • netmon = "%Windows%\system\netmon.exe"

Step 6

Search and delete this file

[ Learn More ]
There may be some 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.
  • %Windows%\system\netmon.exe
  • %System%\drivers\sysdrv32.sys
  • {Removable drive}:\smartkey.exe

Step 7

Restart in normal mode and scan your computer with your Trend Micro product for files detected as Worm.Win32.NEERIS.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.

Step 8

Download and apply these security patches Refrain from using these products until the appropriate patches have been installed. Trend Micro advises users to download critical patches upon release by vendors. Microsoft Security Bulletin MS17-010


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