Agent-Sentry: Bounding LLM Agents via Execution Provenance

Fuente: arXiv
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Autores principales: Sequeira, Rohan, Damianakis, Stavros, Iqbal, Umar, Psounis, Konstantinos
Formato: Preprint
Publicado: 2026
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author Sequeira, Rohan
Damianakis, Stavros
Iqbal, Umar
Psounis, Konstantinos
author_facet Sequeira, Rohan
Damianakis, Stavros
Iqbal, Umar
Psounis, Konstantinos
contents Agentic computing systems, while immensely capable, raise serious security, privacy, and safety concerns. A key issue is that the full set of functionalities offered by these systems, combined with their probabilistic execution flows, is not known beforehand. Given this lack of characterization, it is challenging to validate whether a system has successfully carried out the user's intended task or instead executed irrelevant actions, potentially as a consequence of compromise. We present \emph{Agent Sentry}, a runtime defense that learns a bound on an agent's benign execution from prior legitimate executions and flags any action that falls outside this bound. Agent Sentry layers three complementary checks: a structural classifier over the sequence of actions and the provenance of each function's arguments; a deterministic allowlist check over sensitive argument values; and an LLM judge, invoked only on the residual of actions where the first two checks cannot safely decide between a legitimate new request and a carefully crafted injection. We demonstrate the effectiveness of Agent Sentry in AgentDojo and AgentDyn by blocking 94.3\% of successful injections while allowing 95.1\% of benign executions, without modifying the agent, its tools, or the LLM.
format Preprint
id arxiv_https___arxiv_org_abs_2603_22868
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publishDate 2026
record_format arxiv
spellingShingle Agent-Sentry: Bounding LLM Agents via Execution Provenance
Sequeira, Rohan
Damianakis, Stavros
Iqbal, Umar
Psounis, Konstantinos
Cryptography and Security
Artificial Intelligence
Agentic computing systems, while immensely capable, raise serious security, privacy, and safety concerns. A key issue is that the full set of functionalities offered by these systems, combined with their probabilistic execution flows, is not known beforehand. Given this lack of characterization, it is challenging to validate whether a system has successfully carried out the user's intended task or instead executed irrelevant actions, potentially as a consequence of compromise. We present \emph{Agent Sentry}, a runtime defense that learns a bound on an agent's benign execution from prior legitimate executions and flags any action that falls outside this bound. Agent Sentry layers three complementary checks: a structural classifier over the sequence of actions and the provenance of each function's arguments; a deterministic allowlist check over sensitive argument values; and an LLM judge, invoked only on the residual of actions where the first two checks cannot safely decide between a legitimate new request and a carefully crafted injection. We demonstrate the effectiveness of Agent Sentry in AgentDojo and AgentDyn by blocking 94.3\% of successful injections while allowing 95.1\% of benign executions, without modifying the agent, its tools, or the LLM.
title Agent-Sentry: Bounding LLM Agents via Execution Provenance
topic Cryptography and Security
Artificial Intelligence
url https://arxiv.org/abs/2603.22868