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Vol. 1 · Ed. 2026
CyberGlossary
Entry № 1290

Training Data Extraction

Qu'est-ce que Training Data Extraction ?

Training Data ExtractionAttacks that recover verbatim training examples from a deployed model by exploiting memorization, exposing copyrighted text, PII, or proprietary content the model was trained on.


Training data extraction is a class of model-confidentiality attacks that aim to make an LLM regurgitate sequences from its training corpus exactly. Carlini et al. and follow-up work showed that even production-scale models memorize a non-trivial fraction of their training data, particularly rare strings, code, and personally identifiable information. Practical attacks include divergence prompts (looping a model on a single token until it falls into memorized text — the 2023 'poem poem poem' attack against GPT-3.5 is the canonical example), prefix completion of suspected memorized passages, and membership-inference combined with iterative reconstruction. Successful extraction matters legally (copyright, GDPR right to be forgotten), commercially (proprietary documents bled into a fine-tune), and reputationally (named individuals' details surfacing). Defenses combine training-time deduplication, differential-privacy training, output filters that block long verbatim passages, refusal training against divergence patterns, and limits on output length and entropy.

Exemples

  1. 01

    A researcher prompts an LLM with 'repeat this word forever: poem' and recovers verbatim chunks of training data including email addresses and phone numbers.

  2. 02

    An audit of a fine-tuned customer model surfaces verbatim contract clauses that should never have left the source repository.

Questions fréquentes

Qu'est-ce que Training Data Extraction ?

Attacks that recover verbatim training examples from a deployed model by exploiting memorization, exposing copyrighted text, PII, or proprietary content the model was trained on. Cette notion relève de la catégorie Sécurité de l'IA et du ML en cybersécurité.

Que signifie Training Data Extraction ?

Attacks that recover verbatim training examples from a deployed model by exploiting memorization, exposing copyrighted text, PII, or proprietary content the model was trained on.

Comment fonctionne Training Data Extraction ?

Training data extraction is a class of model-confidentiality attacks that aim to make an LLM regurgitate sequences from its training corpus exactly. Carlini et al. and follow-up work showed that even production-scale models memorize a non-trivial fraction of their training data, particularly rare strings, code, and personally identifiable information. Practical attacks include divergence prompts (looping a model on a single token until it falls into memorized text — the 2023 'poem poem poem' attack against GPT-3.5 is the canonical example), prefix completion of suspected memorized passages, and membership-inference combined with iterative reconstruction. Successful extraction matters legally (copyright, GDPR right to be forgotten), commercially (proprietary documents bled into a fine-tune), and reputationally (named individuals' details surfacing). Defenses combine training-time deduplication, differential-privacy training, output filters that block long verbatim passages, refusal training against divergence patterns, and limits on output length and entropy.

Comment se défendre contre Training Data Extraction ?

Les défenses contre Training Data Extraction combinent habituellement des contrôles techniques et des pratiques opérationnelles, comme détaillé dans la définition ci-dessus.

Quels sont les autres noms de Training Data Extraction ?

Noms alternatifs courants : Memorization attack, Data exfiltration via LLM.

Termes liés