Analysis by: Michael Jay Villanueva

ALIASES:

Trojan.Pidief.X (Symantec); Troj/PDFDoc-O (Sophos); PDF/TrojanDropper.Agent.AP (ESET-NOD32)

 PLATFORM:

Windows

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

  • Threat Type: Trojan

  • Destructiveness: No

  • Encrypted: No

  • In the wild: Yes

  OVERVIEW

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

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.

  TECHNICAL DETAILS

File Size: 61,746 bytes
File Type: PDF
Memory Resident: No
Initial Samples Received Date: 20 Jul 2017
Payload: Drops files, Deletes files, Displays message/message boxes

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.

Installation

This Trojan drops and executes the following files:

  • %User Temp%\A9R{Random}.tmp\DOC34175250.docm ← contains malicious macro, detected as W2KM_DLOADR.YYTAV

It creates the following folders:

  • %User Temp%\A9R{Random}.tmp

(Note: %User Temp% is the user's temporary folder, where it usually is C:\Documents and Settings\{user name}\Local Settings\Temp on Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\Users\{user name}\AppData\Local\Temp on Windows Vista (32- and 64-bit), Windows 7 (32- and 64-bit), Windows 8 (32- and 64-bit), Windows 8.1 (32- and 64-bit), Windows Server 2008, and Windows Server 2012.)

Other Details

This Trojan does the following:

  • It deletes the created folder and dropped file once it is closed.

NOTES:

The PDF file contains the following fake details luring users to enable macro content/program:

  SOLUTION

Minimum Scan Engine: 9.850
FIRST VSAPI PATTERN FILE: 13.544.04
FIRST VSAPI PATTERN DATE: 20 Jul 2017
VSAPI OPR PATTERN File: 13.545.00
VSAPI OPR PATTERN Date: 21 Jul 2017

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

Remove malware/grayware files dropped/downloaded by PDF_DOCDROP.YYTAV. (Note: Please skip this step if the threats listed below have already been removed.)

    • W2KM_DLOADR.YYTAV

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.
  • %User Temp%\A9R{Random}.tmp

Step 5

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%\A9R{Random}.tmp\DOC34175250.docm

Step 6

Scan your computer with your Trend Micro product to delete files detected as PDF_DOCDROP.YYTAV. 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 7

Enable the macro virus protection in Microsoft Office Applications

[ Learn More ]


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