Covert channel networks are a well-known method for circumventing the security measures organizations put in place to protect their networks from adversarial attacks. This paper introduces a novel method based on bit-rate modulation for implementing covert channels between devices connected over a wide area network. This attack can be exploited to exfiltrate sensitive information from a machine (i.e., covert sender) and stealthily transfer it to a covert receiver while evading network security measures and detection systems. We explain how to implement this threat, focusing specifically on covert channel networks and their potential security risks to network information transmission. The proposed method leverages bit-rate modulation, where a high bit rate represents a '1' and a low bit rate represents a '0', enabling covert communication. We analyze the key metrics associated with covert channels, including robustness in the presence of legitimate traffic and other interference, bit-rate capacity, and bit error rate. Experiments demonstrate the good performance of this attack, which achieved 5 bps with excellent robustness and a channel capacity of up to 0.9239 bps/Hz under different noise sources. Therefore, we show that bit-rate modulation effectively violates network security and compromises sensitive data.

翻译：隐蔽信道网络是一种已知的规避组织为保护其网络免受对抗攻击而设置的安全措施的方法。本文提出了一种基于比特率调制的新方法，用于在广域网连接的设备之间实现隐蔽信道。该攻击可用于从机器（即隐蔽发送方）窃取敏感信息，并在规避网络安全措施和检测系统的同时，将其秘密传输至隐蔽接收方。我们阐述了如何实施这一威胁，特别关注隐蔽信道网络及其对网络信息传输的潜在安全风险。所提出的方法利用比特率调制，其中高比特率表示“1”，低比特率表示“0”，从而实现隐蔽通信。我们分析了与隐蔽信道相关的关键指标，包括在合法流量和其他干扰存在下的鲁棒性、比特率容量以及误比特率。实验表明，该攻击性能良好，在多种噪声源下实现了5 bps的速率，且具有优异的鲁棒性，信道容量最高可达0.9239 bps/Hz。因此，我们证明比特率调制能有效破坏网络安全并危及敏感数据。