ADC01 – Weak DNS Practices
Introduction DNS is often the unsung hero of application delivery, quietly humming along until something goes wrong. This cornerstone of internet infrastructure translates human readable domain names into machine friendly IP addresses, bridging the gap between users and applications. While vital, DNS frequently gets overlooked, leading to unforeseen performance, availability, scalability, and security issues in application delivery. In today's interconnected world, where seamless application delivery is critical across industries such as finance, healthcare, insurance, telecommunications, hi-tech, energy, government, retail and e-commerce, automotive, and manufacturing, weak DNS practices can wreak havoc. Since stakes are high and user expectations demand near instantaneous responsiveness and reliability, the principles discussed here apply universally. Businesses in any sector must recognize DNS as more than just a basic utility because it is a foundational layer of their application delivery strategy. AI Reference Architecture Use Case example: Enhancing DNS Security and Performance with F5 BIG-IP To better understand how optimized DNS practices strengthen application delivery, let’s consider the following real world use case: Steps in the DNS Optimization Process: Client Initiates DNS Query: A client, located on the external network, initiates a DNS query to resolve a domain name. Query Passes Through F5 BIG-IP: The F5 BIG-IP acts as a secure DNS proxy, validating the query and applying DNSSEC (Domain Name System Security Extensions) for added cryptographic security. DNSSEC ensures that queries are not tampered with and originate from a legitimate source. Authoritative DNS Responds: The validated query is routed securely to the authoritative DNS server cluster within the internal network. The authoritative DNS responds with the appropriate IP address. Response Returned to Client: The optimized, secure response is returned to the client with minimal latency, leveraging DNSSEC and optimized TTL (Time-to-Live) settings for better user experience. This workflow illustrates how incorporating F5 BIG-IP into your DNS architecture can enhance application security, scalability, and performance. Consequences of Weak DNS Practices Impact on Performance DNS inefficiencies are a hidden bottleneck for application performance. In 2023, nearly 27% of user complaints about poor application performance stemmed from DNS related slowdowns (Auvik). When DNS servers aren’t optimized or critical security features like DNS Security Extensions (DNSSEC) are absent, the impact cascades across application performance: Latency increases: Low TTL (Time-to-Live) settings overload DNS servers with repeated queries, slowing down responses for users spread across regions. Vulnerability to hijacking: Without DNSSEC, attackers can intercept or redirect traffic to slower or malicious servers, significantly impacting response times and user experience. Impact on Availability DNS disruptions, either due to attacks or misconfigurations, can lead to major availability issues. For instance: DNS hijacking or cache poisoning: Attackers inject fake records into DNS servers, redirecting users to harmful websites. Without DNSSEC, these vulnerabilities remain exploitable, leading to user mistrust. Low or mismatched TTL settings: These settings exacerbate availability problems by overwhelming DNS servers during failovers or scaling events, making applications inaccessible during critical times. Cloud-based global applications, which rely on dynamic DNS updates to remain accessible, worsen the problem when DNS configurations cannot keep pace with the scaling requirements of infrastructure. Impact on Scalability Scalability is a fundamental goal for any global application. Yet, weak DNS practices create bottlenecks: Dynamic DNS updates: Insecure or improperly authenticated dynamic DNS updates disrupt routing, crippling the application’s ability to handle increased user demand. Unprepared DNS infrastructure: With global audiences and fluctuating traffic volumes, under-provisioned or misconfigured DNS servers can experience elevated latency and outages, hindering business growth and reducing global reach. Impact on Operational Efficiency Operational inefficiencies arise from frequent DNS queries (due to low TTLs) and insecure configurations. IT teams become mired in troubleshooting and responding to incidents like DDoS attacks, instead of focusing on broader strategic goals. Moreover, the resources directed toward mitigating DNS-related issues inflate operational costs unnecessarily, wasting valuable time and money. The Undeniable Need for Best Practices To avoid these pitfalls, organizations need to prioritize robust DNS architectures. Here are key practices to implement: DNSSEC for Security DNSSEC (Domain Name System Security Extensions) operates as a safeguard against cache poisoning and DNS hijacking attacks. Implementing DNSSEC ensures the cryptographic validation of DNS records, mitigating risks from unauthorized changes. This adds a layer of trust and reliability to your DNS infrastructure and by extension to user experiences. DNSSEC is no longer a luxury, but a necessity for securely connecting users across the globe. Optimized TTL Settings for Balance TTL settings determine how long DNS information is cached by resolvers before they query authoritative DNS servers. Too short a value results in frequent DNS lookups, increasing server load and latency. Conversely, excessively long TTL values cause outdated information during dynamic scaling. Organizations should analyze traffic patterns and application behavior to strike the right balance. Regular revisions of TTL settings ensure that user queries are routed efficiently without bottlenecking operations. Secure Dynamic DNS Update Dynamic DNS updates are essential for cloud-based infrastructures where IP addresses frequently change. However, insecure update mechanisms are a gold mine for attackers, providing opportunities to alter DNS records maliciously. By using authentication and encryption mechanisms for DNS updates, organizations can protect records and optimize routing seamlessly. Distributed DNS Architecture Relying on a single DNS service provider or a centralized DNS setup increases the risks of downtime. By spreading DNS across multiple geographically independent providers and locations, organizations ensure better fault tolerance and reliability. Global Implications of Weak DNS In 2023, 90% of organizations faced DNS attacks, with financial losses averaging $1.1 million per incident (EfficientIP). These attacks are not just a cost center but also a real time disruption that tarnishes brand reputation and user trust. Each organization encounters an average of 7.5 DNS attacks annually, underlining the broad spectrum of vulnerabilities across industries. Global operations are particularly susceptible to DNS misconfigurations and weaknesses. Whether through hijacking traffic, launching DDoS campaigns, or exploiting TTL mismanagement, attackers leverage DNS vulnerabilities to cripple applications and compromise sensitive data. To scale securely, organizations need DNS practices aligned with industry standards, steering away from outdated configurations or reliance on "default" infrastructure. Final Thoughts Weak DNS practices are a silent killer of application performance, availability, scalability, and operational efficiency. The good news? These challenges are entirely avoidable. By implementing DNSSEC, optimizing TTL settings, securing dynamic DNS updates, and adopting distributed DNS strategies, organizations can dramatically reduce these risks. In the digital landscape of today, where milliseconds can dictate millions in revenue, DNS cannot be an afterthought. It must be a core pillar of application delivery strategies, ensuring that every user query is answered rapidly, reliably, and securely. DNS influences every aspect of the user experience. It’s the first impression your application makes. Don’t squander it. As your applications scale to meet global demand, strong DNS practices will ensure they deliver consistently, no matter where users click “Buy Now.” Reference Articles Scaling, Securing, and Optimizing DNS Hyperscale and Protect Your DNS While Optimizing Global App Delivery Intelligent DNS Firewall for Service Providers F5 DNS: Global Server Load Balancing The Application Delivery Top 10 ADSP Platform overview AI reference architecture The BIG-IP GTM: Configuring DNSSEC Configuring BIG-IP for Zone Transfer and DNSSEC
Is there a way to have Proactive Bot Defense in Transparent mode (v12)?
I am working on a new DoS profile and would like to not have it block requests but alert on them so I can get a good idea of what configuration tweaks I need to make. Is there any way to only have it alert when it normally would block/CAPTCHA a request that it sees? The current ASM policy is in blocking mode and I would like to keep it that way while the DoS profile is being "tested". Thank you!How to assign a DOS profile to a single URI?
I am in the process of creating a TPS and heavy URL DOS profile for a specific URI on a website (example: ) but do not want it applied to any other part of the even though it is on the same web server. Without using an iRule, is it possible to just assign the DOS profile to /protectme/link? Thank you.
DoS Profile - URL Detection criteria question
Hello, My question is related to the way the F5 detects a DoS when we use the URL detection criteria under the TPS-based anomaly. When calculating the TPS, does it have into account the source IP or it just adds the total of requests for the same URL? From my understanding, if the engine sums all the requests for a URL and the thresholds are reached, then it will start blocking not only the attacker but also legitimate traffic, is this the expected behaviour? On the other hand, how does the DoS engine detect that an attack has finished? Thanks.
F5 Silverline: DDoS Protection and Web Application Firewall as Managed Services
With the growth of cloud services and the software-defined data center, it’s tempting for organizations to embrace self-provisioning and begin to look at everything as a service (-aaS): SaaS, IaaS, PaaS, etc. These days, many companies providing networking solutions are often evaluated based on their ability to craft customized -aaS offerings. There’s certainly much to be admired about the agility and scalability of these –aaS offerings, but they’re not right for every business in every situation. Take, for example, a SaaS offering where the organization purchases a Customer Relationship Management (CRM) software framework that they can then customize to their particular business practices. It’s clean and simple, but what the organization doesn’t get is education on how to configure the software they just purchased –aaS. And if they don’t configure it correctly, they don’t get the full value of the software. F5® Silverline® cloud-based application services are not –aaS offerings, because when an enterprise purchases a subscription to use these services, they also receive support from the F5 experts who manage the services. This allows organizations to rapidly deploy enterprise-grade application services across hybrid environments, while receiving deployment and configuration support every step of the way—without a big upfront investment in IT infrastructure. F5 Silverline DDoS Protection is a service delivered via the Silverline cloud-based platform. It offers multi-layered (L3–L7) protection with cloud-scrubbing technologies to detect, identify, and mitigate threats in real time, returning clean traffic back to the enterprise site. It can run continuously to monitor all traffic and stop attacks from ever reaching the network, or it can be initiated on demand when the site is under DDoS attack. In addition, F5 security experts are available 24/7 to keep business online during a DDoS attack. F5 Silverline Web Application Firewall is a service built on BIG-IP® Application Security Manager® (ASM), which enables organizations to protect against OWASP top 10 threats, application vulnerabilities, and zero-day attacks. Leading Layer 7 DDoS defenses, detection and mitigation techniques, virtual patching, and granular attack visibility thwart even the most sophisticated threats before they reach network servers. BIG-IP ASM is also provided via F5’s Silverline cloud-based application services platform and wholly deployed, set up, and managed by the highly specialized experts in the F5 Security Operations Center (SOC). The members of the F5 SOC team have an unrivalled breadth and depth of industry experience. They use industry-leading F5 products combined with state-of-the-art security tools to ensure the best protection possible for applications. Organizations get the benefit of highly specialized personnel to rapidly deploy application services, but are spared the time and expense of staffing their own specialized team. “F5 Silverline effectively mitigated two recent DDoS attacks,” says a current Silverline customer. “It happened over a weekend and while the security team was notified, they were able to enjoy their weekend. … They [security team] enjoyed the customer experience overall with the Silverline SOC team as they are very responsive; a 5-minute response time.” Silverline DDoS Protection and Silverline Web Application Firewall are not services organizations can find, purchase, configure, and deploy on their own. These services do not empower organizations to do their own DDoS mitigation or make policy changes in the underlying architecture of their web application firewall. That’s what –aaS offerings do: They give organizations the power to do something that they already know how to do. Instead, these managed services leverage the expertise of the F5 SOC team to deliver services that allow organizations to do something they don’t know how to do (like effectively configuring and managing a web application firewall) or are otherwise incapable of doing (like absorb 100+ Gbps attacks). F5 controls the service, the delivery of the service, the features of the service, and the reporting on the service. Instead of granular control over their application services, organizations get the peace of mind that comes from knowing that their web application firewall and DDoS mitigation will work as promised, all the time. “I wanted to be sure to circle back and thank the entire F5 team for your support in enabling our environment to remain processing during a period where the probability of an attack increases exponentially,” says a current Silverline customer. “There is now a greater level of confidence [from multiple teams] we can sustain our business and maintain our customer commitment.” While many security offerings today seem like a self-service buffet, Silverline services more closely resemble a good, old-fashioned insurance policy. Every organization comes under fire at some point. And whether they’re facing a DDoS attack or an application attack, enterprises with Silverline DDoS Protection and Web Application Firewall services are protected anywhere, anytime—no IT security experience required.Comment se protéger des cyberattaques DDOS ?
De nombreux sites Web institutionnels et de Presse Français connaissent actuellement des cyberattaques visant à les rendre indisponibles ou à en défigurer le contenu. Cyberattaques en défiguration Dans le cas d’attaques en défiguration (ou défacement), les cyberattaquants exploitent soit des vulnérabilités des sites web ou de leurs outils de gestion de contenu (CMS) pour en prendre le contrôle afin d’en modifier le contenu. Cyberattaques en DDOS Les attaques en Deni de Service Distribuées ou DDOS ont pour but de saturer les ressources du système d’information de la victime, soit en saturant par exemple les infrastructures et les liens réseaux (attaque dite volumétrique) soit en épuisant la capacité des services applicatifs (attaque dite en épuisement de ressources). Une attaque DDOS n’a pas besoin d’être volumétrique pour faire tomber un site web. Elle peut tout à fait être lente et silencieuse au niveau réseau mais ne toucher que la couche L7 applicative. Techniques d'exploitation des vulnérabilités En résumé, je citerais: Attaque en injection (par exemple sur SQL ou sur le système d’exploitation) visant à exposer les informations confidentielles, à corrompre les données ou à forcer l’interpréteur à exécuter des commandes non désirées. Attaque en Cross-Site Scripting (XSS) qui permet d’exécuter un script dans le but de pirater les sessions web des utilisateurs, défigurer les sites web ou rediriger l’utilisateur vers des sites malicieux. Attaques sur l’authentification, le contrôle d’accès et la gestion de sessions : un système d’authentification ou de gestion de session mal implémenté peut conduire à une compromission de mots de passes, de jetons, de clés de sessions visant à usurper l’identité numérique. Attaque sur les références directes au objets (comme les fichiers, répertoires, clé de base de données, etc) : sans contrôle d’accès ou autre protection, un attaquant peut manipuler ces références afin d’accéder à des données non autorisée. Manipulation des cookies, de paramètres ou des champs cachés. Attaque en Buffer Overflow : Exploitations malicieuses des buffers mémoire pour arrêter des services, avoir les accès au Shell et pour propager des programmes malicieux. Attaque en Cross-Site Request Forgery (CSRF) : qui exploite un accès authentifié en usurpant l’identité d’un utilisateur authentifié. Attaque sur des URLs non restreintes Attaque par dictionnaire sur le contrôle d’accès au système Attaques en déni de service sur la couche 7, attaques en brute force et les attaques de type Web Scrapping. Attaque sur les couches de transport Attaques sur les Redirects ou les Forward non contrôlés. Des projets comme OWASP, WASC ou le SANS font un tour d'horizon des menaces et des techniques d'exploitations. Anatomie d’une cyberattaque sur HTTP ou HTTPS Généralement, une cyberattaque sur un site Web se déroule en 3 étapes : Ciblage et reconnaissance : des robots ou des scripts effectuent des scans pour identifier et récolter des informations sur le site web (les URLs), ses ressources (capacités CPU) ainsi que ses ressources réseaux (bande passante) Sélection des vecteurs d’attaques et exploitation des vulnérabilités Bascule sur une attaque en DDOS si l’exploitation de vulnérabilités ou si le brute force sur le contrôle d’accès n’aboutissent pas. Les contre-mesures Pour les cyberattaques en défiguration, il est possible de les empêcher en appliquant les bonnes pratiques rappelées par l’anssi ainsi que les recommandations sur les contre-mesures ici, tel que la mise en place de pare-feu Applicatif Web (WAF) comme F5 ASM. Comme le rappelle le Gartner, un FireWall réseau ou un IPS ne protègent pas contre les attaques visant les services web. Seul un WAF apporte cette protection. En revanche, il est plus difficile de contrer une cyberattaque DDOS et on ne pourra qu’en atténuer son effet, en absorbant la charge durant l’attaque. Bien sûr, il y a des bonnes pratiques à suivre pour parer aux attaques en DDOS à mettre en place avant l’attaque de façon préventive (l’architecture, la capacité, la détection, etc) mais aussi de façon réactive (l’analyse, les mesures techniques, la reprise sur incident, etc). Dans le scénario d’attaque en déni de service distribué, très souvent quand les mesures techniques sont appliquées durant l’attaque, il est très difficile de différentier les utilisateurs légitimes des attaquants alors le site web est déjà fortement impacté voire déjà tombé. Je vous invite à lire le livre blanc F5 pour atténuer les attaques DDOS. La réponse F5 aux cyberattaques DDOS Face aux cyberattaques DDOS, qu’elles soient de type réseau (L3 / L4), sessions (L5 / L6) ou applicatives (L7), F5 Networks possède la technologie qui permet non seulement d’atténuer ces attaques mais aussi de protéger contre les outils de reconnaissance, les bots et les attaques lentes. La solution de protection anti-DDOS de F5 combine des services à déployer dans le Datacenter (in situ) et dans le Cloud. Le service dans le Cloud appelé Silverline est un service à la demande qui empêche les attaques volumétriques d’atteindre le réseau du Datacenter et fourni une protection anti-DDOS multi-vecteurs et multi-niveaux. Une fois, les attaques volumétriques atténuées, c’est la solution in-situ qui prends le relai pour atténuer les attaques de volume moyen, les attaques sur les sessions (SSL et DNS par exemple) ainsi que les attaques applicatives avancées. Cette solution in-situ fait appel à plusieurs modules F5 : AFM, LTM, GTM et ASM. L’architecture de référence F5 anti-DDOS Elle permet aux administrateurs sécurité réseau d’étendre leurs règles afin d’atténuer les risques d’attaques zéro-day. Cette architecture combine de manière transparente le service F5 Silverline avec les solutions Application Delivery Controller (ADC) de F5 pour offrir la solution de protection DDoS la plus complète. Silverline : un service anti-DDOS à la demande F5 propose différents niveaux de protection, personnalisables en fonction des besoins spécifiques des entreprises et des profils des attaques potentiels : Always On ™ - Première ligne de défense. Cet abonnement permet de bloquer de manière continue le trafic corrompu. Le trafic réseaux du client passe par le service de scrubbing Silverline et seule le trafic légitime est envoyé sur le réseau du client. Always Available ™ - Protection primaire sur demande. Cet abonnement permet de bloquer le trafic malveillant en cas d'attaque. ASM : des protections anti-DDOS avancées A partir de la version 11.6, ASM embarque un mécanisme de défense proactif contre les attaques par des robots web (bot). Il protège contre les attaques en déni de service distribuées (DDoS), le webscrapping, la reconnaissance et les attaques en brute force. Ce mécanisme appelé « Proactive Bot Defense » a pour rôle de compléter les méthodes existantes d’atténuation. Quand cette fonctionnalité est activée, lorsqu’un client accède au site web pour la première fois, le système injecte un challenge Javascript en lieu et place de la réponse initiale, dans le but de valider si le client est un navigateur web légitime ou s’il s’agit d’un robot (bot). Le navigateur web légitime répond au challenge correctement et renvoie la requête avec un cookie signé qu’ASM valide. Il est alors autorisé à accéder au serveur. Parmi les autres techniques de détection de robot web dans ASM, on peut citer les mécanismes de Détection d’activité suspecte clavier et Souris, la Détection de surf rapide. De même, pendant la cyberattaque, ASM active des mécanismes d'atténuation spécifiques comme le Client-Side Integrity Defense ou le Captcha avec du rate limiting en hardware. De la visibilité pendant l'attaque Le graphique ci-dessous montre comment le trafic a été géré par le système, avec des données agrégées et mises à jour toutes les 5 minutes. Un fort pourcentage de requêtes hostiles ont été bloquée conformément à la politique de prévention définie dans le profile DoS. Cette politique utilise du Request Blocking avec du rate limiting basé sur l’URL et l’IP source. Lorsque le trafic est normal, on constate typiquement plus de trafic en passthourgh et moins de trafic bloqué. Pour en savoir plus On organise un Webinar sur le sujet anti-DDOS, le Jeudi 29 Janvier à 11h. Inscriptions ici.
UAE IT Decision-Makers Highlight Growing Scale and Impact of DDoS Attacks
Ahead of tomorrow's IDC CIO summit in Dubai, F5 Networks has released new survey findings highlighting UAE IT decision-makers' views on DDoS attacks. Out of 102 respondents from companies with at least 500 employees, 55% said they had endured a DDoS attack. 13% put the estimated cost of recovery as high as US $ 30 million, 31% put the figure at US$ 20-30 million, and 34% US$10 to 20 million. When asked what the “most disastrous” impact of a DDoS attack would be, 47% of respondents cited the impact on customers. 19% said it would be reputation damage and 14% believed it would be revenue loss. The survey also highlighted the need for greater industry-wide awareness. Only 6% said they could “very accurately” describe the difference between a Layer 3 (network protocol) and Layer 7 (application layer) attacks. 57% said they could do so “somewhat accurately”. F5 Networks is a Gold Sponsor and will take part in a panel discussion focusing on IT security priorities at the IDC CIO Summit 2015, which is held from 25-26 February at Atlantis The Palm, Dubai. The event is held under the patronage of H.E. Sheikh Nahayan Mabarak Al Nahayan Minister of Culture, Youth & Community Development.UAE Cybersecurity Threat Landscape Growing in Intensity and Complexity
Leading UAE IT decision-makers agree that cybersecurity threats are growing in intensity and scale across the region. According to a new survey commissioned by F5 Networks, 81% of surveyed IT decision-makers believed their organisation was more vulnerable than ever to cybersecurity threats. 82% ranked their organisation’s vulnerability to cybercrime, hacking and “hacktivism” as “very” or “extremely” vulnerable, and 79% agreed that it is more difficult than ever to protect their organisations from associated security threats. Worryingly, only 8% are completely confident their organisation has consistent IT security measures across its entire IT network. 34% said their marketing and sales efforts were most vulnerable to attacks, 28% cited email, 27% employee data and 24% customer information.Common cybersecurity threats include distributed denial of service (DDoS) attacks, phishing/spear-phishing emails, data theft, “zero-day” software assaults, web application exploits, and website defacement. The top cybersecurity challenges listed in F5 Networks’s survey include changing motivations for hacking (33% of respondents), the virtualization of server desktops and networks (31%), difficulty in managing a variety of security tools (29%), the increasing complexity of threats (29%), the shift from datacentre-focused infrastructure to the cloud (25%) and the move from traditional client-server applications to web-based applications (24%). In order to adapt and cope, 57% of decision-makers wanted a better understanding of the different types of security threats, 24% called for consolidated management of their different security tools, and 20% wanted a stronger focus on security issues from management.
