PhD students Younghwan Go, Shinae Woo (advisor : KyoungSoo Park), Prof. KyoungSoo Park and Yongdae Kim received BEST PAPER AWARD from The 5th Annual Wireless of the Students, by the Students, for the Students Workshop (ACM S3 2013) on Septermber 30 2013 with paper titled “Impact of Malicious TCP Retransmission on Cellular Traffic Accounting”
Current cellular network architecture charges users based on the consumed IP traffic in byte-level. While the users receive payload at the application layer, there exists a transport layer (TCP) that can cause additional data consumption due to the retransmission that guarantees a reliable delivery. In this paper, we examine the accounting policies regarding the TCP’s retransmission in five major cellular ISPs in the U.S. and South Korea and show that the current implementation is either vulnerable to billing inflation or allows the subscribers to bypass the charging. Two ISPs account for all retransmission packets, allowing attackers to inflate a victim’s bill by intentionally retransmitting packets. Three ISPs exclude the retransmission packets from the user’s bill thus allowing tunneling through TCP retransmissions. We present real-world attack scenarios where “usage-inflation” and “free-riding” attacks are plausible.