PAK_Generic is the Trend Micro detection for possibly malicious executable files that are compressed using Win32 compression tools. This proactive detection also includes appending viruses found in the wild. It is a heuristic detection based on well-established characteristics inherent to compressed malware.
To keep you a step ahead from possible malware infections, all executable files found in the system that match established characteristics are immediately detected.

Not necessarily. Packing is a technique used to reduce the file size and protect the binaries of PE files. It has legitimate uses but it is used by malware authors as well.

IntelliTrap is the Trend Micro heuristic technology used to discover threats that use realtime compression paired with other malware characteristics like Packers.

• OfficeScan
  To access this feature, navigate to Agents > Agent Management > Select Domain > Scan Settings > Real-time Scan Settings > Target tab > Virus/Malware Scan Settings Only > Enable IntelliTrap.
  

  

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• Deep Security
  To access this feature, navigate to Policies > Malware Scan Configurations > Select your Real-time Scan Configuration > General tab > IntelliTrap.
  

  

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• Worry Free Business Security Standard/Advanced
  To access this feature, navigate to Devices > Select Group > Configure Policy > Antivirus/Antispyware > Advanced Settings > Enable IntelliTrap.
  

  

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• Worry Free Business Security Services
  To access this feature, navigate to Security Agents > Select Group > Configure Policy > Scan Settings > Real-time Scan > Configure Settings > Advanced Settings > Enable IntelliTrap.

  

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These files should be submitted to Trend Micro for analysis. Once verified to be non-malicious, they will be added to the next IntelliTrap Exception Pattern.
While waiting for the pattern to be released, you can add the files to the real-time scan exception list in the product to prevent detection.