The 'Classes Autorun Keys Modification' detection rule identifies unauthorized modifications to the Windows registry specifically targeting autostart extensibility points (ASEP). It monitors changes within specified registry paths that pertain to user associations with file types and shell extensions, which are common avenues for persistence mechanisms utilized by malware. The rule captures registry modifications involving CLSIDs and file associations that allow certain actions or programs to run automatically when file types or folder behaviors are triggered. It utilizes a combination of selection criteria to ensure that any change is legitimate and not one that might arise during normal operations, such as legitimate installations or administrative changes. False positives can occur when legitimate software alters registry keys for valid reasons, hence the importance of careful consideration when analyzing alerts generated by this rule. This detection contributes significantly to identifying potential persistence mechanisms used by attackers after gaining initial access to a system.