Why do attackers use legitimate remote-access tools?
Because they are trusted. Remote-support and remote-management tools are signed, commonly installed and allowed through firewalls, so antivirus rarely flags them, and their traffic goes to the vendor's cloud like every legitimate session. Attackers install them after getting in, or abuse ones already present, to keep access that survives a password change. CISA's advisories on groups such as Akira and Medusa describe exactly this use of remote-access software. Keep a list of the tools your company actually uses, block the installation of others, require multi-factor authentication (MFA) on the ones you allow, and remove those nobody needs. On the network, an unexpected tool shows up as a host connecting regularly to a remote-access vendor it never used before. NetSenX flags such new regular check-ins as beaconing on every plan; deciding whether a tool is approved is up to you.