Red teaming is essential for securing Large Language Models, yet current automated methods remain limited by templates and single-turn attacks. To simulate the complex, interactive nature of real-world adversarial attacks, we introduce a novel red teaming paradigm designed to maximize expected cumulative harm through strategic interaction. By formalizing red teaming as a Markov Decision Process in a hierarchical reinforcement learning framework, we navigate the challenges of sparse rewards and long-horizon planning. Our generative agent learns diverse, multi-turn attacks using a token-level harm reward, consistently uncovering vulnerabilities that bypass baselines. This approach achieves a new state of the art and reframes LLM red teaming as a principled, trajectory-based process.
Figures & tables
Figure 1: An adversarial conversation between the red team agent and the target LLM. The dialogue state consists of alternating Target and Low-Level Policy utterances.
Figure 2: Overview of red teaming as an HRL problem. The high-level policy π1 learns a strategy over a dialogue trajectory and provides guides to the low-level policy. The low-level policy π2 generates the action to send to the target model based on the state and guide.
Method
Llama-3.1-8B-Instruct
GPT-5.4-mini
Myopic
Context-Aware
Myopic
Context-Aware
↑ ASR
↓ TtS
↑ ASR
↓ TtS
↑ ASR
↓ TtS
↑ ASR
↓ TtS
LLM-HL (Ours)
75.2
3.66
62.5
3.8
35.0
2.52
41.0
4.68
Ferret [ 9 ]
31.25
3.87
23.8
4.45
5.0
4.75
0.0
-
WildTeaming [ 22 ]
65.0
3.53
10.3
4.36
4.5
4.66
0.0
-
HARM [ 55 ]
10.2
4.97
17.5
4.97
24.7
4.9
20.0
4.95
Table 1: Our method outperforms baselines on Harmbench data, attacking open source and closed source reasoning models, under few-shot (ASR@5) settings described in Section 5 . We report the average turns to success (TtS); methods with zero success have TtS of nil (-).
Method
Llama-3.1-8b-Instruct
Llama-3.1-70b-Instruct
GPT-4o
——–Average——–
↑ HB
↑ WB
↑ JB
↑ HB
↑ WB
↑ JB
↑ HB
↓ PPL
↓ TtS
↑ Div
LLM-HL (Ours)
95.0
76.0
77.5
86.5
78.0
66.0
55.0
13.3
4.1
0.92
Template-HL (Ours)
96.0
74.5
75.0
89.1
72.0
63.0
43.5
7.2
4.4
0.85
Low-level Only (Ours)
35.0
27.0
19.5
24.5
18.5
13.0
12.5
19.3
5.8
0.55
Ferret [ 9 ]
82.5
63.0
68.5
81.7
39.5
58.0
18.7
12.3
7.5
0.58
Wildteaming [ 22 ]
76.1
77.5
40.0
45.7
45.0
22.0
15.0
8.1
6.2
0.65
Table 2: Experiments in a 30-step, context-aware setting (ASR@30) against open and closed-source models of varying size, using WildBench (WB), JailbreakBench (JB), and the validation set of Harmbench (HB). We also report mean perplexity (PPL), turns to success (TtS), and pairwise cosine distance for attack embeddings, i.e., Diversity (Div).
Table 3: Sensitivity testing to model architectures. In 3 3(a) , we ablate guard models used in training as the immediate reward. The ability of the red teamer is roughly correlated with the strength of the guard model. In 3 3(b) , we show the effect of freezing each level during training. While each frozen method outperforms baselines, indicating the advantages of hierarchy, the comprehensive method is required for SOTA results. We use Harmbench data and attack Llama-3.1-8b-Instruct in these tables.
Figure 6
Appendix figures & tables3 assets
Supplementary material from the paper’s appendix.
Appendix
Method
Llama-3.1-8b-Instruct
Llama-3.1-70b-Instruct
Mixtral-8x22b
GPT-4o
↑ HB
↑ WB
↑ JB
↑ HB
↑ WB
↑ JB
↑ HB
↑ WB
↑ JB
↑ HB
Template-HL (Ours)
97.0
74.5
75.0
89.1
72.0
63.0
90.0
79.5
66.5
43.5
Low-level Only (Ours)
35.0
27.0
19.5
24.5
18.5
13.0
38.0
29.0
21.5
12.5
LLM-HL (Ours)
97.0
76.0
77.5
87.0
78.0
66.0
90.0
82.5
69.5
55.0
Ferret [ 9 ]
82.5
63.0
68.5
81.7
39.5
58.0
50.5
37.0
46.0
18.7
Wildteaming [ 22 ]
76.1
77.5
40.0
45.7
45.0
22.0
55.0
61.5
27.5
15.0
Appendix
Table 4: Experimental results measuring ASR in a 30-step, context-aware setting (ASR@30) against open and closed source models covering a range of model sizes. Seed prompts are procured from WildBench (WB) [ 28 ] , JailbreakBench (JB) [ 5 ] , and the validation set of Harmbench (HB) [ 32 ] .
Figure 4: We track the transition matrix denoting the frequency that one action follows another to illustrate the existence of a distribution over strategies.
Figure 5: Comparison of critic and policy model losses under different reward attribution methods.
Automated methods for red teaming LLMs are an important tool to identify LLM vulnerabilities that may not be covered in static benchmarks, allowing for more thorough probing. They can also adapt to each specific LLM to discover weaknesses unique to it. Most current automated red teaming methods are intended for tackling safety and content moderation. Thus, they make use of content safety models as evaluators and optimize for circumventing them, and as such, have not been tested with other adversarial intents not typically captured by these. We propose a pipeline for training a red teaming model that can generalize to arbitrary adversarial goals, including objectives it has not been directly trained on, and that does not depend on the existence of a pre-existing evaluator available at training time. We demonstrate that finetuning small models, such as Qwen3-8B, using this pipeline results in a substantial improvement in their ability to generate attacks for both in and out of domain adversarial goals.
Aishwarya Padmakumar, Leon Derczynski, Traian Rebedea +1
Automated red-team attacks and blue-team defenses for large language models (LLMs) are advancing quickly. However, attackers and defenders are built and tested in isolation, and the resulting scores are hard to trust. To tackle this, we present ACEA (Adversarial Co-Evolution Arena), a platform that connects a pluggable red-team adapter and a pluggable blue-team adapter to a shared target LLM and scores their attack and defense rates with an LLM judge. ACEA contributes four components. First, a pluggable, model-agnostic arena. Any red or blue project connects over a minimal HTTP protocol, which we call the ACEA Standard Adapter Protocol (ASAP). It can be written in any language, and a project that exposes nothing but the protocol is a full participant. Second, an evaluation methodology built for adversarial rounds. Seeding the target with canonical secrets gives verifiable ground truth that separates real leakage from hallucination. We also send each attack to the target even when the defense blocks it, which measures the attack's raw potency independently of whether it was stopped. Together these yield a per-round decomposition of attack strength and defense effectiveness. Third, a real-time, game-style visualization with a detailed end-of-battle report that localizes each failure. The evaluation thus becomes an actionable signal for improving a red or blue project. Fourth, an optional in-context improvement loop that turns each round's outcome into advisory hints for the next. An adapter can then adapt across rounds without keeping state, provided it reads the hints. We describe the design of ACEA and the metrics through which red and blue teams are scored head to head.
While Large Language Models (LLMs) are widely used, they remain susceptible to jailbreak prompts that can elicit harmful or inappropriate responses. This paper introduces STAR-Teaming, a novel black-box framework for automated red teaming that effectively generates such prompts. STAR-Teaming integrates a Multi-Agent System (MAS) with a Strategy-Response Multiplex Network and employs network-driven optimization to sample effective attack strategies. This network-based approach recasts the intractable high-dimensional embedding space into a tractable structure, yielding two key advantages: it enhances the interpretability of the LLM's strategic vulnerabilities, and it streamlines the search for effective strategies by organizing the search space into semantic communities, thereby preventing redundant exploration. Empirical results demonstrate that STAR-Teaming significantly surpasses existing methods, achieving a higher attack success rate (ASR) at a lower computational cost. Extensive experiments validate the effectiveness and explainability of the Multiplex Network. The code is available at https://github.com/selectstar-ai/STAR-Teaming-paper.