"Ghost of the past": identifying and resolving privacy leakage from LLM's memory through proactive user interaction

AuthorsShuning Zhang, Lyumanshan Ye, Xin Yi et al.

2024

TL;DR

MemoAnalyzer uses prompt-based privacy inference plus visual memory editing to cut inferred private items by up to 22.3% versus GPT-style memory without slowing users down.

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THE PROBLEM

Users are unaware of LLM memory privacy risks (30 of 40 miss long term memory)

Most participants had no idea long term RAG based memory existed, with only 5 of 40 understanding long term mechanisms.

Even frequent users misbelieved memory was per dialogue or shareable, leaving sensitive information silently stored and reused without privacy awareness.

HOW IT WORKS

MemoAnalyzer — prompt based privacy inference and visual memory control

MemoAnalyzer combines Privacy Inference, Sensitivity Highlighting, Source Tracking, and an Editing Proxy to expose and manage private information in memories.

You can think of MemoAnalyzer like a debugger overlay on top of LLM memory, showing which past lines of "code" generated each privacy relevant inference.

This KEY_MECHANISM lets MemoAnalyzer proactively surface and edit sensitive traces that a plain context window or opaque memory panel would silently reuse or train on.

DIAGRAM

User–MemoAnalyzer interaction around each LLM turn

This diagram shows how MemoAnalyzer wraps each LLM interaction with notification, inspection, and editing of inferred private information.

DIAGRAM

Five day evaluation pipeline for MemoAnalyzer

This diagram shows the 5 day within subject study design comparing MemoAnalyzer, GPT memory, and Manual baselines on three task types.

PROCESS

How MemoAnalyzer Handles a Memory Aware Chat Session

  1. 01

    Memory generation

    MemoAnalyzer lets the GPT-4o backend extract long term memories while tagging each entry so Source Tracking and the Editing Proxy can later locate it.

  2. 02

    Privacy inference

    MemoAnalyzer aggregates past inputs and memories, then runs prompt based Privacy Inference to list sensitive items with confidence and type annotations.

  3. 03

    Sensitivity highlighting and source tracking

    MemoAnalyzer uses Sensitivity Highlighting to color code items and Source Tracking to expand the exact past inputs and memories with yellow keywords.

  4. 04

    Editing proxy and update

    Through the Editing Proxy, MemoAnalyzer applies user edits or deletions back to stored histories, ensuring future training or inference uses sanitized memories.

KEY CONTRIBUTIONS

Key Contributions

  • 01

    Unveiling opaque LLM memory mechanisms

    MemoAnalyzer builds on a semi structured interview (N=40) showing 30 of 40 users were unaware of long term RAG based memory and its privacy risks.

  • 02

    Design and implementation of MemoAnalyzer

    MemoAnalyzer integrates Privacy Inference, Sensitivity Highlighting, Source Tracking, and an Editing Proxy into a pop up interface that visualizes and manages private information.

  • 03

    Five day evaluation of MemoAnalyzer

    In a 5 day in lab study (N=36), MemoAnalyzer reduced inferred private items by 22.3% versus GPT memory while maintaining comparable completion time and improving perceived control.

RESULTS

By the Numbers

Total inferred private items (GPT-4o)

−22.3% vs GPT

22.3% fewer inferred private items than GPT memory

Total inferred private items (Qwen 72B)

−22.3% vs GPT

similar reduction pattern compared to GPT and Manual baselines

Participants unaware of long term memory

30 of 40

shows initial opacity MemoAnalyzer must address

Study 2 sample size

36 participants

within subject comparison across MemoAnalyzer, GPT, and Manual

These numbers come from the 5 day user study and offline privacy inference tests using GPT-4o and Qwen models. They show MemoAnalyzer can materially reduce exploitable private information in LLM memories without adding interaction time.

BENCHMARK

By the Numbers

These numbers come from the 5 day user study and offline privacy inference tests using GPT-4o and Qwen models. They show MemoAnalyzer can materially reduce exploitable private information in LLM memories without adding interaction time.

BENCHMARK

Reduction in inferred private information after 5 days

Relative number of inferred private items per participant when GPT-4o analyzes histories from each technique.

KEY INSIGHT

The Counterintuitive Finding

Despite adding a new privacy interface, MemoAnalyzer kept total task time comparable to GPT and Manual, with 460.3s vs 426.2s and 462.7s respectively.

You might expect proactive privacy checks to slow users dramatically, but MemoAnalyzer’s visualization and Editing Proxy avoided extra overhead while still reducing private leakage.

WHY IT MATTERS

What this unlocks for the field

MemoAnalyzer shows that LLM memory can be made transparent and user editable, even when built on opaque GPT style memory APIs.

Builders can now design RAG and long term memory systems where users see, understand, and reshape inferred private facts before they ever reach training pipelines.

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Paper: "Ghost of the past": identifying and resolving privacy leakage from LLM's memory through proactive user interaction

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