A system may determine to perform an internal and an external malware detection operation to detect a malware infection associated with a client device. The system may perform the internal operation by modifying an environment, executing on a particular device, to form a modified environment. The system may perform the external operation by performing a communication from the particular device. The system may monitor the modified environment for a first behavior indicative of the malware infection, and may monitor a result of performing the communication for a second behavior indicative of the malware infection. The system may detect that the first or second behavior has occurred. The system may provide a notification that the client device is infected with malware based on detecting that the first or second behavior has occurred. The notification may cause one or more network devices to block network traffic to or from the client device.