Analysis by: RonJay Kristoffer Caragay
ALIASES:

Trojan:Win32/Anaki.A (Microsoft); RDN/Ransom!ek (McAfee); Trojan.Cryptodefense (Symantec); Trojan-Ransom.Win32.Blocker.ftvc (Kaspersky); Trojan-Ransom.Win32.Blocker (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

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 deletes itself after execution.

  TECHNICAL DETAILS

File Size: 191,488 bytes
Initial Samples Received Date: 25 Sep 2014

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.

Installation

This Trojan drops the following copies of itself into the affected system:

  • %System Root%\{random filename 1}\{random filename 1}.exe
  • %Application Data%\{random filename 1}.exe
  • %User Startup%\{random filename 1}.exe

(Note: %System Root% is the root folder, which is usually C:\. It is also where the operating system is located.. %Application Data% is the current user's Application Data folder, which is usually C:\Documents and Settings\{user name}\Application Data on Windows 2000, XP, and Server 2003, or C:\Users\{user name}\AppData\Roaming on Windows Vista and 7.. %User Startup% is the current user's Startup folder, which is usually C:\Windows\Profiles\{user name}\Start Menu\Programs\Startup on Windows 98 and ME, C:\WINNT\Profiles\{user name}\Start Menu\Programs\Startup on Windows NT, and C:\Documents and Settings\{User name}\Start Menu\Programs\Startup.)

It drops the following files:

  • %User Startup%\DECRYPT_INSTRUCTION.TXT
  • %User Startup%\DECRYPT_INSTRUCTION.HTML
  • %User Startup%\DECRYPT_INSTRUCTION.URL
  • %Desktop%\DECRYPT_INSTRUCTION.TXT
  • %Desktop%\DECRYPT_INSTRUCTION.HTML
  • %Desktop%\DECRYPT_INSTRUCTION.URL

(Note: %User Startup% is the current user's Startup folder, which is usually C:\Windows\Profiles\{user name}\Start Menu\Programs\Startup on Windows 98 and ME, C:\WINNT\Profiles\{user name}\Start Menu\Programs\Startup on Windows NT, and C:\Documents and Settings\{User name}\Start Menu\Programs\Startup.. %Desktop% is the current user's desktop, which is usually C:\Documents and Settings\{User Name}\Desktop on Windows 2000, XP, and Server 2003, or C:\Users\{user name}\Desktop on Windows Vista and 7.)

Autostart Technique

This Trojan adds the following registry entries to enable its automatic execution at every system startup:

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
{random key} = "%System Root%\{random filename 1}\{random filename 1}.exe"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
{random filename 1} = "%Application Data%\{random filename 1}.exe"

Other System Modifications

This Trojan adds the following registry keys:

HKEY_CURRENT_USER\Software\{UID}

HKEY_CURRENT_USER\Software\{UID}\
{random key}

It adds the following registry entries:

HKEY_CURRENT_USER\Software\{UID}\
{random key}
{Path and File name of encrypted file} = "{hex values}"

It modifies the following registry entries:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows NT\CurrentVersion\SystemRestore
DisableSR = "1"

(Note: The default value data of the said registry entry is 0.)

Other Details

This Trojan connects to the following possibly malicious URL:

  • http://{BLOCKED}ntin.com/{random}
  • http://{BLOCKED}y.com/{random}
  • http://{BLOCKED}nih.com/{random}
  • http://{BLOCKED}tsp.com/{random}
  • http://{BLOCKED}poster.com/{random}

It deletes itself after execution.

NOTES:

This Trojan drops the following files in every folder after encryption:

  • DECRYPT_INSTRUCTION.HTML
  • DECRYPT_INSTRUCTION.TXT
  • DECRYPT_INSTRUCTION.URL