> Viruses & Risks > Ransom.CTBLocker


Risk Level 1: Very Low

July 16, 2014
August 30, 2016 11:39:56 AM
Also Known As:
Trojan-Ransom.Win32.Onion [Kaspersky], Win32/Critroni.A [Microsoft], TROJ_CRYPCTB.A [Trend], Trojan.Cryptolocker.G [Symantec]
Systems Affected:
Windows 2000, Windows 7, Windows 95, Windows 98, Windows Me, Windows NT, Windows Server 2003, Windows Server 2008, Windows Vista, Windows XP
Ransom.CTBLocker is a Trojan horse that encrypts files on the compromised computer and then prompts the user to purchase a password in order to decrypt them.

Note: Definitions prior to August, 2016 may detect this threat as Trojan.Cryptolocker.G

For more information, see our blog:
The dawn of ransomwear: How ransomware could move to wearable devices

Antivirus Protection Dates

  • Initial Rapid Release version July 16, 2014 revision 006
  • Latest Rapid Release version October 24, 2016 revision 007
  • Initial Daily Certified version July 16, 2014 revision 016
  • Latest Daily Certified version October 24, 2016 revision 021
  • Initial Weekly Certified release date July 16, 2014
Click here for a more detailed description of Rapid Release and Daily Certified virus definitions.

Threat Assessment


  • Wild Level: Low
  • Number of Infections: 0 - 49
  • Number of Sites: 0 - 2
  • Geographical Distribution: Low
  • Threat Containment: Easy
  • Removal: Easy


  • Damage Level: Medium
  • Payload: Demands a ransom to decrypt files on the compromised computer.
  • Modifies Files: Encrypts files on the compromised computer.


  • Distribution Level: Low
Writeup By: Mark Anthony Balanza

Search Threats

Search by name

Example: W32.Beagle.AG@mm