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TROJ_INJECT.YMNOY

March 01, 2017
 ALIASES:

VirTool:Win32/CeeInject.GF (Microsoft); RDN/Trojan-FKNI (McAfee); Trojan.Gen (Symantec); Trojan.Win32.Inject.aclit (Kaspersky); Trojan.Win32.Generic!BT (Sunbelt); Trojan horse Crypt6.AKPJ (AVG)

 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.

It deletes itself after execution.

  TECHNICAL DETAILS

File Size:

237,568 bytes

File Type:

EXE

Memory Resident:

No

Initial Samples Received Date:

01 Mar 2017

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.

Other System Modifications

This Trojan deletes the following files:

  • %System Root%\53828.bat

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

It adds the following registry entries:

HKEY_CURRENT_USER\Software\Microsoft
CtrlLogMaxSize = "3"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft
CtrlLogMaxSize = "3"

Dropping Routine

This Trojan drops the following files:

  • %Windows%\Tasks\Administrator_asriexp.job
  • %Windows%\Tasks\ASPNET_asriexp.job
  • %Windows%\Tasks\Guest_asriexp.job
  • %Windows%\Tasks\HelpAssistant_asriexp.job
  • %Windows%\Tasks\SUPPORT_388945a0_asriexp.job
  • %Windows%\Tasks\Wilbert_asriexp.job

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

Other Details

This Trojan deletes itself after execution.

This report is generated via an automated analysis system.

  SOLUTION

Minimum Scan Engine:

9.8

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

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
    • CtrlLogMaxSize = "3"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft
    • CtrlLogMaxSize = "3"

Step 3

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.
  • %Windows%\Tasks\Administrator_asriexp.job
  • %Windows%\Tasks\ASPNET_asriexp.job
  • %Windows%\Tasks\Guest_asriexp.job
  • %Windows%\Tasks\HelpAssistant_asriexp.job
  • %Windows%\Tasks\SUPPORT_388945a0_asriexp.job
  • %Windows%\Tasks\Wilbert_asriexp.job

Step 4

Scan your computer with your Trend Micro product to delete files detected as TROJ_INJECT.YMNOY. 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 5

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.

  • %System Root%\53828.bat


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