Advanced Persistent Threats (APTs) are characterized by their 'Multiphased' nature, referring to the various stages or phases the attacker undertakes to breach a network, remain undetected, and achieve their objectives. This characteristic includes numerous attempts to gain entry to the target's network, often starting with reconnaissance, followed by initial compromise, and progressing through stages such as establishment of a backdoor, expansion, data exfiltration, and maintaining persistence. This multiphased approach allows attackers to adapt and pursue their objectives despite potential disruptions or initial failures in their campaign.References:

"Understanding Advanced Persistent Threats and Complex Malware," by FireEye

MITRE ATT&CK Framework, detailing the multiphased nature of adversary tactics and techniques