Time-Deterministic Replay for Covert Timing Channel Detection
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing methods for detecting covert timing channels are ineffective as they rely on pattern recognition, which requires frequent updates to counter new patterns, leading to a cycle of detection and evasion, and fail to accurately reproduce timing variations.
Innovation Solution
The implementation of time-deterministic replay (TDR) systems, such as Sanity, which records and replays the timing of software executions to compare and detect deviations, allowing for the identification of covert timing channels without prior knowledge of encoding schemes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If pattern-based detection methods are used to detect covert timing channels, then detection capability is improved, but the system requires frequent updates to counter new patterns, increasing device complexity and maintenance burden
Solution Approach 1:
The system performs preliminary recording of inputs and timings during normal software execution, storing this data for later replay analysis. This preliminary action enables the detection system to have reference data ready before actual covert channel detection occurs, eliminating the need for frequent pattern updates by establishing a baseline of normal timing behavior
Solution Approach 2:
The system creates a copy of the software execution environment and replays recorded inputs through this copy. By comparing timing outputs from the original execution with the replayed execution, the system can detect covert timing channels without needing to know their patterns in advance, replacing pattern-based detection with behavioral comparison
2Adaptability or versatility
If statistical-based detection methods are used, then detection coverage is improved, but accuracy in detecting low-rate and sporadic covert channels deteriorates
Solution Approach 1:
The system records detailed timing information during preliminary software execution, capturing precise timestamps for each input and output event. This preliminary recording of high-resolution timing data enables accurate detection of even low-rate covert channels by providing a detailed baseline for comparison during replay analysis
Solution Approach 2:
The system compares timing outputs from the original execution with timing outputs from the replayed execution, using this feedback to identify deviations that indicate covert timing channels. The feedback mechanism continuously refines detection accuracy by highlighting timing anomalies that statistical methods would miss
3Measurement precision
If time-deterministic replay is implemented to accurately reproduce timing variations, then detection precision is improved, but computational resources and execution time increase
Solution Approach 1:
The system creates a simplified copy of the original software execution environment for replay purposes. By using a reference copy rather than attempting to perfectly replicate the original environment, the system achieves sufficient timing determinism for detection while reducing the computational overhead and execution time required
Data Source
AI summary
A mechanism called time-deterministic replay (TOR) that can reproduce the execution of a program, including its precise timing. Without TOR, reproducing the timing of an execution is difficult because there are many sources of timing variability. TOR uses a combination of techniques to either mitigate or eliminate most of these sources of variability. Using a prototype implementation of TOR in a Java Virtual Machine, we show it is possible to reproduce the timing to within 1.85% of the original execution. A study of one of the applications of TOR is described: the detection of a covert timing channel. Timing channels can be used to exfiltrate information from a compromised machine by subtly varying timing of the machine's outputs, TOR can detect this variation. Unlike prior solutions, which generally look for a specific type of timing channel, our approach can detect a wide variety of channels with high accuracy.