Mex+Sync: Software Covert Channels Exploiting Mutual Exclusion and Synchronization

• Published in: IEEE transactions on computer-aided design of integrated circuits and systems Vol. 42; no. 12; p. 1
• Main Authors: Zhang, Jiliang, Shen, Chaoqun, Qu, Gang
• Format: Journal Article
• Language: English
• Published: New York IEEE 01-12-2023; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Bit error rate; Channels; Covert Channel; Hardware; Linux; Mutual Exclusion; Process control; Process management; Software; Synchronism; Synchronization; Time measurement; Trojan horses; Virtual environments
• ISSN: 0278-0070; 1937-4151
• DOI: 10.1109/TCAD.2023.3291669

The Mutual Exclusion and Synchronization Mechanism (MESM) is a basic process management mechanism in modern operating systems. However, we first found that MESM has serious vulnerabilities. In this paper, a new set of MESM-based software covert channels, named Mex+Sync, are proposed to transmit confidential information. Mex+Sync offer several advantages: 1) the covert channels are constructed at the software level and can be deployed on any hardware; 2) the closed shared resource ensures the quality of the channels with low interference and makes them hard to be detected; and 3) the attack utilizes the system's software resources which abound and hence difficult to isolate. We build the covert channels on Linux and Windows with the following MESMs: flock, FileLockEX, Mutex, Semaphore, Event and WaitableTimer. Experimental results demonstrate that these covert channels can achieve transmission rate of 13.105 kb/s, 12.383 kb/s, and 6.552 kb/s, respectively, in the scenarios of local, cross-sandbox and cross-virtual machine, all with bit error rate under 1%. Meanwhile, we carefully analyze and verify the impact of noise on channel performance.