Analysis by: Francis Xavier Antazo

 ALIASES:

Ransom:Win32/Petya.A (Microsoft); Win32/Diskcoder.Petya.A (ESET); Trojan-Ransom.Win32.Petr.a (Kaspersky); Ransom_r.DD (AVG);

 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: Downloaded from the Internet

Known as PETYA crypto-ransomware, this malware displays ransom notes at system startup and overwrites Master Boot Record (MBR). It also abuses the cloud storage service, Dropbox for its infection vector. It deviated from other variants of crypto-ransomware that arrive via email or malicious websites.

To get a one-glance comprehensive view of the behavior of this Trojan, refer to the Threat Diagram shown below.

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: 48128 bytes
File Type: DLL
Memory Resident: Yes
Initial Samples Received Date: 25 Mar 2016
Payload: Encrypts files, Overwrites MBR

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.

NOTES:

This ransomware overwrites the affected system's Master Boot Record (MBR). It encrypts the Master File Table (MFT).

It restarts your system and displays a fake CHKDSK:

  SOLUTION

Minimum Scan Engine: 9.800
FIRST VSAPI PATTERN FILE: 12.438.04
FIRST VSAPI PATTERN DATE: 31 Mar 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

Scan your computer with your Trend Micro product to delete files detected as RANSOM_PETYA.D. 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 4

Restore encrypted files from backup.


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