Fus: Combining Semantic and Structural Graph Information for Binary Code Similarity Detection

Binary code similarity detection (BCSD) plays an important role in software security. Recent deep learning-based methods have made great progress. Existing methods based on a single feature, such as semantics or graph structure, struggle to handle changes caused by the architecture or compilation environment. Methods fusing semantics and graph structure suffer from insufficient learning of the function, resulting in low accuracy and robustness. To address this issue, we proposed Fus, a method that integrates semantic information from the pseudo-C code and structural features from the Abstract Syntax Tree (AST). The pseudo-C code and AST are robust against compilation and architectural changes and can represent the function well. Our approach consists of three steps. First, we preprocess the assembly code to obtain the pseudo-C code and AST for each function. Second, we employ a Siamese network with CodeBERT models to extract semantic embeddings from the pseudo-C code and Tree-Structured Long Short-Term Memory (Tree LSTM) to encode the AST. Finally, function similarity is computed by summing the respective semantic and structural similarities. The evaluation results show that our method outperforms the state-of-the-art methods in most scenarios. Especially in large-scale scenarios, its performance is remarkable. In the vulnerability search task, Fus achieves the highest recall. It demonstrates the accuracy and robustness of our method.