We analyzed the generation of protocol header fields in the implementations of multiple TCP/IP network stacks and found new ways to leak information about global protocol states. We then demonstrated new covert channels by remotely observing and modifying the system's global state via these protocol fields. Unlike earlier works, our research focuses on hosts that reside in firewalled networks (including source address validation – SAV), which is a very common scenario nowadays. Our attacks are designed to be non-disruptive – in the exfiltration scenario, this makes the attacks stealthier and thus extends their longevity, and in case of host alias resolution and similar techniques – this ensures the techniques are ethical. We focused on ICMP, which is commonly served by firewalls, and on UDP, which is forecasted to take a more prominent share of the Internet traffic with the advent of HTTP/3 and QUIC, though we report results for TCP as well.

The information leakage scenarios we discovered enable the construction of practical covert channels which directly pierce firewalls, or indirectly establish communication via hosts in firewalled networks that also employ SAV. We describe and test
three novel attacks in this context: exfiltration via the firewall itself, exfiltration via a DMZ host, and exfiltration via co-resident
containers. These are three generic, new use cases for covert channels that work around firewalling and enable devices that
are not allowed direct communication with the Internet, to still exfiltrate data out of the network. In other words, we exfiltrate
data from isolated networks to the Internet. We also explain how to mount known attacks such as host alias resolution, de-NATting
and container co-residence detection, using the new information leakage techniques.

View More Papers

ATTEQ-NN: Attention-based QoE-aware Evasive Backdoor Attacks

Xueluan Gong (Wuhan University), Yanjiao Chen (Zhejiang University), Jianshuo Dong (Wuhan University), Qian Wang (Wuhan University)

Read More

Let’s Authenticate: Automated Certificates for User Authentication

James Conners (Brigham Young University), Corey Devenport (Brigham Young University), Stephen Derbidge (Brigham Young University), Natalie Farnsworth (Brigham Young University),...

Read More

P4DDPI: Securing P4-Programmable Data Plane Networks via DNS Deep...

Ali AlSabeh (University of South Carolina), Elie Kfoury (University of South Carolina), Jorge Crichigno (University of South Carolina) and Elias...

Read More

HeadStart: Efficiently Verifiable and Low-Latency Participatory Randomness Generation at...

Hsun Lee (National Taiwan University), Yuming Hsu (National Taiwan University), Jing-Jie Wang (National Taiwan University), Hao Cheng Yang (National Taiwan...

Read More