Ruijie Cai

Ruijie Cai


Research Focus & Metrics

Academic Career Length

12Years (2015-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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15 June 2023 in Applied Sciences
Verified
Journal Article
Open access
PDF file
YLYajing Liu
Yajing Liu
RCRuijie Cai
Ruijie Cai
XYXiaokang Yin
Xiaokang Yin
SLShengli Liu
Shengli Liu
As the most crucial link in the network kill chain, exploiting a vulnerability is viewed as one of the most popular attack vectors to get the control authority of the system, which is dangerous for legal users. Therefore, an effective exploit traffic detection method is urgent. However, current methods are almost based on pattern matching, invalid for encrypted traffic. To address this problem, we propose a reverse shell-based exploit traffic detection method, ETDetector. Our key insight is that the reverse shell attack often coexists with vulnerability exploitation as one of the most popular exploit behaviors. So, we first extract the fusion information feature from original features, such as the packet delay sequence, as input of a decision tree model to identify reverse shell traffic in the shellcode execution stage. Then, we trace suspicious traffic in the shellcode delivery stage by reconstructing the session relationship of the two stages above. Compared with Blatta, using a cyclic neural network to detect early exploit traffic, the detection rate of ETDetector is increased by 50% and valid for encrypted exploit traffic. In addition, we propose a traffic stratification method based on a bisecting K-means algorithm, which can intuitively show the traffic communication behavior and improve the interpretability of ETDetector.

4 January 2023 in Applied Sciences
Verified
Journal Article
Open access
PDF file
GGGuoxixi Guo
Guoxixi Guo
RCRuijie Cai
Ruijie Cai
XYXiaokang Yin
Xiaokang Yin
WSWenqiang Shao
Wenqiang Shao
SLShengli Liu
Shengli Liu
Vulnerable open-source component reuse can lead to security problems. At present, open-source component detection for binary programs can only reveal whether open-source components with vulnerabilities are reused, which cannot determine the specific location of vulnerabilities. To address this problem, we propose BMVul, an open-source vulnerability function detection based on the software modularization method, which is oriented to binary programs. BMVul performs binary modularization by the overlapping clustering method DBM based on directed graph, then uses feature comparison technology to carry out modular software component analysis. After creating open-source component vulnerability function set through function signature, BMVul detects vulnerability function in the binary modules reusing open-source components. The experimental results show that compared with the component detection based on Louvain modularization and B2SFinder, BMVul improves the precision by 3.16% and 59.57%, respectively. Moreover, the precision of unique binary module matching is improved by 39.43% compared with the Louvain method. The F1 score is improved by 8.45% compared to B2SFinder. Module-level detection narrows the search space of vulnerability functions, thereby reducing the workload of open-source vulnerability detection, which is of great significance for software security analysis.

3 March 2026 in Cybersecurity
Verified
Journal Article
Open access
PDF file
RCRuijie Cai
Ruijie Cai
XZXiaoya Zhu
Xiaoya Zhu
SLShengli Liu
Shengli Liu
Advanced Persistent Threat (APT) attacks pose significant threats to critical infrastructure security due to their sophisticated techniques and prolonged nature. Effective network traceability and attack source identification are crucial for mitigating these threats. Time-based network flow watermarking has emerged as a promising approach for tracing APT attacks. However, existing time-based methods face limitations, including reliance on predefined temporal parameters that reduce adaptability to diverse traffic patterns, detectability due to absolute inter-packet delay (IPD) extensions, and sensitivity to network timing fluctuations that affect reliability. To address these challenges, we propose ADIPD, an adaptive watermarking scheme that leverages relative temporal relationships. Our core innovation lies in windowed IPD modulation, where traffic is divided into chronologically ordered windows, and watermarks are embedded by regulating the relative differences between average IPDs of strategically positioned sub-windows. Additionally, a delay minimization strategy compresses IPDs in sub-windows with lower average delays, enhancing both stealthiness and robustness. Experimental results demonstrate that ADIPD outperforms classical methods (WBIPD, IBW, ICBW) in robustness, invisibility, and practicality, achieving higher watermark extraction accuracy under temporal interference while requiring fewer packets and shorter embedding times. This work advances network flow watermarking technology by balancing robustness, stealth, and adaptability, offering a scalable solution for tracing sophisticated cyberattacks.