What are the most effective ways to conduct a large-scale network vulnerability assessment?

The scope is just the entire network and it is all the way from access, distribution and core layers in branch and campus networks to WAN and data centers, external connectivity to vendors, partners, cloud… all are included in scope. Scope includes different hardware, software, protocols, features and every aspect of the network. Important part is the process of identifying the vulnerabilities and remediating the same.

Begin by gaining a comprehensive understanding of the size and scale of assets through thorough asset inventory considerations. Next, utilize automated scanning as a tool to identify vulnerabilities. Prioritize vulnerabilities, starting with major and high-risk categories. Implementing a patch management solution not only reduces administrative effort but also enhances patching accuracy. Penetration testing is a crucial step to evaluate the effectiveness of our response in the preceding steps. Lastly, running periodic scans is essential to ensure that vulnerabilities have been addressed and to assess ongoing security measures

To effectively conduct a large-scale network vulnerability assessment, start with planning and defining the scope, including legal compliance. Create a detailed inventory of all network components. Utilize vulnerability scanning tools for identifying known issues, and conduct penetration testing to simulate real-world attacks. Assess risks based on potential impact and prioritize them. Develop a remediation plan, focusing on immediate risks. Ensure continuous monitoring and regular reassessment to adapt to new threats. Document findings and remediation steps, and report to relevant stakeholders. Train employees on security best practices and stay informed about emerging cybersecurity threats.

Fundamental definir el alcance del análisis, yo recomiendo hacer un barrido general para levantar el entorno al que nos enfentamos, luego identificar junto al cliente los segmentos de red criticos y partir por ahi levantando servicios y a partir de ahí, cerrar puertos innecesarios. una vez acotada la red de servicios, empezaria por controlar endpoints y dispositivos IoT. por supuesto que segmentar la red es crucial.

One effective way to conduct vulnerability management in large networks is to use platforms that are using passive scanning with intelligence asset detection capability. Perform traffic capturing at the main points (core part) of the network where the networks are interconnected, then send captured traffic to such platforms which are able to recognize the asset, vendor, OS, etc.

Básicamente, para comenzar se requiere un analizador de tráficoy un analizador de puertos. con esto podremos mapear efectivamente la red, luego podremos contrastar con la informacion disponible del cliente, con Wireshark y Nmap ya podemos partir.

A escolha das ferramentas e técnicas certas é crucial para uma avalia??o de vulnerabilidade de rede eficaz. Considere diversos fatores, como precis?o, confiabilidade, velocidade, eficiência, compatibilidade, custo e impacto. Use uma combina??o de ferramentas para uma avalia??o abrangente.

In my experience, I have seen cases where a tool used in scanning actually brought down a service by overwhelming the server with a wave of test payload that the server succumbs to DOS. Therefore, knowing the property and behavioral pattern of operation of individual tools is essential.

Select vulnerability scanners, intrusion detection/prevention systems (IDS/IPS), and penetration testing tools appropriate for your environment. Consider internal and external scanning to cover all attack vectors.

Il est important de déterminer en amont le budget et le temps qui seront alloués à l'évaluation de la vulnérabilité du réseau et des systèmes associés. C'est principalement en fonction de ces critères qu'il sera alors possible de définir quels sont les outils les mieux adaptés au besoin. Il existe de très nombreux outils d'audit, et le temps d'adaptation nécessaire à leur ma?trise est un facteur non-négligeable, aussi si vous n'êtes pas un spécialiste faites plut?t appel à des professionnels : le gain de temps et la fiabilité des résultats devraient facilement vous convaincre d'externaliser ce type de services.

Plan scan times to minimize disruption and network load. Schedule regular scans for continuous monitoring and consider additional scans after system updates or significant configuration changes.

Commencez par définir une fenêtre de temps pour effectuer vos tests sans nécessairement perturber vos différents services. Analysez les résultats immédiats de vos tests, mais pensez également à la veille continue : des outils automatisés d'analyse et de reporting existent pour vous faciliter la tache (Splunk, Stack ELK, etc.) L'inscription à un programme de bugbounty est également un bon complément : la communauté des hackers éthiques peut vous aider efficacement à identifier les vulnérabilités de vos infrastructures, à moindre co?t (vous ne payez que si la faille de sécurité est avérée).

Realizar varreduras e testes é uma etapa crítica na avalia??o de vulnerabilidade de rede em larga escala. Certifique-se de seguir as práticas recomendadas e diretrizes para realizar essas atividades com eficiência e seguran?a.

Regular scan , continue monitoring and double check, always prefer scan schedule,scan schedule and verify the network load check-up

All stakeholders, especially disaster recovery and incidence response team needs to be properly informed and debriefed before and during the scanning process. They must well informed and be on standby to restore services to normal incase of an outage during a scan. Also, a realtime communication channel should be opened between the assessors and the incidence response team for quick turnaround time and to avoid communication loop.

Analyze and prioritize is most important part of the assessment This is applicable not only from security perspective but also from business.

Validate Scan Findings: False positives are common, so verify identified vulnerabilities manually to avoid wasting resources on unnecessary remediation efforts. Risk Assessment: Evaluate the severity of each vulnerability based on its exploitability, potential impact, and existing patches. Prioritize remediation efforts based on the highest risk vulnerabilities. Reporting and Communication: Clearly communicate the assessment findings to stakeholders, highlighting critical vulnerabilities and recommended remediation actions.

Factors like level of exposure, CVSS scores, publicly available exploit, criticality of affected assets among others are indicators of the analysis. This indicators are used to determine the priority of findings and the strategy for mitigation and remediation. I believe different organizations have different approaches they use to rank and prioritizing results. There’s no one for all approach.

Organizations can enhance their overall cybersecurity posture by conducting effective large-scale network vulnerability assessments through a combination of automated tools, manual testing, risk prioritization, and ongoing monitoring. It is crucial to regularly repeat the assessment process in order to adapt to evolving security threat.

Executive Summary: A concise overview of the assessment, key findings, and recommendations. Methodology: A description of the methods used to conduct the assessment. Results: A detailed presentation of the findings, including data visualizations, charts, and tables. Analysis: An interpretation of the results and their implications for the subject of the assessment. Recommendations: Actionable steps that can be taken based on the findings. Conclusion: A summary of the report's key points and next steps.

L'évaluation de la vulnérabilité du réseau est inutile sans une bonne remédiation : rien de pire que de se savoir vulnérable sans mettre en ?uvre les moyens nécessaires à la correction du problème. Chaque vulnérabilité avérée mérite un suivi complet et bien organisé, de nombreux outils (libres ou payants) de type "ticketing" existent pour réussir à assurer ce tra?age. Plus que nécessaire, en cas de litige au niveau juridique, il vous faudra être capable de montrer que vous avez mis en ?uvre tous les moyens nécessaires pour protéger les données de vos clients et/ou collaborateurs dès lors que la vulnérabilité mise en cause aura été identifiée.

Consider the vulns in the context of the environment they are in - many airgapped OT Networks, such as Railway or Transport, have built in real-world deterrents (i.e. wanting to live and not get hit by a train) making some exploits more likely in their context than others (i.e. it's more likely a central office or Data Centre hub port will get popped than a trackside access switch). Business context is as important to a vulnerability assessment as raw CVE opinionated scoring, if not more; not every business follows the idealised CVE risk model.