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Trojan.PS1.MSAIHA.SM

April 15, 2019
 Analysis by: John Rey Canon
 PLATFORM:

Windows

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

  • Threat Type: Trojan

  • Destructiveness: No

  • Encrypted: Yes

  • In the wild: Yes

  OVERVIEW

Infection Channel:

Dropped by other malware, Downloaded from the Internet


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 restarts the affected system.

  TECHNICAL DETAILS

File Size:

570,880 bytes

File Type:

Other

Memory Resident:

Yes

Initial Samples Received Date:

12 Apr 2019

Payload:

Deletes files, Connects to URLs/IPs

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:

  • %Application Data%\Microsoft\{Random 8 Letters}\{Random 12 Letters}.exe %Application Data%\Microsoft\{Random 8 Letters}\{Random 10 Letters} %Application Data%\Microsoft\{Random 8 Letters}\{Random 7 Letters}.dll

(Note: %Application Data% is the current user's Application Data folder, which is usually C:\Documents and Settings\{user name}\Application Data on Windows 2000, XP, and Server 2003, or C:\Users\{user name}\AppData\Roaming on Windows Vista, 7, and 8.)

It creates the following folders:

  • %Application Data%\Microsoft\{Random 8 Letters}

(Note: %Application Data% is the current user's Application Data folder, which is usually C:\Documents and Settings\{user name}\Application Data on Windows 2000, XP, and Server 2003, or C:\Users\{user name}\AppData\Roaming on Windows Vista, 7, and 8.)

Other System Modifications

This Trojan deletes the following files:

  • %Application Data%\Microsoft\{Random 8 Letters}\{Random 8 Letters}.zip

(Note: %Application Data% is the current user's Application Data folder, which is usually C:\Documents and Settings\{user name}\Application Data on Windows 2000, XP, and Server 2003, or C:\Users\{user name}\AppData\Roaming on Windows Vista, 7, and 8.)

Download Routine

This Trojan accesses the following websites to download files:

  • http://sertaomax003.{BLOCKED}st.net/yak1009/hfmacttpo.zip

It saves the files it downloads using the following names:

  • %Application Data%\Microsoft\{Random 8 Letters}\{Random 8 Letters}.zip → Encrypted ZIP File

(Note: %Application Data% is the current user's Application Data folder, which is usually C:\Documents and Settings\{user name}\Application Data on Windows 2000, XP, and Server 2003, or C:\Users\{user name}\AppData\Roaming on Windows Vista, 7, and 8.)

Other Details

This Trojan restarts the affected system.

It does the following:

  • It decrypts the downloaded zip.
  • It extracts the contents of the zip file and rename them as:
    • %Application Data%\Microsoft\{Random 8 Letters}\{Random 12 Letters}.exe → non-malicious
    • %Application Data%\Microsoft\{Random 8 Letters}\{Random 7 Letters}.dll
    • %Application Data%\Microsoft\{Random 8 Letters}\{Random 10 Letters}

(Note: %Application Data% is the current user's Application Data folder, which is usually C:\Documents and Settings\{user name}\Application Data on Windows 2000, XP, and Server 2003, or C:\Users\{user name}\AppData\Roaming on Windows Vista, 7, and 8.)

  SOLUTION

Minimum Scan Engine:

9.850

FIRST VSAPI PATTERN FILE:

14.934.04

FIRST VSAPI PATTERN DATE:

12 Apr 2019

VSAPI OPR PATTERN File:

14.935.00

VSAPI OPR PATTERN Date:

13 Apr 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

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.
  • %Application Data%\Microsoft\{Random 8 Letters}\{Random 12 Letters}.exe → non-malicious
  • %Application Data%\Microsoft\{Random 8 Letters}\{Random 7 Letters}.dll
  • %Application Data%\Microsoft\{Random 8 Letters}\{Random 10 Letters}

Step 4

Search and delete these folders

[ Learn More ]
Please make sure you check the Search Hidden Files and Folders checkbox in the More advanced options option to include all hidden folders in the search result.  
  • %Application Data%\Microsoft\{Random 8 Letters}

Step 5

Scan your computer with your Trend Micro product to delete files detected as Trojan.PS1.MSAIHA.SM. 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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