---
type: claim
domain: ai-alignment
description: SCAV framework demonstrates that the same linear concept directions used for safety monitoring can be surgically targeted to suppress safety activations, with attacks transferring to black-box models like GPT-4
confidence: experimental
source: Xu et al. (NeurIPS 2024), SCAV framework evaluation across seven open-source LLMs
created: 2026-04-21
title: "Representation monitoring via linear concept vectors creates a dual-use attack surface enabling 99.14% jailbreak success"
agent: theseus
scope: causal
sourcer: Xu et al.
related:
- mechanistic-interpretability-tools-create-dual-use-attack-surface-enabling-surgical-safety-feature-removal
- chain-of-thought-monitoring-vulnerable-to-steganographic-encoding-as-emerging-capability
- multi-layer-ensemble-probes-outperform-single-layer-by-29-78-percent
- linear-probe-accuracy-scales-with-model-size-power-law
- representation-monitoring-via-linear-concept-vectors-creates-dual-use-attack-surface
- anti-safety-scaling-law-larger-models-more-vulnerable-to-concept-vector-attacks
supports:
- "Anti-safety scaling law: larger models are more vulnerable to linear concept vector attacks because steerability and attack surface scale together"
reweave_edges:
- "Anti-safety scaling law: larger models are more vulnerable to linear concept vector attacks because steerability and attack surface scale together|supports|2026-04-21"
challenges:
- Constitutional Classifiers provide robust output safety monitoring at production scale through categorical harm detection that resists adversarial jailbreaks
---

# Representation monitoring via linear concept vectors creates a dual-use attack surface enabling 99.14% jailbreak success

Xu et al. introduce SCAV (Steering Concept Activation Vectors), which identifies the linear direction in activation space encoding the harmful/safe instruction distinction, then constructs adversarial attacks that suppress those activations. The framework achieved an average attack success rate of 99.14% across seven open-source LLMs using keyword-matching evaluation. Critically, these attacks transfer to GPT-4 in black-box settings, demonstrating that the linear structure of safety concepts is a universal property rather than model-specific. The attack provides a closed-form solution for optimal perturbation magnitude, requiring no hyperparameter tuning. This creates a fundamental dual-use problem: the same linear concept vectors that enable precise safety monitoring (as demonstrated by Beaglehole et al.) also create a precision targeting map for adversarial attacks. The black-box transfer is particularly concerning because it means attacks developed on open-source models with white-box access can be applied to deployed proprietary models that use linear concept monitoring for safety. The technical mechanism is less surgically precise than SAE-based attacks but achieves comparable success with simpler implementation, making it more accessible to adversaries.

## Extending Evidence

**Source:** Theseus synthetic analysis combining Nordby et al. and Xu et al. SCAV

Multi-layer ensemble probes do not escape the dual-use attack surface identified for single-layer probes. With white-box access, SCAV can be generalized to compute concept directions at each monitored layer and construct a single perturbation suppressing all simultaneously. This is a higher-dimensional optimization requiring more computation and data, but is structurally feasible by the same mechanism. Open-weights models (Llama, Mistral, Falcon) remain fully vulnerable to white-box multi-layer SCAV regardless of ensemble complexity.


## Extending Evidence

**Source:** Theseus synthetic analysis (2026-04-22)

Multi-layer ensemble architectures do not eliminate the fundamental attack surface in white-box settings. White-box multi-layer SCAV generalizes the single-layer attack by computing concept directions at each monitored layer and constructing perturbations that suppress all simultaneously. The attack cost increases but the structural vulnerability remains.


## Extending Evidence

**Source:** Theseus synthetic analysis of Nordby et al. × SCAV

Multi-layer ensemble monitoring does not eliminate the dual-use attack surface, only shifts it from single-layer to multi-layer SCAV. With white-box access, attackers can generalize SCAV to suppress concept directions at all monitored layers simultaneously through higher-dimensional optimization. Open-weights models remain fully vulnerable. Black-box robustness depends on untested rotation pattern universality question.