PIIGuard: Mitigating PII Harvesting under Adversarial Sanitization
Browsing-enabled LLM assistants can fetch webpages and answer contact-seeking queries, creating a practical channel for scraping contact-style personally identifiable information (PII) from public pages. Many prior defenses are deployed at the model, service, or agent layer rather than at the webpage itself, leaving ordinary page owners with limited deployable options. We present PIIGuard, a webpage-level defense that repurposes indirect prompt injection as a protective mechanism: the page owner embeds optimized hidden HTML fragments that steer the model away from verbatim or reconstructible disclosure of contact PII. PIIGuard searches over fragment text and insertion position using rule-...
| Authors | Mingshuo Liu, Yiwei Zha, Min Chen |
|---|---|
| Primary category | cs.CR |
| Published | 4 May 2026 |
| Last updated at source | 4 May 2026 |
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