In one embodiment, a method includes identifying unusual behavior with respect to a handshake between a first endpoint and a second endpoint that are included in a network, and determining whether the unusual behavior with respect to the handshake indicates presence of malicious software. The method also includes identifying at least one of the first endpoint and the second endpoint as potentially being infected by the malicious software if it is determined that the unusual behavior with respect to the handshake indicates the presence of malicious software.