An advanced persistent threat (APT) is a covert (71) attack on a computer networkwhere the attacker gains and maintains (72)access to the targeted network and remains undetected for a significant period. An APT is a sophisticated,long-term and (73) attack,usually orchestrated by nation-state groups，or well-organized criminal enterprises. Duringthe time between infection and remediation the hacker will often monitor，intercept，and relayinformation and sensitive data. The intention of an APT is usually to (74) or steal datarather than cause a network outage，denial of service or infect systems with malware.APTsoften use social engineering tactics or exploit security (75)in networks，applications orfiles to plant malware on target systems.A successful advanced persistent threat can beextremely effective and beneficial to the attacker.

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