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I ran a paid bug-bounty-style game against my own multimodal prompt firewall, it didn't make money, so here's the code, the model and 13k real bypass attempts

0
Medium
Published: 07/22/2026 (07/22/2026, 18:11:03 UTC)
Source: Reddit NetSec

Description

This report describes a paid bug-bounty-style game conducted against a multimodal prompt firewall designed to detect prompt injection and jailbreak attempts targeting large language models (LLMs). The project includes open-source code, a fine-tuned DeBERTa-v3-large binary classifier model, and a dataset of 13,230 real-world attack attempts collected over a year. The detector uses a two-stage approach combining regex pattern matching and machine learning inference to filter malicious inputs across multiple modalities including text, images, documents, and audio. The dataset and tooling are intended as a mitigation layer rather than a complete solution, and the author encourages further testing and improvement. No direct vulnerability or exploit is reported, and no patch or fix is applicable as this is a defensive research artifact.

Reddit Discussion

r/netsec·posted by u/BordairAPI
00

Quick bit of context for why this dataset exists. I spent the best part of a year on a startup where the product was an AI guard sitting in front of an LLM, and the pitch to users was "try and break it." Leaderboard, tiered levels, a bit of prize money for anyone who got through. Never turned into a business. What it left behind was a year of logged, motivated, unpaid red-teaming against a detector that knew it was being attacked, which is a more interesting asset than the business ever was. Rather than let it sit in an RDS instance going stale, I've open-sourced the lot.

What it is: a two-stage filter that sits between user input and an LLM. Stage one is a regex gate, 119 patterns covering direct-override phrasing in about eleven languages, DAN/persona-style jailbreak framing, template-injection sigils ({{, ${), agentic chain-of-thought injection, homoglyph and zero-width-character stripping, with a decode-then-scan pass ahead of it that catches base64, ROT13 and leetspeak payloads before either the regex or the model sees them. Whatever the gate can't resolve falls through to a fine-tuned DeBERTa-v3-large, exported to ONNX and quantised to INT8. One thing I'll own upfront: the training script and config.json still describe a four-label head (benign/direct/jailbreak/indirect), but every training sample is actually labelled 0 or 1 and the exported graph only emits two logits. So the shipped model is a plain binary classifier. I caught this re-reading my own code a couple of weeks ago and corrected the docs rather than quietly leave the four-way claim standing.

Multimodal side pulls text out of images (OCR plus EXIF/PNG/XMP metadata fields, with a lossy re-encode first to kill LSB steganography and adversarial pixel perturbation), out of PDF/DOCX/XLSX/PPTX, and out of audio via ASR. Same two-stage pipeline runs over whatever comes out, tagged by modality so the model treats OCR and ASR text as noisier than typed text. Most open prompt-injection tooling I've come across only looks at the text field; I haven't seen another open-source detector that also scans images, documents and audio for injected payloads, so as far as I know this is the first one that does.

The bit worth your time here is the game logs. 13,230 attack strings, hand-written by real people trying to beat a live detector. No templates, no synthetic generation. Anonymised before publishing: identifiers and payment data dropped at the table level, emails/phone numbers/card-shaped digit runs redacted in the text itself, anything still risky after that pulled for manual review instead of auto-published. What ships is attack text plus a few coarse labels. Public injection datasets are almost all generated; this one is scraped from people actually trying.

Code: https://github.com/Josh-blythe/bordair-detector Dataset (synthetic + the real split): https://github.com/Josh-blythe/bordair-multimodal Weights: https://huggingface.co/Bordair/bordair-detector

Licensing: Apache-2.0 for the code and weights. Base model is microsoft/deberta-v3-large, MIT, attribution kept in NOTICE.

Threat model, so nobody's disappointed: this reads the prompt at inference time. Training-time and weight-level attacks are out of scope entirely. Treat it as a mitigation layer, one input among several a real deployment should have, not something you point at your LLM and forget about. I'd rather someone here find a trivial regex bypass now than have it sit unexamined, so have at it.

AI-Powered Analysis

Machine-generated threat intelligence

AILast updated: 07/22/2026, 18:22:07 UTC

Technical Analysis

The threat context involves a two-stage multimodal prompt injection detector that uses a fast regex gate followed by a quantized DeBERTa-v3-large ONNX binary classifier to identify malicious inputs aimed at bypassing LLM guardrails. The detector processes text, images (via OCR and metadata), documents (PDF, DOCX, XLSX, PPTX), and audio (via ASR) to detect injection payloads. The author ran a year-long incentivized red-teaming game where participants attempted to bypass the detector, resulting in a dataset of 13,230 anonymized real attack strings. The project is open-sourced with code, model weights, and dataset, licensed under Apache-2.0. The detector is positioned as a mitigation layer to be used alongside other defenses. No active exploit or vulnerability is described; rather, this is a research and defensive tool release.

Potential Impact

There is no direct impact from a vulnerability or exploit in this context. Instead, the impact is the availability of a dataset and detection tool that can help defenders identify and mitigate prompt injection and jailbreak attempts against LLMs. The dataset contains real-world adversarial inputs, which can improve detection capabilities and research. No known exploits or active attacks are reported. This resource may aid in strengthening defenses against prompt injection threats.

Defensive Guidance

This is not a vulnerability requiring patching but a defensive tool and dataset release. Users interested in mitigating prompt injection attacks can deploy the Bordair detector as a mitigation layer in front of LLMs. The detector combines regex filtering and a machine learning classifier to identify injection attempts across multiple input modalities. The author notes this should be one component of a layered defense strategy. No official patch or fix is applicable. Users should review the open-source code, model, and dataset to evaluate suitability for their environment.

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Technical Details

Source Type
reddit
Subreddit
netsec
Reddit Score
0
Discussion Level
minimal
Content Source
reddit_link_post
Post Type
link
Domain
null
Newsworthiness Assessment
{"score":27,"reasons":["external_link","established_author","very_recent"],"isNewsworthy":true,"foundNewsworthy":[],"foundNonNewsworthy":[]}
Has External Source
true
Trusted Domain
false

Threat ID: 6a610a459c2644c7f8793ab6

Added to database: 07/22/2026, 18:21:57 UTC

Last enriched: 07/22/2026, 18:22:07 UTC

Last updated: 09/04/2026, 18:10:51 UTC

Views: 108

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