Biblio

During an advanced persistent threat (APT), an attacker group usually establish more than one C&C server and these C&C servers will change their domain names and corresponding IP addresses over time to be unseen by anti-virus software or intrusion prevention systems. For this reason, discovering and catching C&C sites becomes a big challenge in information security. Based on our observations and deductions, a malware tends to contain a fixed user agent string, and the connection behaviors generated by a malware is different from that by a benign service or a normal user. This paper proposed a new method comprising filtering and clustering methods to detect C&C servers with a relatively higher coverage rate. The experiments revealed that the proposed method can successfully detect C&C Servers, and the can provide an important clue for detecting APT.

Advanced Persistent Threat (APT), unlike traditional hacking attempts, carries out specific attacks on a specific target to illegally collect information and data from it. These targeted attacks use special-crafted malware and infrequent activity to avoid detection, so that hackers can retain control over target systems unnoticed for long periods of time. In order to detect these stealthy activities, a large-volume of traffic data generated in a period of time has to be analyzed. We proposed a scalable solution, Ctracer to detect stealthy command and control channel in a large-volume of traffic data. APT uses multiple command and control (C&C) channel and change them frequently to avoid detection, but there are common signatures in those C&C sessions. By identifying common network signature, Ctracer is able to group the C&C sessions. Therefore, we can detect an APT and all the C&C session used in an APT attack. The Ctracer is evaluated in a large enterprise for four months, twenty C&C servers, three APT attacks are reported. After investigated by the enterprise's Security Operations Center (SOC), the forensic report shows that there is specific enterprise targeted APT cases and not ever discovered for over 120 days.