This detection rule monitors for suspicious executions of the Rundll32.exe process, specifically when it is called with DLL files that are disguised as image file types. Such tactics are often employed by attackers to evade defenses by using common file extensions (.bmp, .jpg, .png, etc.) that are generally considered safe. The rule leverages two sets of selection criteria: it first determines if the process being executed is Rundll32.exe and then checks if the command line arguments include image file extensions. A match across both criteria suggests possible malicious intent, triggering an alert for further investigation. This behavior can be linked to various attack techniques, especially around defense evasion and malware distribution, as highlighted in industry research.