Sundials in the Shade An Internet-Wide Perspective on ICMP Timestamps

• Published in: Passive and Active Measurement pp. 82 - 98
• Main Authors: Rye, Erik C., Beverly, Robert
• Format: Book Chapter
• Language: English
• Published: Cham Springer International Publishing
• Series: Lecture Notes in Computer Science
• Subjects: Fingerprinting; ICMP; Network; Security; Time
• ISBN: 303015985X; 9783030159856
• ISSN: 0302-9743; 1611-3349
• DOI: 10.1007/978-3-030-15986-3_6

ICMP timestamp request and response packets have been standardized for nearly 40 years, but have no modern practical application, having been superseded by NTP. However, ICMP timestamps are not deprecated, suggesting that while hosts must support them, little attention is paid to their implementation and use. In this work, we perform active measurements and find 2.2 million hosts on the Internet responding to ICMP timestamp requests from over 42,500 unique autonomous systems. We develop a methodology to classify timestamp responses, and find 13 distinct classes of behavior. Not only do these behaviors enable a new fingerprinting vector, some behaviors leak important information about the host e.g., OS, kernel version, and local timezone.