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Worm.Win32.ZLOB.AGV

June 13, 2019
 Modified by: Kiyoshi Obuchi
 ALIASES:

Win32/TrojanDownloader.Agent.NJO (ESET-NOD32); TrojanDownloader:Win32/Delf (Microsoft)

 PLATFORM:

Windows

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

  • Threat Type: Worm

  • Destructiveness: No

  • Encrypted: No

  • In the wild: Yes

  OVERVIEW

Infection Channel:

Downloaded from the Internet, Dropped by other malware


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 does not have any backdoor routine.

It does not have any information-stealing capability.

  TECHNICAL DETAILS

File Size:

18,716 bytes

File Type:

EXE

Memory Resident:

No

Initial Samples Received Date:

12 Jun 2019

Payload:

Modifies system registry

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:

  • {All Drives after %System Root%}\UCX.EXE
  • %System%\UCX.EXE

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

It adds the following mutexes to ensure that only one of its copies runs at any one time:

  • Apansoft

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
remotecontrol = "%System%\UCX.EXE"

Other System Modifications

This Worm deletes the following files:

  • %System%\UCX.EXE

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

It adds the following registry keys:

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
services\WinSock2\Parameters
Protocol_Catalog9 =

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
services\WinSock2
XSTUDIO_TCPIPDOG =

It also creates the following registry entry(ies) as part of its installation routine:

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
services\WinSock2\XSTUDIO_TCPIPDOG
1014 = %System%\mswsock.dll

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
services\WinSock2\Parameters\
Protocol_Catalog9\Catalog_Entries\000000000010
PackedCatalogItem = {Hex Values}

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
services\WinSock2\XSTUDIO_TCPIPDOG
1057 = %System%\vsocklib.dll

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
services\WinSock2\Parameters\
Protocol_Catalog9\Catalog_Entries\000000000011
PackedCatalogItem = {Hex Values}

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
services\WinSock2\XSTUDIO_TCPIPDOG
1058 = %System%\vsocklib.dll

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
services\WinSock2\XSTUDIO_TCPIPDOG
1001 = %System\mswsock.dll

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
services\WinSock2\Parameters\
Protocol_Catalog9\Catalog_Entries\000000000001
PackedCatalogItem = {Hex Values}

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
services\WinSock2\XSTUDIO_TCPIPDOG
1002 = %System%\mswsock.dll

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
services\WinSock2\Parameters\
Protocol_Catalog9\Catalog_Entries\000000000002
PackedCatalogItem = {Hex Values}

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
services\WinSock2\XSTUDIO_TCPIPDOG
1003 = %System%\mswsock.dll

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
services\WinSock2\Parameters\
Protocol_Catalog9\Catalog_Entries\000000000003
PackedCatalogItem = {Hex Values}

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
services\WinSock2\XSTUDIO_TCPIPDOG
1012 = %System%\mswsock.dll

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
services\WinSock2\Parameters\
Protocol_Catalog9\Catalog_Entries\000000000008
PackedCatalogItem = {Hex Values}

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
services\WinSock2\Parameters\
Protocol_Catalog9\Catalog_Entries\000000000012
PackedCatalogItem = {Hex Values}

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
services\WinSock2\XSTUDIO_TCPIPDOG
PathName = %System%\rundlll.dll

Propagation

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

Backdoor Routine

This Worm does not have any backdoor routine.

Rootkit Capabilities

This Worm does not have rootkit capabilities.

Download Routine

This Worm downloads the file from the following URL and renames the file when stored in the affected system:

  • http://{BLOCKED}1.{BLOCKED}w.com/rundlll2.dll

It saves the files it downloads using the following names:

  • %System%\rundlll.dll

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

Information Theft

This Worm does not have any information-stealing capability.

Other Details

This Worm does not exploit any vulnerability.

  SOLUTION

Minimum Scan Engine:

9.850

FIRST VSAPI PATTERN FILE:

15.168.04

FIRST VSAPI PATTERN DATE:

12 Jun 2019

VSAPI OPR PATTERN File:

15.169.00

VSAPI OPR PATTERN Date:

13 Jun 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

Restart in Safe Mode

[ Learn More ]

Step 3

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
    • remotecontrol = %System%\UCX.EXE

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\ControlSet001\services\WinSock2
    • XSTUDIO_TCPIPDOG
  • In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\services\WinSock2\Parameters
    • Protocol_Catalog9

Step 5

Restart in normal mode and scan your computer with your Trend Micro product for files detected as Worm.Win32.ZLOB.AGV. 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 6

Scan your computer with your Trend Micro product to delete files detected as Worm.Win32.ZLOB.AGV. 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 the following Trend Micro Support pages for more information:


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