A system including a content server and a plurality of instant messaging clients is configured to enable each client device to scan for malware on incoming or outgoing instant messages. The content server may receive malware configuration information and distribute the malware configuration information to each client device. Each client device may employ the malware configuration information to perform a number of actions, including determining one or more malware scanners to use, selectively scanning incoming or outgoing instant messages, reporting instances of malware that are detected, or selectively restricting one or more instant messaging functions. The system may include a malware information repository that receives and reports of detected malware, analyzes the reports, and determines sources of malware.