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  3. Ransom.Cryptolocker


Risk Level 1: Very Low

September 11, 2013
August 26, 2016 11:44:45 AM
Also Known As:
Trojan.Gpcoder.H [Symantec], CryptLocker.B [Norman], Trojan:Win32/Crilock.A [Microsoft], TROJ_CRILOCK.NS [Trend], Trojan.Ransomcrypt.F [Symantec], Trojan.Cryptolocker [Symantec]
Infection Length:
346,112 bytes
Systems Affected:
Ransom.Cryptolocker 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.

  • Definitions prior to August, 2016 may detect this threat as Trojan.Cryptolocker
  • Virus definitions dated 11/13/2013 or earlier may detect this threat as Trojan.Ransomcrypt.F
  • Virus definitions dated 09/13/2013 or earlier may detect this threat as Trojan.Gpcoder.H

For more information, please see the following resources:

Antivirus Protection Dates

  • Initial Rapid Release version September 11, 2013 revision 022
  • Latest Rapid Release version May 28, 2017 revision 004
  • Initial Daily Certified version September 12, 2013 revision 001
  • Latest Daily Certified version May 28, 2017 revision 002
  • Initial Weekly Certified release date September 18, 2013
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: Nino Fred P Gutierrez

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STAR Antimalware Protection Technologies
2016 Internet Security Threat Report, Volume 21