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TROJ_DIALR6.TOMA

October 08, 2019
 ALIASES:

Dialer:Win32/WebDial.A [non_writable_container] (Microsoft); Dialer-RAS.c.gen. (McAfee); Dialer.Generic (Symantec); Trojan.Win32.Scar.omgz (Kaspersky); Dial/WebDial-A (Sophos); BehavesLike.Win32.Malware.wsc (mx-v) (Sunbelt)

 PLATFORM:

Windows

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

  • Threat Type: Trojan

  • Destructiveness: No

  • Encrypted:

  • In the wild: Yes

  OVERVIEW


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

  TECHNICAL DETAILS

File Size:

48,128 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

08 Oct 2019

Arrival Details

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

  • %windows%\{malware file name}.exe

It adds the following processes:

  • %System%\svchost.exe -k netsvcs

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

Autostart Technique

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

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
3ae2b1738a578affb7a2f6bb641c23b597ef913e = "%windows%\{malware file name}.exe -m"

Other System Modifications

This Trojan deletes the following files:

  • %Start Menu%\Programs\3ae2b1738a578affb7a2f6bb641c23b597ef913e.lnk
  • %User Startup%\3ae2b1738a578affb7a2f6bb641c23b597ef913e.lnk

(Note: %Start Menu% is the current user's Start Menu folder, which is usually C:\Windows\Start Menu or C:\Documents and Settings\{User name}\Start Menu on Windows 2000(32-bit), XP, and Server 2003(32-bit), or C:\Users\{user name}\AppData\Roaming\Microsoft\Windows\Start Menu on Windows Vista, 7, 8, 8.1, 2008(64-bit), 2012(64-bit) and 10(64-bit).. %User Startup% is the current user's Startup folder, which is usually C:\Windows\Profiles\{user name}\Start Menu\Programs\Startup on Windows 98 and ME, C:\WINNT\Profiles\{user name}\Start Menu\Programs\Startup on Windows NT, C:\Documents and Settings\{User name}\Start Menu\Programs\Startup on Windows 2003(32-bit), XP and 2000(32-bit), or C:\Users\{user name}\AppData\Roaming\Microsoft\Windows\Start Menu\Programs\Startup on Windows Vista, 7, 8, 8.1, 2008(64-bit), 2012(64-bit), 10(64-bit).)

It adds the following registry keys:

HKEY_CURRENT_USER\Software\Webdialer

HKEY_CURRENT_USER\Software\Webdialer\
105-1-19-2

HKEY_LOCAL_MACHINE\Software\Microsoft\
Windows\CurrentVersion\Uninstall\
Webdialer - www.lesbianteens.de Reg.N:105-1-19-2

It adds the following registry entries:

HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\
Microsoft\Windows\CurrentVersion\
Uninstall\Webdialer - www.lesbianteens.de Reg.N:105-1-19-2
DisplayName = "WebDialer - www.lesbianteens.de Reg.N:105-1-19-2"

HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\
Microsoft\Windows\CurrentVersion\
Uninstall\Webdialer - www.lesbianteens.de Reg.N:105-1-19-2
UninstallString = "%windows%\{malware file name}.exe -m -u"

HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\
Microsoft\Tracing\3ae2b1738a578affb7a2f6bb641c23b597ef913e_RASMANCS
EnableFileTracing = "0"

HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\
Microsoft\Tracing\3ae2b1738a578affb7a2f6bb641c23b597ef913e_RASMANCS
EnableConsoleTracing = "0"

HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\
Microsoft\Tracing\3ae2b1738a578affb7a2f6bb641c23b597ef913e_RASMANCS
FileTracingMask = "4294901760"

HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\
Microsoft\Tracing\3ae2b1738a578affb7a2f6bb641c23b597ef913e_RASMANCS
ConsoleTracingMask = "4294901760"

HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\
Microsoft\Tracing\3ae2b1738a578affb7a2f6bb641c23b597ef913e_RASMANCS
MaxFileSize = "1048576"

HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\
Microsoft\Tracing\3ae2b1738a578affb7a2f6bb641c23b597ef913e_RASMANCS
FileDirectory = "%windir%\tracing"

It deletes the following registry keys:

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run\
3ae2b1738a578affb7a2f6bb641c23b597ef913e

Dropping Routine

This Trojan drops the following files:

  • %Start Menu%\3ae2b1738a578affb7a2f6bb641c23b597ef913e.lnk
  • %Desktop%\3ae2b1738a578affb7a2f6bb641c23b597ef913e.lnk

(Note: %Start Menu% is the current user's Start Menu folder, which is usually C:\Windows\Start Menu or C:\Documents and Settings\{User name}\Start Menu on Windows 2000(32-bit), XP, and Server 2003(32-bit), or C:\Users\{user name}\AppData\Roaming\Microsoft\Windows\Start Menu on Windows Vista, 7, 8, 8.1, 2008(64-bit), 2012(64-bit) and 10(64-bit).. %Desktop% is the current user's desktop, which is usually C:\Documents and Settings\{User Name}\Desktop on Windows 2000(32-bit), XP, and Server 2003(32-bit), or C:\Users\{user name}\Desktop on Windows Vista, 7, 8, 8.1, 2008(64-bit), 2012(64-bit) and 10(64-bit).)

This report is generated via an automated analysis system.

  SOLUTION

Minimum Scan Engine:

9.850

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

Identify and terminate files detected as TROJ_DIALR6.TOMA

[ Learn More ]
  1. Windows Task Manager may not display all running processes. In this case, please use a third-party process viewer, preferably Process Explorer, to terminate the malware/grayware/spyware file. You may download the said tool here.
  2. If the detected file is displayed in either Windows Task Manager or Process Explorer but you cannot delete it, restart your computer in safe mode. To do this, refer to this link for the complete steps.
  3. If the detected file is not displayed in either Windows Task Manager or Process Explorer, continue doing the next steps.

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_CURRENT_USER\Software
    • Webdialer
  • In HKEY_CURRENT_USER\Software\Webdialer
    • 105-1-19-2
  • In HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Uninstall
    • Webdialer - www.lesbianteens.de Reg.N:105-1-19-2

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
    • 3ae2b1738a578affb7a2f6bb641c23b597ef913e = "%windows%\{malware file name}.exe -m"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\Microsoft\Windows\CurrentVersion\Uninstall\Webdialer - www.lesbianteens.de Reg.N:105-1-19-2
    • DisplayName = "WebDialer - www.lesbianteens.de Reg.N:105-1-19-2"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\Microsoft\Windows\CurrentVersion\Uninstall\Webdialer - www.lesbianteens.de Reg.N:105-1-19-2
    • UninstallString = "%windows%\{malware file name}.exe -m -u"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\Microsoft\Tracing\3ae2b1738a578affb7a2f6bb641c23b597ef913e_RASMANCS
    • EnableFileTracing = "0"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\Microsoft\Tracing\3ae2b1738a578affb7a2f6bb641c23b597ef913e_RASMANCS
    • EnableConsoleTracing = "0"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\Microsoft\Tracing\3ae2b1738a578affb7a2f6bb641c23b597ef913e_RASMANCS
    • FileTracingMask = "4294901760"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\Microsoft\Tracing\3ae2b1738a578affb7a2f6bb641c23b597ef913e_RASMANCS
    • ConsoleTracingMask = "4294901760"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\Microsoft\Tracing\3ae2b1738a578affb7a2f6bb641c23b597ef913e_RASMANCS
    • MaxFileSize = "1048576"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\Microsoft\Tracing\3ae2b1738a578affb7a2f6bb641c23b597ef913e_RASMANCS
    • FileDirectory = "%windir%\tracing"

Step 6

Search and delete these components

[ Learn More ]
There may be some components 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.
  • %Start Menu%\3ae2b1738a578affb7a2f6bb641c23b597ef913e.lnk
  • %Desktop%\3ae2b1738a578affb7a2f6bb641c23b597ef913e.lnk

Step 7

Restart in normal mode and scan your computer with your Trend Micro product for files detected as TROJ_DIALR6.TOMA. 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

Restore this file from backup only Microsoft-related files will be restored. If this malware/grayware also deleted files related to programs that are not from Microsoft, please reinstall those programs on you computer again.

  • %Start Menu%\Programs\3ae2b1738a578affb7a2f6bb641c23b597ef913e.lnk
  • %User Startup%\3ae2b1738a578affb7a2f6bb641c23b597ef913e.lnk

Step 9

Restore these deleted registry keys/values from backup

*Note: Only Microsoft-related keys/values will be restored. If the malware/grayware also deleted registry keys/values related to programs that are not from Microsoft, please reinstall those programs on your computer.

  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
    • 3ae2b1738a578affb7a2f6bb641c23b597ef913e


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