Towards accurate accounting of cellular data for TCP retransmission

Abstract

The current architecture supporting data services to mobile devices is built below the network layer (IP) and users receive the payload at the application layer. Between them is the transport layer that can cause data consumption inflation due to the retransmission mechanism that provides reliable delivery. In this paper, we examine the accounting policies of five large cellular ISPs in the U.S. and South Korea. We look at their policies regarding the transport layer reliability mechanism with TCP's retransmission and show that the current implementation of accounting policies either fails to meet the billing fairness or is vulnerable to charge evasions. Three of the ISPs surveyed charge for all IP packets regardless of retransmission, allowing attackers to inflate a victim's bill by intentionally retransmitting packets. The other two ISPs deduct the retransmitted amount from the user's bill thus allowing tunneling through TCP retransmissions. We show that a "free-riding" attack is viable with these ISPs and discuss some of the mitigation techniques.

Unveiling the hidden dangers of public IP addresses in 4G/LTE cellular data networks

“…Go et al highlighted that flawed accounting policies in the cellular ISP's in USA and South Korea can result in subscribers being wrongly charged for retransmitted TCP packets [5], and this vulnerability in the ISP's accounting mechanism can be exploited by adversaries to inflate the subscriber's bill by sending unnecessary retransmissions. Similarly, Kang et al discussed how an attacker with a cellular device can spoof the IP address of another subscriber in the same local network and send request packets to Internet servers [9].…”

“…They will be counted towards the subscriber's data quota. Go et al briefly mentioned the possibility of such an attack when they examined how subscribers can be overcharged by TCP retransmissions [5]. Because of the billing structure of mobile ISPs, an attacker can simply flood the victim with random packets at a very high rate, and the victim will have to pay for all the packets, even if they do not eventually reach the victim's device.…”

“…In recent years, significant amount of research efforts have been focused to demonstrate such attacks which particularly include over-billing attacks [5], battery depletion attacks [15,16], Denial of Service (DoS) attacks [8,17,19], IP spoofing and masquerading attacks [12].…”

Dynamic adaptation of the jitter buffer for video streaming applications

“…WiFi networks may have data loss rate up to 4-5 % in dynamically moving environment. Mobile data networks has less data loss rates, but still high enough to introduce decrease of live video stream QoS [8], [9].…”

Real Threats to Your Data Bills

“…To prevent unauthorized access, cellular operators also deploy firewalls and network address translators (NATs) to shield mobile devices from the traffic types of no interest. While recent studies [21,22,27,28,36] have reported various cases on accounting volume inaccuracy, the two aspects of authentication and authorization still look bullet-proof. They seem almost impossible to go wrong.…”