Skip to content
Book Open access

Llama Models Security: From OWASPs Benchmarking to Encoding-based ​ obfuscation attacks​

Jul 2026 · Practice and Experience in Advanced Research Computing · 0 citations · 14 references
Computer Science

TL;DR

This work presents a two-phase evaluation of ten Llama variants using the OWASP Top 10 for LLM Applications, and applies nine encoding obfuscations to the same prompts, which fully bypasses all text-only models.

Abstract

As large language models (LLMs) are deployed in security-critical environments, evaluating their robustness against adversarial threats is essential. We present a two-phase evaluation of ten Llama variants using the OWASP Top 10 for LLM Applications. In Phase I we benchmark 100 OWASP-based adversarial prompts; Llama-Guard-3-1B leads (76% detection, 0.165 s latency, 0.94 GB VRAM), while base models detect nothing. In Phase II we apply nine encoding obfuscations to the same prompts (9,000 inferences): Base64 stays detectable (up to 100%), hexadecimal collapses to 2%, and ASCII art fully bypasses all text-only models. Model scale alone does not ensure robustness; targeted safety training and encoding-aware defenses are required. Both benchmark datasets are released for reproducibility [3].

Read PDF

Similar papers

Preprint Jul 2026

When Binaries Talk Back: Representation-Confusion Attacks on LLM-Assisted Reverse Engineering

LLM-assisted reverse-engineering (RE) systems analyze strings, decompiler output, and tool reports derived from ttacker-controlled binaries. A binary can make data look like instructions or records from one origin look like independent evidence. We call such failures Representation-Confusion Attacks in Reverse Engineering (RARE): the pipeline promotes a correctly extracted observation to instruction authority, claim-validating evidence, or trusted analysis state without the authority or support that role requires. RARE-Bench measures these failures with behavior-checked clean and adversarial binaries. After an exploratory 11,520-call study, we test RARE-Guard's authorization and evidence controls on 20 new programs and two models. Without runtime controls, the models propose a planted unsafe action in 35/40 adversarial cases and 0/40 clean cases. When binary-derived content is shown only as data (Data-Only rendering), they still make 15 unsafe proposals. Tool Authorization denies all 15 and authorizes all 40 matched analyst requests. On identical report drafts, Support Gate validates 23/40 false claims by counting records from one origin separately. Provenance Gate groups those records before counting support, validates 0/40 false claims, and retains all 40 supported claims. We then instrument Ghidra, r2pipe, and angr on 16 further programs. In a preselected eight-program subset, no single-tool draft reaches Support Gate's validation threshold for the false claim. In fused drafts across all 16 programs, Support Gate validates 32/32 false claims. Provenance Gate prevents validation of all 32 and retains all 32 supported claims. A deterministic renderer prevents downgraded claims from reappearing in the final report. Binary-derived content may therefore guide analysis without gaining authority over tools, and views from several tools do not necessarily provide independent evidence.

Igor Santos-Grueiro · 0 citations
Preprint Jul 2026

EXE-Bench: Ranking the Tradeoffs of AI-based Windows Malware Detectors for Real-World Usability

Due to the lack of systematic evaluations, we are not yet able to determine which AI-based Windows malware detector to deploy in production, since existing evaluations (i) differ in terms of data used for both training and testing; (ii) do not consider temporal analysis to showcase whether models withstand the passage of time; (iii) avoid security evaluations with adversarial attacks that could highlight their brittleness against content-injection attacks; and (iv) neglect the computational requirements for deployment, risking slow inference on endpoints. For these reasons, we develop EXE-Bench, a comprehensive benchmark of AI-based Windows malware detectors. EXE-Bench assesses performance, temporal and adversarial robustness, and computational overhead, aggregating them into a single score for direct and fair model comparison. Through EXE-Bench, we highlight how evaluations conducted only after deployment are suboptimal and unable to provide a complete picture of their performance. In particular, through our analysis, we remark how much domain knowledge instilled through feature engineering is still extremely useful in this domain, resisting both time and adversarial attacks, in stark contrast with most of the deep networks that only excel right after deployment.

Andrea Ponte, Daniel Gibert, M. Kozák et al. · 0 citations
Preprint Jul 2026

Just Testing, Move Along: Evasion of LLM-based System Log Interpretation by Prompt Injection

This paper presents a framework for evaluating prompt injection attacks against LLM-based log interpretation using log traces generated during real cyber attacks, and creates adversarial examples through generic injection generation, refinement, and attack-specific optimization.

Max Landauer, Florian Skopik, Markus Wurzenberger et al. · 0 citations
Conference Jul 2026

Generating Attacks for LLM with GFlowNets

The rapid advancement of Large Language Models (LLMs) has facilitated their ubiquitous integration into various domains, leading to widespread adoption. However, this escalating trend has introduced significant security vulnerabilities, necessitating the identification and mitigation of flaws arising from malicious exploitation. Red teaming assessments, conducted to evaluate model robustness through diverse adversarial inputs, are essential for exposing security risks and implementing countermeasures. Currently, red teaming is performed either manually by experts or automatically using predefined attack datasets. Nevertheless, manual testing remains time-consuming, while existing automated methods suffer from limited creativity due to their inherent dependency on fixed datasets. In this study, we propose an automated, human-independent, and adaptive approach leveraging GFlowNets to identify LLM vulnerabilities by utilizing one large language model to test another. Within this framework, an attacker model is trained against a specified victim model to perform automated red teaming and provide a quantitative robustness score. This research aims to generate more effective adversarial attacks in English compared to existing benchmarks and, as a novel contribution to the literature, introduces a model capable of generating attack inputs in the Turkish language.

Berkay Özçam, İrem Önen, E. I. Tatli et al. · 0 citations
Preprint Aug 2026

Generating Attacks for LLMs with GFlowNets

This study proposes an automated, human-independent, and adaptive approach leveraging GFlowNets to identify LLM vulnerabilities by utilizing one large language model to test another, and introduces a model capable of generating attack inputs in the Turkish language.

Berkay Ozcam, Irem Onen, M. Amasyalı et al. · 0 citations
Book Open access Jul 2026

SecMutBench: Evaluating LLM-Generated Security Tests via Mutation-Based Vulnerability Detection

Existing LLM security benchmarks evaluate code generation quality, leaving an open question: can LLMs generate tests that detect vulnerabilities? We address this with two technical contributions. First, we propose the Security Mutation Score (SMS), a metric that classifies mutant kills into semantic, functional, incidental, and crash categories using operator-aware heuristics, distinguishing genuine security awareness from coincidental detection. We further define Effective SMS (EffSMS = SMS × Secure-Pass Rate) to account for test validity. Second, we design 25 security-specific mutation operators spanning 30 CWE categories that transform secure Python code into realistic vulnerable variants, extending prior security mutation frameworks to Python and introducing 22 new operators. Evaluating eight LLMs and two static analysis baselines on 339 programs and 1,869 mutants reveals three findings: (i) traditional mutation scores overstate LLM security testing capability by 2.2× on average; (ii) the best LLM achieves only 19.7% EffSMS vs. 47.6% for expert-written tests—a 2.4× gap raw metrics obscure; and (iii) functional kills, not crashes, dominate non-semantic failures (15–36%), showing LLMs detect behavioral side-effects rather than security properties. Static analysis and mutation testing provide complementary coverage across syntactic vs. logic-flaw CWEs. Code and data are publicly available.

Mariam Almutairi, Chang-Tien Lu · 0 citations