Pejman Najafi

dblp:218/8812 · DBLP profile ↗
← Back
9ranked-venue papers
6as first author
7since 2021 · last 2026
0000-0003-3171-2185ORCID · corroborated

Domains — the database's venue-derived domains; a paper can count in several

Security and privacy · 6 · 5 first-author · 4 since 2021Artificial intelligence and machine learning · 2 · 2 since 2021Computer networks · 1 · 1 first-author · 1 since 2021Databases, data management, data science and information retrieval · 1 · 1 since 2021Applied, interdisciplinary, general and emerging computing · 1 · 1 since 2021
YearPublicationVenuePosition
2026 When Prompts Become Payloads: A Framework for Mitigating SQL Injection Attacks in Large Language Model-Driven Applications
abstract
Natural language interfaces to structured databases are becoming increasingly common, largely due to advances in large language models (LLMs) that enable users to query data using conversational input rather than formal query languages such as SQL. While this paradigm significantly improves usability and accessibility, it introduces new security risks, particularly the amplification of SQL injection vulnerabilities through the prompt-to-SQL translation process. Malicious users can exploit these mechanisms by crafting adversarial prompts that manipulate model behavior and generate unsafe queries. In this work, we propose a multi-layered security framework designed to detect and mitigate LLM-mediated SQL injection attacks. The framework integrates a front-end security shield for prompt sanitization, an advanced threat detection model for behavioral and semantic anomaly identification, and a signature-based control layer for known attack patterns. We evaluate the proposed framework under diverse and realistic attack scenarios, including prompt injection, obfuscated SQL payloads, and context-manipulation attacks. To ensure robustness, we generate and curate a comprehensive benchmark dataset of adversarial prompts and assess performance across a fine-tuned LLM configuration. Experimental results demonstrate that the proposed approach achieves high detection accuracy while maintaining low false-positive rates, significantly improving the secure deployment of LLM-powered database applications.
Farzad Nourmohammadzadeh Motlagh, Mehrdad Hajizadeh, Mehryar Majd, Pejman Najafi, Feng Cheng 0002, Christoph Meinel
ICAART (2)4
2025 Large Language Models in Cybersecurity: State-of-the-Art
Farzad Nourmohammadzadeh Motlagh, Mehrdad Hajizadeh, Mehryar Majd, Pejman Najafi, Feng Cheng 0002, Christoph Meinel
ICISSP (2)4
2024 HEOD: Human-assisted Ensemble Outlier Detection for cybersecurity
Pejman Najafi, Feng Cheng 0002, Christoph Meinel
Comput. Secur.1
2024 You are your friends: Detecting malware via guilt-by-association and exempt-by-reputation
Pejman Najafi, Wenzel Pünter, Feng Cheng 0002, Christoph Meinel
Comput. Secur.1
2022 A Comprehensive Review of Anomaly Detection in Web Logs
abstract
Anomaly detection is a significant problem that has been researched within diverse research areas and application domains, especially in the area of web-based internet services or cybersecurity. Many anomaly detection techniques have been developed for specific application domains, while others are more generic. The Log files of Web-server give insight into the state of web-server and applications running on it and enable the detection of abnormal incidents or behavior. This paper focuses on particularly web-server HTTP logs to the problems of Web-server Log Anomaly Detection (WLAD) due to their own nature and features and aims to provide a brief review of different Data-driven techniques to get to the bottom of recent studies and developments made in the context of WLAD. Moreover, in this paper, the literature related to webserver logs analysis, as well as other closely related to the WLAD topic, are taken into consideration for review. We have classified existing techniques into different categories based on the underlying approach adopted. When applying a particular technique, these assumptions can be used as guidelines to assess the method’s effectiveness in this area. We also provide a basic security anomaly detection approach for each category and compare the existing methods as variants of the basic technique. Further, we identify the cons and pros of the current practices for each category. We also discuss the computational complexity of the methods, which is an essential issue in the domain of Big Data.
Mehryar Majd, Pejman Najafi, Seyed Ali Alhosseini, Feng Cheng 0002, Christoph Meinel
BDCAT2
2021 NLP-based Entity Behavior Analytics for Malware Detection
abstract
In this research, we formulate malware detection as a large-scale data-mining problem within Security Information and Event Management (SIEM) systems. We hypothesize that behavioral analysis of executable/process activities, such as file reads/writes, process creations, network connections, or registry modifications, enables the detection of advanced stealthy malware. To achieve this detection, we model processes behaviors as a set of directed acyclic graph streams and identify outliers in the set of graph streams. We enable this detection by conversion of the behavioral graph streams into documents, embedding using state-of-the-art Natural Language Processing model, and eventually performing novel outlier detection on the high dimensional vector representation of the documents. We evaluate our approach in a real-world setting, next to the SIEM system of a large-scale international enterprise (over 3TB of EDR logs). The proposed method has shown the capability to detect previously unknown threats.
Pejman Najafi, Daniel Köhler, Feng Cheng 0002, Christoph Meinel
IPCCC1
2021 SIEMA: Bringing Advanced Analytics to Legacy Security Information and Event Management
Pejman Najafi, Feng Cheng 0002, Christoph Meinel
SecureComm (1)1
2019 MalRank: a measure of maliciousness in SIEM-based knowledge graphs
abstract
In this paper, we formulate threat detection in SIEM environments as a large-scale graph inference problem. We introduce a SIEM-based knowledge graph which models global associations among entities observed in proxy and DNS logs, enriched with related open source intelligence (OSINT) and cyber threat intelligence (CTI). Next, we propose MalRank, a graph-based inference algorithm designed to infer a node maliciousness score based on its associations to other entities presented in the knowledge graph, e.g., shared IP ranges or name servers.
Pejman Najafi, Alexander Mühle, Wenzel Pünter, Feng Cheng 0002, Christoph Meinel
ACSAC1
2017 Guilt-by-Association: Detecting Malicious Entities via Graph Mining
Pejman Najafi, Andrey Sapegin, Feng Cheng 0002, Christoph Meinel
SecureComm1