Malware attacks are increasingly popular attack vectors in online crime. As trends and anecdotal evidence show, preventing these attacks, regardless of their opportunistic or targeted nature, has proven difficult: intrusions happen and devices get compromised, even at securityconscious organisations. As a consequence, an alternative line of work has focused on detecting and disrupting the individual steps that follow an initial compromise and that are essential for the successful progression of the attack. In particular, a number of approaches and techniques have been proposed to identify the Command & Control (C2) channel that a compromised system establishes to communicate with its controller. The success of C2 detection approaches depends on collecting relevant network traffic. As traffic volumes increase this is proving increasingly difficult. In this paper, we analyse current approaches of ISP-scale network measurement from the perspective of C2 detection. We discuss a number of weaknesses that affect current techniques and provide suggestions for their improvement.