A computer-implemented method for detecting malicious use of digital certificates may include determining that a digital certificate is invalid. The method may further include locating, within the invalid digital certificate, at least one field that was previously identified as being useful in distinguishing malicious use of invalid certificates from benign use of invalid certificates. The method may also include determining, based on analysis of information from the field of the invalid digital certificate, that the invalid digital certificate is potentially being used to facilitate malicious communications. The method may additionally include performing a security action in response to determining that the invalid digital certificate is potentially being used to facilitate malicious communications. Various other methods, systems, and computer-readable media are disclosed.