Analysis by: Byron Jon Gelera
ALIASES:

Trojan:Win32/Dynamer!ac (Microsoft); Trojan-Ransom.Win32.Crypmodadv.wys (Kaspersky)

 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: 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.

  TECHNICAL DETAILS

File Size: 13,312 bytes
File Type: EXE
Memory Resident: No
Initial Samples Received Date: 15 Jul 2016
Payload: Encrypts 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.

Other System Modifications

This Trojan modifies the following file(s):

  • It encrypts files and appends the extension .remind

Other Details

This Trojan encrypts files with the following extensions:

  • .adi
  • .adt
  • .altr
  • .arw
  • .asmx
  • .asp
  • .aspx
  • .csv
  • .doc
  • .docx
  • .dwf
  • .html
  • .jpg
  • .msg
  • .odt
  • .pdf
  • .php
  • .png
  • .ppt
  • .pptx
  • .psd
  • .qbb
  • .rpt
  • .sldprt
  • .sql
  • .txt
  • .xls
  • .xlsx
  • .xml
  • sln

It drops the following file(s)/component(s):

  • {All folders in all disk drive}\DECRYPT_YOUR_FILES.HTML - Ransom Note

NOTES:
The ransom note DECRYPT_YOUR_FILES.HTML contains the following:

  SOLUTION

Minimum Scan Engine: 9.800
FIRST VSAPI PATTERN FILE: 12.654.08
FIRST VSAPI PATTERN DATE: 15 Jul 2016
VSAPI OPR PATTERN File: 12.655.00
VSAPI OPR PATTERN Date: 16 Jul 2016

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.  
  • {All folders in all disk drive}\DECRYPT_YOUR_FILES.HTML

Step 4

Scan your computer with your Trend Micro product to delete files detected as RANSOM_RUSHTEAR.A. 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 5

Restore encrypted files from backup.


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