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Keywords = indirect prompt injection

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31 pages, 1570 KB  
Article
Design of a Security Framework for Multi-Agent Systems Based on Model Context Protocol in SOC Environments
by Rodrigo Tavares de Pina Simões, Xavier Larriva-Novo, Carmen Sánchez-Zas, Victor A. Villagrá and Andrés I. Marín López
Appl. Sci. 2026, 16(16), 7915; https://doi.org/10.3390/app16167915 - 8 Aug 2026
Viewed by 383
Abstract
Security Operations Centers (SOCs) rely on Level 1 analysts to triage increasing alert volumes amid alert fatigue and tool fragmentation. LLM-based multi-agent systems using the Model Context Protocol (MCP) are being adopted to automate these tasks, but their autonomy and tool access expose [...] Read more.
Security Operations Centers (SOCs) rely on Level 1 analysts to triage increasing alert volumes amid alert fatigue and tool fragmentation. LLM-based multi-agent systems using the Model Context Protocol (MCP) are being adopted to automate these tasks, but their autonomy and tool access expose them to attacks such as tool poisoning, indirect prompt injection, and confused deputy exploitation. To address this gap, this work proposes a security framework for MCP-based multi-agent SOC pipelines, implemented as a middleware layer comprising a tool registration validator and five execution layers: access control, rate limiting, input validation, output validation, and audit logging. The framework is applied to a triage-enrichment-response pipeline connected to a Wazuh SIEM through a custom MCP server. Of the 35 attack vectors considered in a threat model derived from different threat taxonomies, including OWASP, MITRE ATLAS, and ATFAA, 29 are addressable at the middleware level and are covered by the framework’s controls. These controls are then validated experimentally using a purpose-built malicious MCP server and targeted test-harness injections, organized into six test suites that together exercise the covered vectors across 600 executions. Every attack instance in the evaluated threat model was blocked, none bypassed the framework, and no legitimate call in the evaluated set was incorrectly rejected; obfuscated variants, however, evade the lexical content-inspection controls, delimiting the scope of this result. A full-pipeline demonstration confirms that the framework preserves benign operational outputs. These results indicate that systematic middleware controls can secure MCP-based agentic SOC deployments without modifying the underlying agents or MCP servers. Full article
(This article belongs to the Special Issue Recent Trends in Cybersecurity, Privacy, and Digital Trust)
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34 pages, 969 KB  
Article
Balancing Security and Performance in LLM Agents: Spotlight-Guard, a Layered Defense Against Indirect Prompt Injection
by Doygun Demirol and Murat Aydogan
Appl. Sci. 2026, 16(15), 7662; https://doi.org/10.3390/app16157662 - 2 Aug 2026
Viewed by 442
Abstract
Large Language Model (LLM)-based agents automate complex tasks by integrating external tools such as web browsers, e-mail clients, file readers, and APIs, but this same integration exposes them to indirect prompt injection (IPI) attacks, in which malicious instructions hidden in tool content hijack [...] Read more.
Large Language Model (LLM)-based agents automate complex tasks by integrating external tools such as web browsers, e-mail clients, file readers, and APIs, but this same integration exposes them to indirect prompt injection (IPI) attacks, in which malicious instructions hidden in tool content hijack the agent. A central but often overlooked question is how defending against such attacks affects the LLM and its own task performance and computational efficiency. In this study, we design a comprehensive testbed and a layered defense, Spotlight-Guard, that combines spotlighting-based input isolation, an LLM detection-and-quarantine pipeline, and instruction integrity based on a Hash-based Message Authentication Code (HMAC) into a single framework, and we evaluate it jointly along two axes: security and LLM performance. Experiments on locally hosted 7B-class open-weight models (Qwen-2.5-7B, Mistral-7B, and DeepSeek-Coder) use Attack Success Rate (ASR) for security and benign-task success rate together with confusion-matrix-based metrics (precision, recall, and F1) for task performance, all with bootstrap 95% confidence intervals. Across a stratified, fixed-seed benchmark of 250 adversarial and 250 benign cases per configuration, the full system reduces the ASR from 36.0% to 17.2% while preserving a 97.2% benign-task success rate and raising the detection F1 from 0.749 to 0.892, demonstrating that strong protection need not degrade the model’s task performance. A component ablation isolates each layer’s contribution, an adaptive-attack evaluation confirms a low ASR (6.7%) under attacks crafted to target the pipeline, and an analysis of computational cost (model invocations per request) quantifies the efficiency overhead, characterizing the security–performance trade-off of layered defenses on open-weight LLMs. Full article
(This article belongs to the Section Computing and Artificial Intelligence)
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31 pages, 2888 KB  
Article
Runtime Policy Enforcement for MCP-Based LLM Agents
by Shanshan Wang, Sizheng Zhu and Rende Li
Electronics 2026, 15(13), 2829; https://doi.org/10.3390/electronics15132829 - 27 Jun 2026
Cited by 2 | Viewed by 941
Abstract
Tool-calling LLM agents are vulnerable to indirect prompt injection: externally retrieved data can redirect tool calls without system-prompt access, and prompt-level defences leave three harm classes undefended (path traversal, user-guided exfiltration, high-frequency tool abuse). We present a Policy Enforcement Point (PEP) that intercepts [...] Read more.
Tool-calling LLM agents are vulnerable to indirect prompt injection: externally retrieved data can redirect tool calls without system-prompt access, and prompt-level defences leave three harm classes undefended (path traversal, user-guided exfiltration, high-frequency tool abuse). We present a Policy Enforcement Point (PEP) that intercepts at the tool-call boundary with declarative rules over a cross-step information-flow label system (source integrity, data sensitivity) and a synchronous SHA-256 hash-chained audit log. On a controlled dataset across four attack classes, the full system cuts the attack success rate (ASR) from 40.0% to 5.0% (deepseek-v4-pro, five repeats) versus 35.0% for the strongest prompt-only baseline; disabling cross-step label propagation raises the call-level false-negative rate by 26.4 points. The 30.0% task-level false-positive rate is dominated by by-design least-privilege capability-token denials, not rule false positives—an expanded 30-task benign set yields 0/30 rule false positives under scripted isolation. A conservative-DS mitigation (intent-taint) closes the constructed denied-read reconstruction blind-spot variant (ASR 100% to 0%) at no cost on standard workflows. The audit log detects all three tested tamper classes; the in-process enforcement overhead is sub-millisecond per call. Across four further backends, ASR drops under the full system, though LLaMA-3.3-70B retains 16.7% (a rule-coverage gap). A preliminary run over a real MCP stdio transport (an official filesystem server) shows the mechanism operates at a real boundary with a sub-millisecond execution-path increment. We frame these as mechanism-coverage evidence on a controlled benchmark, not a deployability claim for production MCP workloads. Code, data, and metrics are openly available in the replication repository. Full article
(This article belongs to the Special Issue AI for Cybersecurity and Emerging Technologies for Secure Systems)
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36 pages, 1271 KB  
Article
Securing Tool-Using AI Agents Against Injection and Authority Misuse
by Hasan Kanaker, Hussam Fakhouri, Nader Abdel Karim, Maher Abuhamdeh, Nurul Halimatul Asmak Ismail and Sandi Fakhouri
Computation 2026, 14(5), 98; https://doi.org/10.3390/computation14050098 - 25 Apr 2026
Viewed by 1484
Abstract
Tool-using AI agents couple a language model with controller logic, memory, and external tools such as browsers, email, calendars, file systems, and transaction APIs. This architecture expands capability, but it also enlarges the security boundary: agents routinely ingest untrusted content while holding privileges [...] Read more.
Tool-using AI agents couple a language model with controller logic, memory, and external tools such as browsers, email, calendars, file systems, and transaction APIs. This architecture expands capability, but it also enlarges the security boundary: agents routinely ingest untrusted content while holding privileges that can reveal private data and trigger external side effects. The resulting failures are not limited to poor text generation; they include prompt injection, indirect injection through tool outputs, confused-deputy behavior, unauthorized actions, and misleading claims about the tool state. Because large-scale testing on deployed products is difficult, vendor-specific, and ethically sensitive, we present a transparent, theoretical simulation-based framework for evaluating user-facing risk in tool-using agents. The methodological contribution is a formal threat model that separates compromise, harm, and severity, and a Monte Carlo evaluation pipeline that maps architectural choices (permissions, retrieval, memory exposure, and approvals) and defensive controls to comparable outcome metrics. We instantiate the framework for six representative threat scenarios and nine defense configurations, reporting attack success rate (ASR), benign task success, latency overhead, and severity-weighted harm. Across scenarios, the least-privilege tool design is the strongest single broad control, human-in-the-loop approvals sharply reduce high-impact actions and exports but degrade under user error and habituation, retrieval allowlisting nearly eliminates indirect injection while leaving other channels largely unaffected, and rate limiting reduces tail severity more than ASR. These results position agent safety as an architectural and operational problem and because they arise from an assumption-explicit simulator rather than field measurements, should be read as comparative design guidance rather than incident-rate estimates for any deployed product. Full article
(This article belongs to the Section Computational Engineering)
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51 pages, 1932 KB  
Review
Federated Retrieval-Augmented Generation for Cybersecurity in Resource-Constrained IoT and Edge Environments: A Deployment-Oriented Scoping Review
by Hangyu He, Xin Yuan, Kai Wu and Wei Ni
Electronics 2026, 15(7), 1409; https://doi.org/10.3390/electronics15071409 - 27 Mar 2026
Cited by 2 | Viewed by 1598
Abstract
Cybersecurity operations in IoT and edge environments require fast, evidence-grounded decisions under strict resource and trust constraints. While large language models can support triage and incident analysis, their parametric knowledge may be outdated and prone to hallucination. Retrieval-augmented generation (RAG) improves grounding by [...] Read more.
Cybersecurity operations in IoT and edge environments require fast, evidence-grounded decisions under strict resource and trust constraints. While large language models can support triage and incident analysis, their parametric knowledge may be outdated and prone to hallucination. Retrieval-augmented generation (RAG) improves grounding by conditioning responses on retrieved evidence, but also introduces new risks such as knowledge-base poisoning, indirect prompt injection, and embedding leakage. Federated learning enables collaborative adaptation without centralizing sensitive data, motivating federated RAG (FedRAG) architectures for distributed cybersecurity deployments. This study presents a deployment-oriented scoping review of FedRAG for cybersecurity. The review follows PRISMA-ScR reporting guidance and synthesizes 82 studies published between 2020 and 2026, identified through keyword search and citation snowballing over OpenAlex, arXiv, and Crossref. We develop a taxonomy that clarifies the components of federated systems, deployment locations, trust boundaries, and protected assets. We further map the combined RAG+FL attack surface, summarize practical defenses and system patterns, and distill actionable guidance for secure, privacy-preserving, and efficient FedRAG deployment in real-world IoT and edge scenarios. Our synthesis highlights recurring trade-offs among robustness, privacy, latency, communication overhead, and maintainability, and identifies open research priorities in benchmark design, governance mechanisms, and cross-silo evaluation protocols for practical deployment. Full article
(This article belongs to the Special Issue Novel Approaches for Deep Learning in Cybersecurity)
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21 pages, 1401 KB  
Article
Embedding-Based Detection of Indirect Prompt Injection Attacks in Large Language Models Using Semantic Context Analysis
by Mohammed Alamsabi, Michael Tchuindjang and Sarfraz Brohi
Algorithms 2026, 19(1), 92; https://doi.org/10.3390/a19010092 - 22 Jan 2026
Cited by 2 | Viewed by 4083
Abstract
Large Language Models (LLMs) are vulnerable to Indirect Prompt Injection Attacks (IPIAs), where malicious instructions are embedded within external content rather than direct user input. This study presents an embedding-based detection approach that analyses the semantic relationship between user intent and external content, [...] Read more.
Large Language Models (LLMs) are vulnerable to Indirect Prompt Injection Attacks (IPIAs), where malicious instructions are embedded within external content rather than direct user input. This study presents an embedding-based detection approach that analyses the semantic relationship between user intent and external content, enabling the early identification of IPIAs that conventional defences overlook. We also provide a dataset of 70,000 samples, constructed using 35,000 malicious instances from the Benchmark for Indirect Prompt Injection Attacks (BIPIA) and 35,000 benign instances generated using ChatGPT-4o-mini. Furthermore, we performed a comparative analysis of three embedding models, namely OpenAI text-embedding-3-small, GTE-large, and MiniLM-L6-v2, evaluated in combination with XGBoost, LightGBM, and Random Forest classifiers. The best-performing configuration using OpenAI embeddings with XGBoost achieved an accuracy of 97.7% and an F1-score of 0.977, matching or exceeding the performance of existing IPIA detection methods while offering practical deployment advantages. Unlike prevention-focused approaches that require modifications to the underlying LLM architecture, the proposed method operates as a model-agnostic external detection layer with an average inference time of 0.001 ms per sample. This detection-based approach complements existing prevention mechanisms by providing a lightweight, scalable solution that can be integrated into LLM pipelines without requiring architectural changes. Full article
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30 pages, 332 KB  
Review
Prompt Injection Attacks in Large Language Models and AI Agent Systems: A Comprehensive Review of Vulnerabilities, Attack Vectors, and Defense Mechanisms
by Saidakhror Gulyamov, Said Gulyamov, Andrey Rodionov, Rustam Khursanov, Kambariddin Mekhmonov, Djakhongir Babaev and Akmaljon Rakhimjonov
Information 2026, 17(1), 54; https://doi.org/10.3390/info17010054 - 7 Jan 2026
Cited by 20 | Viewed by 36297
Abstract
Large language models (LLMs) have rapidly transformed artificial intelligence applications across industries, yet their integration into production systems has unveiled critical security vulnerabilities, chief among them prompt injection attacks. This comprehensive review synthesizes research from 2023 to 2025, analyzing 45 key sources, industry [...] Read more.
Large language models (LLMs) have rapidly transformed artificial intelligence applications across industries, yet their integration into production systems has unveiled critical security vulnerabilities, chief among them prompt injection attacks. This comprehensive review synthesizes research from 2023 to 2025, analyzing 45 key sources, industry security reports, and documented real-world exploits. We examine the taxonomy of prompt injection techniques, including direct jailbreaking and indirect injection through external content. The rise of AI agent systems and the Model Context Protocol (MCP) has dramatically expanded attack surfaces, introducing vulnerabilities such as tool poisoning and credential theft. We document critical incidents including GitHub Copilot’s CVE-2025-53773 remote code execution vulnerability (CVSS 9.6) and ChatGPT’s Windows license key exposure. Research demonstrates that just five carefully crafted documents can manipulate AI responses 90% of the time through Retrieval-Augmented Generation (RAG) poisoning. We propose PALADIN, a defense-in-depth framework implementing five protective layers. This review provides actionable mitigation strategies based on OWASP Top 10 for LLM Applications 2025, identifies fundamental limitations including the stochastic nature problem and alignment paradox, and proposes research directions for architecturally secure AI systems. Our analysis reveals that prompt injection represents a fundamental architectural vulnerability requiring defense-in-depth approaches rather than singular solutions. Full article
(This article belongs to the Special Issue Emerging Trends in AI-Driven Cyber Security and Digital Forensics)
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