Denial of Service attacks are perpetrated by hackers to render services inaccessible to their intended target, often by flooding network devices with data packets or connections requests in large volumes.
Distributed Denial of Service (DDoS) attacks may involve coordinated activity from several systems, making it harder to recognize and stop them. Furthermore, attackers often falsify IP sender addresses, further complicating attempts to block malicious traffic.
Flooding
DoS attacks work by flooding bandwidth with network packets to deny access to a targeted system, often through flooding a server with SYN flood requests that never complete handshake. As a result, the server becomes overwhelmed with unassembled packets that cannot process legitimate requests and becomes inoperable.
An attacker can alter how packets are disassembled, which causes servers to expend their resources trying to reassemble usable information from it. Another type of DoS attack involves misconfiguration of network infrastructure devices like routers or wireless access points (WAPs) so as to redirect network traffic toward specific targets – using either ICMP floods leveraging misconfigured networks, SYN/UDP floods with random source address spoofing to increase attacks or any combination thereof.
Some attacks aim to overwhelm network protocols and servers by flooding them with fake traffic generated through exploits; other attacks such as buffer overflow exploits rely on exploiting weaknesses to fill their memory with data that overwhelms systems, stopping them from operating as expected or designed.
Other attacks aim to overwhelm a server’s available incoming network connections, for example through SYN flood attacks that utilize every available connection and prevent users and systems from creating new ones. This can range from minor disruption to outright system crashes.
Criminal perpetrators may be motivated by revenge, blackmail or hacktivism as well as by warfare motivations. A recent report by the European Union Agency for Cybersecurity showed that 66% of DoS attacks were political in nature based on public information on targets, motivations and goals associated with each DoS attack.
Fragmentation
Fragmentation is the practice of breaking files down into individual non-contiguous blocks and storing them on storage media. While fragmentation can boost system performance by decreasing seeking times on hard disk drives or solid state drives (SSD), it can also negatively impact performance by forcing the operating system to search and retrieve individual fragmented file blocks instead of accessing contiguous blocks at once.
Fragmented files require more time to store and access, with fragmentation potentially overwhelming caches more quickly and resulting in CPU usage that exceeds memory limits, potentially significantly slowing system speed and efficiency.
Application-targeted DoS attacks exploit vulnerabilities in specific applications to render them unusable or unstable, often by sending input which exploits bugs within them and causes crashes or instability in them. Such an attack can have severe repercussions for an organization and be difficult to mitigate without investing heavily in new technology.
DoS (Denial-of-Service) attacks can disrupt business services and damage an organization’s reputation, potentially impacting customers, investors and partners. To combat and respond to DoS attacks effectively, organizations should first establish what normal network activity looks like over an extended period – this will help identify any suspicious traffic patterns which might indicate an attempted DoS attack.
Some DDoS attacks use a network of computers infected with malware to initiate an overwhelming flood of meaningless online requests that overwhelm servers, rendering them unavailable or slow to respond to legitimate ones. DDoS attacks can be particularly difficult to defend against and can have lasting repercussions for companies that fall prey. Therefore, DDoS attacks have become an increasing target. Organizations seeking to defend against DDoS attacks should adopt technologies designed to monitor their entire infrastructure and respond quickly and comprehensively, including DDoS mitigation tools, dedicated security teams and emergency response plans.
Spoofing
Attackers can manipulate network packets to make it appear they come from their target source, then direct these fake packets towards it, overloading servers with traffic and blocking legitimate users from access. Spoofed attacks can be difficult for cyber security teams to uncover and stop due to relationships among many Internet service providers who host multiple servers and hosts; such arrangements amplify these attacks by sending intermittent bursts of faked traffic that appear as though it comes from those sources.
An alternative DoS attack involves directly assaulting the host or system rather than overwhelming it with illicit traffic. This form of DoS strike attacks specific systems and functions integral to target functionality; such as memory, CPU power or disk space usage and system crashes. Attackers could then attempt to seize this opportunity in order to cause system-wide outages.
Attackers may spoof the MAC address of a host to make it appear as the source of an attack, then use a program to send Internet Control Message Protocol packets bearing their IP addresses that look legitimate, making the victim think they’re receiving responses from a legitimate source and draining its resources.
Attackers may encumber network infrastructure that connects a target machine to other devices on its same network, preventing legitimate users from gaining entry and rendering the target system completely useless.
This can often be accomplished using a SYN flood attack. This technique sends requests that don’t complete a full three-way handshake to their target, flooding all available connections and leaving none for future requests.
Teardrop attacks directly target infrastructure itself, such as taking advantage of vulnerabilities in TCP/IP internet protocol suite to send fragmented packets that overwhelm servers until they cannot reassemble original data, which often leads to their collapse.
DoS attacks can be particularly devastating to organizations and businesses, wreaking havoc by slowing down services or completely shutting them down, with massive disruption and millions of dollars lost revenue as a result. For this reason, businesses should implement the most secure technology possible and partner with an expert cybersecurity firm to defend them against DoS attacks and other cyber threats.
Man-in-the-Middle Attacks
An attack utilizing Man-in-the-Middle tactics seeks to disrupt service by intercepting and altering data transferred between two parties. An attacker could accomplish this through exploiting security holes present in systems like unprotected Wi-Fi networks and public hotspots or through malware infections.
DoS attacks that use source address spoofing to route network packets randomly can be difficult to detect and mitigate, leading the targeted server to be overwhelmed by requests that it can never process and which block legitimate requestors from connecting. Network telescopes may help detect such attacks by looking for backscatter from victims trying to communicate with attackers.
SYN flood attacks are one form of DoS attacks that involve sending multiple fake requests at once to a target server from one computer, designed to overwhelm it and force it into slowdown or crash mode, as well as flood the affected ports with fake requests from fake sources, making them unavailable for legitimate requests. Attackers use various techniques for these attacks such as sending multiple requests rapidly or forgerying source addresses of each request sent out.
Cybercriminals frequently employ multiple devices under their control in a coordinated DoS attack known as a botnet, an intricate network of personal computers and other connected devices infected with malware, to launch coordinated DoS attacks against their targets. Together these resources are combined to send massive traffic requests towards one server at once.
DoS attacks represent a constant danger for businesses of all sizes and across industries, regardless of industry sector. DoS attacks can threaten productivity and revenue loss for any number of reasons ranging from blackmail or hacktivism to criminal threats such as ransomware. An effective cybersecurity architecture is key to safeguarding against DoS threats that threaten operations of any size and nature.
Start by developing an incident response plan and identifying your enterprise’s vulnerable systems, processes and points of contact. Make sure you have backup copies of all data regularly tested; incorporate a monitoring service capable of alerting you of DoS attacks; and consider contracts with Internet or cloud service providers that specialize in protecting against these types of attacks.
