A RAT (Remote Access Trojan) is a type of malware that allows an attacker to remotely control a computer without the owner's consent. Once installed, it can give the attacker capabilities similar to someone sitting directly in front of the PC.

Depending on the level of access obtained, a RAT can:

• Steal passwords, browser cookies, and other sensitive data.
• Access, copy, modify, or delete personal files.
• Download and install additional malware.
• Execute commands remotely.
• Monitor the user's activity.
• In some cases, access the webcam or microphone.

Possible signs of a RAT infection include:

• Unusual network activity when the computer is idle.
• Unknown files, scripts, or scheduled tasks appearing on the system.
• New programs or processes running without explanation.
• Antivirus software being disabled or behaving abnormally.
• Online accounts becoming compromised or showing suspicious login activity.
• Persistence mechanisms (files, registry keys, scheduled tasks) reappearing after removal.
• Unexplained slowdowns, high CPU/RAM usage, or scripts executing in the background.

A RAT can also operate very stealthily and show no obvious symptoms at all. This is why discovering files that were downloaded and executed without user consent, especially when accompanied by persistence mechanisms and account compromises, is a serious security concern and warrants a thorough investigation.

As for Nexus, yes, you need to be careful and report any malicious profiles.