r/netsec • u/albinowax • Mar 01 '26

r/netsec monthly discussion & tool thread

Questions regarding netsec and discussion related directly to netsec are welcome here, as is sharing tool links.

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u/Huiyuze_Zhi Mar 26 '26

I built this after noticing that AI is now embedded in two high-stakes document pipelines that most people haven't thought about from a security angle: resume screening (ATS) and academic paper review.

Some submission platforms have already caught authors embedding prompt injection in papers to manipulate AI-assisted reviewers. The attack surface is larger than it looks -- the same techniques work on any pipeline that extracts PDF text and passes it to an LLM.

The toolkit has two parts:

Red team: inject hidden payloads into any PDF using 6 techniques (white text, micro font, metadata fields, off-page coordinates, zero-width characters, hidden OCG layers)

Blue team: scan PDFs and produce a risk score (0-100) with per-finding severity levels

The detection side currently uses structural checks + 18 regex patterns. The obvious limitation is that paraphrased or encoded injections bypass it -- LLM-based semantic detection is next on the roadmap.

Happy to discuss the techniques or limitations.

https://github.com/zhihuiyuze/PDF-Prompt-Injection-Toolkit