Evaluating Large Language Models for Deobfuscating Malicious PowerShell Scripts in Real-World Malware Campaigns

Core Concepts

Large language models can effectively automate a substantial portion of the malware deobfuscation process, with state-of-the-art models exhibiting promising capabilities in processing and understanding obfuscated code, though challenges remain in minimizing hallucinations and expanding input size.

Abstract

The article explores the potential of using large language models (LLMs) for deobfuscating malicious PowerShell scripts used in real-world malware campaigns, specifically the notorious Emotet malware. The authors conducted experiments using four state-of-the-art LLMs, including cloud-based models from OpenAI and Google, as well as locally deployed models from Meta and Mistral AI. The key findings are: OpenAI's GPT-4 outperformed the other LLMs, correctly identifying 69.56% of the URLs in the obfuscated scripts. Google's Gemini Pro achieved 36.84% accuracy, while the local models, Code Llama and Mixtral, scored 22.13% and 11.59%, respectively. Relaxing the task to extract the correct domain instead of the full URL significantly improved the accuracy, with GPT-4 reaching 88.78% and the other models also seeing substantial boosts. The local LLMs exhibited a higher rate of hallucinations, with Mixtral generating the most, nearly 70% more than Code Llama. The hallucinated domains often resembled patterns found in the training data, indicating the models' attempts to fill in the gaps. The cloud-based models, GPT-4 and Gemini Pro, occasionally refused to perform the task, citing ethical concerns about processing potentially malicious code. The authors conclude that while LLMs are not yet mature enough to fully replace traditional deobfuscators, they can effectively complement them in existing pipelines, especially during malware campaigns where threat actors frequently change their droppers and payloads. The article also discusses key areas for improvement, such as minimizing hallucinations, expanding input size, and enhancing training methodologies to better handle obfuscated code.

Stats

"The dataset contains 2,000 unique obfuscated PowerShell scripts used as droppers for the Emotet malware campaign, which refer to 2,869 unique URLs belonging to 2,512 unique domains." "On average, each script contains 6.6 URLs from different domains."

Quotes

"While theoretically, packers and cryptors are different, most modern packers come with some encryption scheme." "Malware authors are well aware of this. Thus, during a malware campaign, the payload, obfuscation mechanisms, and packers can change, leading to the loss of crucial information or requiring a lot of manual effort to alleviate this." "LLMs have elevated natural language processing (NLP) capabilities, enabling more refined and context-aware text interpretations and producing coherent and contextually relevant responses, leveraging human-computer interactions."

Key Insights Distilled From

Assessing LLMs in Malicious Code Deobfuscation of Real-world Malware Campaigns

by Constantinos... at arxiv.org 05-01-2024

https://arxiv.org/pdf/2404.19715.pdf

Deeper Inquiries

How can the training of LLMs be improved to better handle obfuscated code and minimize hallucinations?

Training LLMs to better handle obfuscated code and minimize hallucinations involves several key strategies: Diverse and Representative Training Data: To improve LLMs' performance in deobfuscating code, the training data should include a wide variety of obfuscated code samples from different sources and obfuscation techniques. This diverse dataset will help the model learn to generalize better and handle various forms of obfuscation. Fine-Tuning on Obfuscated Code: LLMs can be fine-tuned specifically on obfuscated code to improve their understanding of such patterns. By training the model on a large corpus of obfuscated code, it can learn the specific features and structures associated with obfuscation. Prompt Engineering: Crafting effective prompts that guide the LLMs to focus on specific aspects of the code can help reduce hallucinations. Clear and detailed prompts can steer the model towards the intended task and minimize irrelevant outputs. Feedback Mechanisms: Implementing feedback mechanisms where the model receives corrections or guidance on its outputs can help refine its understanding of obfuscated code over time. This iterative process can help the model learn from its mistakes and improve its performance. Regular Evaluation and Validation: Continuously evaluating the model's performance on a diverse set of obfuscated code samples and validating the results against ground truth can help identify areas of improvement and guide further training iterations. Collaborative Research and Benchmarking: Collaborating with the cybersecurity community to create standardized benchmarks and evaluation metrics for LLMs in handling obfuscated code can drive research efforts towards more effective solutions. Sharing best practices and insights can benefit the entire research community.

How can LLMs be integrated with traditional malware analysis tools to create a more comprehensive and adaptive threat intelligence pipeline?

Integrating LLMs with traditional malware analysis tools can enhance threat intelligence pipelines in several ways: Automated Deobfuscation: LLMs can be used to automatically deobfuscate malicious code, providing insights into the functionality and behavior of malware. By integrating LLMs into the analysis pipeline, analysts can quickly extract actionable intelligence from obfuscated code. Contextual Understanding: LLMs excel at understanding context and generating human-like responses. By incorporating LLMs into the pipeline, analysts can leverage their capabilities to interpret complex code structures, identify patterns, and extract relevant information for threat analysis. Adaptive Rule Generation: LLMs can assist in generating adaptive detection rules based on the deobfuscated code. By analyzing the output of LLMs, analysts can create dynamic rules to detect new malware variants and threats, enhancing the pipeline's adaptability to evolving threats. MITRE ATT&CK Mapping: LLMs can be used to map deobfuscated code to MITRE ATT&CK techniques, providing a standardized framework for understanding and categorizing malicious behavior. This mapping can help analysts correlate malware samples with known attack patterns and tactics. Real-time Analysis: By integrating LLMs into the pipeline, analysts can perform real-time analysis of obfuscated code, enabling faster detection and response to emerging threats. LLMs can assist in triaging alerts, identifying indicators of compromise, and extracting IOCs for further investigation. Continuous Improvement: Regularly updating and fine-tuning LLMs based on feedback from the analysis pipeline can enhance their performance and accuracy in handling malware analysis tasks. This iterative process of improvement ensures that the pipeline remains effective against evolving threats.

What are the potential ethical and legal implications of using LLMs for malware analysis, and how can these be addressed?

The use of LLMs for malware analysis raises several ethical and legal considerations that need to be addressed: Privacy and Data Protection: LLMs may process sensitive information during malware analysis, raising concerns about data privacy and protection. It is essential to ensure that data handling complies with relevant regulations such as GDPR and that personal or confidential information is handled securely. Bias and Fairness: LLMs can exhibit biases based on the training data they are exposed to, potentially leading to discriminatory outcomes. To address this, it is crucial to regularly audit and mitigate biases in the models and ensure fairness in the analysis results. Transparency and Accountability: The decisions made by LLMs in malware analysis should be transparent and explainable. Establishing clear accountability mechanisms for the actions taken based on LLM outputs is essential to maintain trust and integrity in the analysis process. Security Risks: LLMs themselves can be vulnerable to adversarial attacks, where malicious actors manipulate the model's outputs to evade detection or mislead analysts. Implementing robust security measures to protect LLMs from such attacks is critical for maintaining the integrity of the analysis pipeline. Regulatory Compliance: Compliance with relevant cybersecurity laws and regulations is paramount when using LLMs for malware analysis. Organizations must ensure that their use of LLMs aligns with legal requirements and industry standards to avoid potential legal repercussions. Informed Consent: When LLMs are used to analyze potentially harmful or malicious content, obtaining informed consent from stakeholders, such as users whose data is being analyzed, is crucial. Transparency about the use of LLMs in malware analysis and the potential implications of their findings is essential for ethical practice. Addressing these ethical and legal implications requires a multi-faceted approach, including robust data governance practices, bias mitigation strategies, transparency in model deployment, and adherence to regulatory frameworks governing cybersecurity and data protection. Collaboration between cybersecurity experts, legal professionals, and ethicists is essential to navigate these complex issues effectively.