This is a type of attack that is designed to make a server unavailable to its intended users.

The basis for this attack often targets applications like Web Servers (i.e., Windows IIS, Apache, etc…); however, application layer attacks have been evolving to application platforms like WordPress, Joomla, Drupal, Magento, and others.

The goal of application layer attacks is to take out an application, an online service, or a website.

These attacks are usually smaller than the ones we have seen before. Nevertheless, the consequence of an application layer attack can be nefarious, since they can go unnoticed until it is too late to react. That is why they are called “low and slow attacks” or even “slow-rate attacks”. They can be silent and small, especially when compared to network-layer attacks, but they can be just as disruptive.

For example, a small VPS on Linode, Digital Ocean or AWS (Amazon) can easily handle a 100,000 to 200,000 packets per second SYN flood. However, the same server running on a WordPress or Joomla CMS can barely break 500 HTTP requests per second without shutting down. That is why application layer attacks can cause as much damage as a network application attack.

When you think about the amplification effect that we discussed in Section 1.4, even one HTTP request (which an attacker can perform without spending much money or resources) can cause a server to execute a large number of internal requests and load numerous files to create the page.

Application-layer attacks (mostly known as Layer 7 attacks) can be part of attacks which not only target the application, but also the bandwidth and network.

One of the reasons why these attacks are on the rise is that they tend to be less expensive to implement by malicious actors. On an application-layer attack, the amplification is CPU, memory or resource based, not network based.

These attacks are also harder to detect than network-layer attacks.

Pro Tip: Sucuri has developed a robust Website Application Firewall (WAF) solution that impedes DDoS attacks from shutting down your website. We will explain more about the Sucuri Firewall later.

Your devices, such as home routers, can be compromised and act as a botnet for DDoS attacks. We have discovered a number of large-scale DDoS attacks related to IoT devices.

Application Layer Attacks include:

  • Attacks targeting the DNS server:

  • The Domain Name System (DNS) is vital to the website infrastructure. DNS associates information with domain names and they can also be a target of DDoS attacks.

    These attacks use spoofing, reflection, and amplification, which means that a tiny query can be largely amplified in order to result in a much larger response in bytes.

    Botnets are used to send DNS requests. If the attacker wanted to target a DNS server, it would use all the botnet zombies in his network to issue DNS request messages for an amplification record from open recursive DNS servers that translate domain names into IP addresses. When it is a new request, the server promptly issues its own request to an infected server with a view to obtain the amplification record. This attack is completed using spoofing so that even though the server has never sent a request, it has been overburdened with responses.

    These attacks are very popular today. They occur at Layers 3 / 4, using publicly accessible DNS servers around the world to overwhelm your web server with DNS response traffic. Your web server is overwhelmed by the influx of responses in turn making it difficult to function as its resources are depleted, making it impossible to respond to legitimate DNS traffic.

    A Layer 3 DNS Amplification is a type of DDoS attack where the attacker hides the origin of the attack from the targeted site by reflecting the attack off of a third party. It uses amplification, meaning that the victim receives more byte counts than what is being sent from the attacker, increasing the power of the attack.

    If these attacks are successful, the targeted site will go down and be unavailable.

  • Layer 7 HTTP Flood – Cache Bypass:

  • Layer 7 HTTP Flood – Cache Bypass is the smartest type of attack. The attackers try to use URLs that cause the most damage making the site use up all of its resources without being cached. For example, an attack can do random dictionary searches for “news”, “gov”, “faith”, which will consume a lot from the site and will not easily be detected since it looks like a normal user’s search habits.

  • Layer 7 HTTP Flood Attack:

  • A Layer 7 HTTP Flood Attack is a type of DDoS attack made to overload specific parts of a site or server. They are complex and hard to detect because the sent requests look like legitimate traffic. These requests consume the server’s resources causing the site to go down. These requests can also be sent by bots, increasing the attack’s power.

    An interesting point about layer 7 DDOS attacks, aka HTTP flood attacks, is that they have little dependency on bandwidth allowing them to easily take down a server by overloading its resources. Depending on the web server and application stack, even a low number of requests per second can choke the application and backend databases. On average, attacks greater than 100 requests per second have the potential to bring down most mid-sized websites.

    The issue with this type of attack is that server-level caching is unable to stop it. The incoming URLs are dynamic and the application forces a reload of the content from the database for every new request that is not in cache, which creates a new page. Attackers know this, making it the preferred method of attack for today’s Layer 7 DDoS attacks.

We categorize the HTTP Floods (Layer 7 DDoS attempts) into 4 major categories:

  • Basic HTTP Floods: Common and simple attacks that try to access the same page over and over. They generally use the same range of IP addresses, user agents, and referrers.

  • Randomized HTTP Floods: Complex attacks that leverage a large pool of IP addresses and randomized the URLs, useragents and referers used.

  • Cache-bypass HTTP Floods: A sub-category of the randomized HTTP Floods that also try to bypass web application caching.

  • WordPress XMLRPC Floods: A sub-category that uses WordPress pingback as a reflection for the attacks.

Any WordPress site with pingback enabled, which is on by default, can be used in DDoS attacks against other sites.

XMLRPC is used for pingbacks, trackbacks, remote access via mobile devices and many other features. However, it can also be heavily misused by attackers.

What can happen is that other WordPress sites can send random requests at a very large scale and bring a website down.

One attacker can use thousands of clean WordPress installations to perform a DDoS attack with a simple pingback request to the XML-RPC file. In other words, a simple command in Linux can start a mammoth attack.

If you are interested in learning more about legitimate WordPress websites being abused in order to perform a DDoS attack, read this blog article: More Than 162,000 WordPress Sites Used for Distributed Denial of Service Attack.

Which of the following usually happens in a malicious denial of service attack?

Which of the following usually happens in a malicious denial-of-service attack? a hacker floods a web server which millions of bogus service requests. You just studied 39 terms!

What is the term used to describe the activity of a cybercriminal?

ransomware. This type of threat is a highly targeted, sophisticated attack on a company with the purpose of gaining access to sensitive information. Select one: a.

Which type of malware demands payment from a user before restoring his/her data?

Ransomware is a form of malware that encrypts a victim's files. The attacker then demands a ransom from the victim to restore access to the data upon payment.

Which term refers to the practice of modifying game software or hardware?

Terms in this set (48) Computer hacking. refers to the practice of modifying or altering computer software and hardware to accomplish a goal that is considered to be outside of the creator's original objective.