  The assessment of cybersecurity Capture-The-Flag (CTF) exercises involves
participants finding text strings or ``flags'' by exploiting system
vulnerabilities. Large Language Models (LLMs) are natural-language models
trained on vast amounts of words to understand and generate text; they can
perform well on many CTF challenges. Such LLMs are freely available to
students. In the context of CTF exercises in the classroom, this raises
concerns about academic integrity. Educators must understand LLMs' capabilities
to modify their teaching to accommodate generative AI assistance. This research
investigates the effectiveness of LLMs, particularly in the realm of CTF
challenges and questions. Here we evaluate three popular LLMs, OpenAI ChatGPT,
Google Bard, and Microsoft Bing. First, we assess the LLMs' question-answering
performance on five Cisco certifications with varying difficulty levels. Next,
we qualitatively study the LLMs' abilities in solving CTF challenges to
understand their limitations. We report on the experience of using the LLMs for
seven test cases in all five types of CTF challenges. In addition, we
demonstrate how jailbreak prompts can bypass and break LLMs' ethical
safeguards. The paper concludes by discussing LLM's impact on CTF exercises and
its implications.
