About SONAR

SONAR is a real-time protection that detects potentially malicious applications when they run on your computers. SONAR provides "zero-day" protection because it detects threats before traditional virus and spyware detection definitions have been created to address the threats.
SONAR uses heuristics as well as reputation data to detect emerging and unknown threats. SONAR provides an additional level of protection on your client computers and complements your existing Virus and Spyware Protection, intrusion prevention, Memory Exploit Mitigation, and firewall protection.
SONAR uses a heuristics system that leverages Symantec's online intelligence network with proactive local monitoring on your client computers to detect emerging threats. SONAR also detects changes or behavior on your client computers that you should monitor.
Auto-Protect also uses a type of heuristic that is called Bloodhound to detect suspicious behavior in files.
SONAR might inject some code into the applications that run in Windows user mode to monitor them for suspicious activity. In some cases, the injection might affect the application performance or cause problems with running the application. You can create an exception to exclude the file, folder, or application from this type of monitoring.
SONAR does not make detections on application type, but on how a process behaves. SONAR acts on an application only if that application behaves maliciously, regardless of its type. For example, if a Trojan horse or keylogger does not act maliciously, SONAR does not detect it.
SONAR detects the following items:
Heuristic threats
SONAR uses heuristics to determine if an unknown file behaves suspiciously and might be a high risk or low risk. It also uses reputation data to determine whether the threat is a high risk or low risk.
System changes
SONAR detects applications or the files that try to modify DNS settings or a host file on a client computer.
Trusted applications that exhibit bad behavior
Some good trusted files might be associated with suspicious behavior. SONAR detects these files as suspicious behavior events. For example, a well-known document sharing application might create executable files.
If you disable Auto-Protect, you limit SONAR's ability to make detections of high and low risk files. If you disable Insight lookups (reputation queries), you also limit the SONAR's detection capability.
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