Reusing off-the-shelf code snippets from online repositories is a common
practice, which significantly enhances the productivity of software developers.
To find desired code snippets, developers resort to code search engines through
natural language queries. Neural code search models are hence behind many such
engines. These models are based on deep learning and gain substantial attention
due to their impressive performance. However, the security aspect of these
models is rarely studied. Particularly, an adversary can inject a backdoor in
neural code search models, which return buggy or even vulnerable code with
security/privacy issues. This may impact the downstream software (e.g., stock
trading systems and autonomous driving) and cause financial loss and/or
life-threatening incidents. In this paper, we demonstrate such attacks are
feasible and can be quite stealthy. By simply modifying one variable/function
name, the attacker can make buggy/vulnerable code rank in the top 11%. Our
attack BADCODE features a special trigger generation and injection procedure,
making the attack more effective and stealthy. The evaluation is conducted on
two neural code search models and the results show our attack outperforms
baselines by 60%. Our user study demonstrates that our attack is more stealthy
than the baseline by two times based on the F1 score.

本文研究了神经代码搜索模型的安全性，在已有的在线代码库中，攻击者可以注入有漏洞的代码片段并使其在搜索结果中排名较高，进而影响到软件系统的正常运行并带来潜在的财务和安全风险。作者提出了一种名为 BADCODE 的攻击方式，并对其进行了测试和评估，结果表明该攻击的成功率比现有的攻击方式高出了 60%。