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Discovered: November 14, 2019
Updated: November 14, 2019 2:15:04 PM
Type: Trojan
Systems Affected: Windows

POL.B.PECCertutil indicates the blocking of an attempt by the Windows utility Certutil to create a portable executable file on the local disk. This is an advanced attack technique used by attackers to evade traditional intrusion detection systems.

Antivirus Protection Dates

  • Initial Rapid Release version November 14, 2019 revision 007
  • Latest Rapid Release version November 14, 2019 revision 007
  • Initial Daily Certified version November 14, 2019
  • Latest Daily Certified version November 14, 2019
  • Initial Weekly Certified release date November 20, 2019

Click here for a more detailed description of Rapid Release and Daily Certified virus definitions.

Technical Description

POL.B.PECCertutil indicates the blocking of an attempt by the Windows utility Certutil to create a portable executable file on the local disk. This is an advanced attack technique used by attackers to evade traditional intrusion detection systems by moving away from simply downloading malicious payloads over normal network traffic.

Certutil is a Microsoft tool that is intended to be used to maintain and verify certificate authority data. It can be used to fetch remote data.

Typical Attack Scenario
In a typical attack blocked by this detection, attackers may try to entice users to open an Office document that contains a macro. When the document is opened, a macro may run and send commands to Certutil. Certutil in turn attempts to download a malicious payload and run it. Using commonly found and legitimate tools to help carry out attacks is part of a technique known as living off the land.

MITRE ATT&CK Framework
This detection relates to the following MITRE ATT&CK Framework categories:

  • Defense Evasion: Deobfuscate/Decode Files or Information (T1140)

Files that are blocked by this behavioral detection are considered malicious. If you have reason to believe that your files are incorrectly detected by Symantec products, you can submit them to Symantec Security Response for further analysis.


Symantec Security Response encourages all users and administrators to adhere to the following basic security "best practices":

  • Use a firewall to block all incoming connections from the Internet to services that should not be publicly available. By default, you should deny all incoming connections and only allow services you explicitly want to offer to the outside world.
  • Enforce a password policy. Complex passwords make it difficult to crack password files on compromised computers. This helps to prevent or limit damage when a computer is compromised.
  • Ensure that programs and users of the computer use the lowest level of privileges necessary to complete a task. When prompted for a root or UAC password, ensure that the program asking for administration-level access is a legitimate application.
  • Disable AutoPlay to prevent the automatic launching of executable files on network and removable drives, and disconnect the drives when not required. If write access is not required, enable read-only mode if the option is available.
  • Turn off file sharing if not needed. If file sharing is required, use ACLs and password protection to limit access. Disable anonymous access to shared folders. Grant access only to user accounts with strong passwords to folders that must be shared.
  • Turn off and remove unnecessary services. By default, many operating systems install auxiliary services that are not critical. These services are avenues of attack. If they are removed, threats have less avenues of attack.
  • If a threat exploits one or more network services, disable, or block access to, those services until a patch is applied.
  • Always keep your patch levels up-to-date, especially on computers that host public services and are accessible through the firewall, such as HTTP, FTP, mail, and DNS services.
  • Configure your email server to block or remove email that contains file attachments that are commonly used to spread threats, such as .vbs, .bat, .exe, .pif and .scr files.
  • Isolate compromised computers quickly to prevent threats from spreading further. Perform a forensic analysis and restore the computers using trusted media.
  • Train employees not to open attachments unless they are expecting them. Also, do not execute software that is downloaded from the Internet unless it has been scanned for viruses. Simply visiting a compromised Web site can cause infection if certain browser vulnerabilities are not patched.
  • If Bluetooth is not required for mobile devices, it should be turned off. If you require its use, ensure that the device's visibility is set to "Hidden" so that it cannot be scanned by other Bluetooth devices. If device pairing must be used, ensure that all devices are set to "Unauthorized", requiring authorization for each connection request. Do not accept applications that are unsigned or sent from unknown sources.
  • For further information on the terms used in this document, please refer to the Security Response glossary.