Direct system calls refer to the technique where software, often malware, interacts directly with the operating system kernel by invoking system calls without using standard APIs or libraries. This approach allows malicious programs to bypass user-mode security tools, monitoring solutions, and endpoint protection software, making detection and analysis more difficult. By avoiding the typical user-mode hooks and security checks, attackers can execute privileged operations, manipulate system resources, or hide their activities more effectively. Security professionals monitor for direct system calls as they are a common technique in advanced persistent threats (APTs) and sophisticated malware campaigns. Understanding and detecting such behavior is crucial for robust cybersecurity defense.