The IDPS must detect, at a minimum, mobile code that is unsigned or exhibiting unusual behavior, has not undergone a risk assessment, or is prohibited for use based on a risk assessment.

Mobile code is defined as software modules obtained from remote systems, transferred across a network, and then downloaded and executed on a local system without explicit installation or execution by the recipient. Examples of mobile code include JavaScript, VBScript, Java applets, ActiveX controls, Flash animations, Shockwave videos, and macros embedded within Microsoft Office documents. Mobile code can be exploited to attack a host. It can be sent as an e-mail attachment or embedded in other file formats not traditionally associated with executable code.

While the IDPS cannot replace the anti-virus and host-based IDS (HIDS) protection installed on the network's endpoints, vendor or locally created sensor rules can be implemented, which provide preemptive defense against both known and zero-day vulnerabilities. Many of the protections may provide defenses before vulnerabilities are discovered and rules or blacklist updates are distributed by anti-virus or malicious code solution vendors.

To monitor for and detect known prohibited mobile code or approved mobile code that violates permitted usage requirements, the IDPS must implement policy filters, rules, signatures, and anomaly analysis.