Disclosed are various embodiments for malware detection by way of proxy servers. In one embodiment, a proxied request for a network resource from a network site is received from a client device by a proxy server application. The proxied request is analyzed to determine whether the proxied request includes protected information transmitted in an unsecured manner. It is then determined whether the network resource comprises malware based at least in part on an execution of the network resource or whether the proxied request includes the protected information transmitted in the unsecured manner. The proxy server application refrains from sending data generated by the network resource to the client device in response to the proxied request when the network resource is determined to comprise the malware.