In computing, a denial-of-service attack ( DoS attack ) is a cyber attack in which the offender attempts to create a machine or network resource unavailable to the intended user temporarily or without the disruptive limit of the service from the host connected to the Internet. A denial of service is usually done by flooding a targeted machine or resource with excessive demand in an attempt to overload the system and prevent some or all legitimate requests from being met.
In distributed denial-of-service attacks ( DDoS attacks ), incoming traffic flooded victims from many different sources. This effectively makes it impossible to stop an attack by simply blocking a single source.
DoS or DDoS attacks are similar to a group of people clustered at the entrance of a store, making it difficult for legitimate customers to enter, disrupting trade.
Criminal offenders of DoS attacks often target sites or services hosted on high profile web servers such as banks or credit card payment gateways. Revenge, extortion and activism can motivate these attacks.
Video Denial-of-service attack
History
Court testimony shows that the first demonstration of the DoS attack was made by Khan C. Smith in 1997 during the DEF CON event, disrupting Internet access to the Las Vegas Strip for over an hour. The release of sample code during the event led to Sprint's online attacks, EarthLink, E-Trade, and other large companies in the coming year.
On March 5, 2018, the US-based service provider became the largest DDoS victim in history, peaking at around 1.7 terabits per second.
Maps Denial-of-service attack
Type
Denial-of-service attacks are characterized by explicit attempts by attackers to prevent the legitimate use of a service. There are two common forms of DoS attacks: the collision service and the flood service. The most serious attacks are distributed.
Distributed DoS
A distributed denial-of-service ( DDoS ) is a large-scale DoS attack in which the offender uses more than one unique IP address, often thousands of them. Since incoming traffic flooded victims from multiple sources, it is not possible to stop attacks by simply using incoming filtering. It also makes it very difficult to distinguish legitimate user traffic from attack traffic when scattered at many points of origin. As an alternative or augmentation of DDoS, an attack may involve forging a sender's IP address (IP spoofing address) further complicating identification and defeating an attack.
The scale of DDoS attacks has steadily increased over the past few years, by 2016 exceeding terabits per second. Some common examples of DDoS attacks are fraggle, smurf, and SYN flooding.
Application layer attack
A DDoS attack application layer (sometimes referred to as layer 7 DDoS attack ) is a form of DDoS attack in which the attacker is targeting the application layer of the OSI model. Attack too many perform certain functions or features of the website with a view to disable the function or feature. These application layer attacks are different from overall network attacks, and are often used against financial institutions to distract IT personnel and security from security breaches. In 2013, DDoS application layer attacks represent 20% of all DDoS attacks. According to a study by the Akamai company, there are "51 percent more application layer attacks" from Q4 2013 to Q4 2014 and "16 percent more" than Q3 2014 during Q4 2014. In November 2017; Junade Ali, a Computer Scientist at Cloudflare notes that while network-level attacks continue to be high-capacity, they are rare. Ali further noted that although network-level attacks became less frequent, data from Cloudflare showed that application-layer attacks still showed no signs of slowing.
Application layer
The Open Systems Interconnection Model (OSI) (ISO/IEC 7498-1) is a conceptual model that characterizes and standardizes the internal function of a communication system by partitioning into an abstraction layer. This model is a product of the Open Systems Interconnection project at the International Organization for Standardization (ISO). The model groups similar communication functions into one of seven logical layers. The coating serves a layer on it and is presented by a layer beneath it. For example, a layer that provides error-free communication across the network provides the path required by the application on it, while the next lower layer for sending and receiving packets that form the content of the path. Two instances on one layer are connected by a horizontal connection to that layer.
In the OSI model, the application layer's definition is narrower in scope than is often applied. The OSI model defines the application layer as the user interface. The OSI application layer is responsible for displaying data and images to users in a human-recognizable format and to interface with the presentation layer underneath. In implementations, application and presentation layers are often combined.
Attack method
A DDoS application layer attacks are performed primarily for specific targeted purposes, including interrupt transactions and access to databases. This requires fewer resources than network layer attacks but often accompanies them. Attacks are disguised to look like legitimate traffic, unless they target a specific app package. Attacks on the application layer may interfere with services such as information retrieval or search functionality as well as web browser functionality, email services and photo apps. To be considered a distributed denial of service attack , more than about 3-5 nodes on different networks should be used; using fewer nodes qualifies as a DoS attack but not a DDoS attack.
Continued DoS persistent
A advanced persistent DoS (APDoS) is more likely to be performed by persistent persistent threats (APT): attackers who have good resources, are highly skilled and have access to resources and capacity of commercial-grade computers substantially. The APDoS attack represents a clear and emerging threat that requires special incident monitoring and response services as well as the defensive capabilities of a DDoS dedicated mitigation service provider.
This type of attack involves large DDoS network layer attacks through a flooded application layer (HTTP) flood, followed by repetitive (at varying intervals) SQLi and XSS attacks. Typically, offenders can simultaneously use from 2 to 5 attack vectors involving up to several tens of millions of requests per second, often accompanied by massive SYN floods that not only can attack the victim but also every service provider that implements all kinds of DDoS-managed mitigation capabilities. These attacks can last for several weeks. The longest period continuously recorded so far lasts 38 days. This attack involves about 50 petabits (50,000 terabit) of malicious traffic.
Attackers in this scenario may tactically switch between multiple targets to create redirects to avoid defensive DDoS actions but all temporarily end up focusing the main push of an attack onto a single victim. In this scenario, attackers with ongoing access to some very powerful network resources are able to maintain a prolonged campaign that generates a large degree of DDoS traffic that is not reinforced.
APDoS attacks are characterized by:
- advanced surveillance (pre-attack OSINT and extensive decoyed scanning created to avoid detection for long periods)
- tactical execution (attack with primary and secondary victims but focus on primary)
- explicit motivation (end/end target)
- large computing capacity (access to computer power and large network bandwidth)
- simultaneously multi-threaded OSI layer attacks (advanced tools that operate on layers 3 through 7)
- long-term persistence (incorporating all of the above into a well-managed, integrated attack on various targets). Denial-of-service_as_a_service Denial-of-service as a service
Some vendors provide what is called a "booter" or "suppressor" service, which has a simple web front end, and accepts payments via the web. Marketed and promoted as a stress testing tool, they can be used to conduct unauthorized denial-of-service attacks, and allow technically unsophisticated attackers to access advanced attack tools without the need for an attacker to understand their use. Usually supported by botnets, traffic generated by stress consumers can range anywhere from 5-50 Gbit/s, which can, in most cases, deny average internet access to internet users.
src: msdnshared.blob.core.windows.net
Symptoms
The US Computer Emergency Preparedness Team (US-CERT) has identified denial-of-service attack symptoms to include:
- network performance is very slow (opening file or accessing website)
- unavailability of specific websites
- inability to access any website
- a dramatic increase in the number of spam emails received (this type of DoS attack is considered an e-mail bomb).
Additional symptoms may include:
- disconnection of wireless or wired internet connection
- denial of long-term access to the web or any internet service.
If an attack is performed on a sufficiently large scale, the entire geographical area of ​​Internet connectivity can be compromised without the knowledge or intent of an attacker by improperly or brittle network infrastructure equipment.
src: www.cisco.com
Attack techniques
Various programs are used to launch DoS attacks.
Attack tools
In cases like MyDoom and Slowloris, these tools are embedded in malware, and launch their attacks without the knowledge of the system owner. Stacheldraht is a classic example of DDoS tools. It uses a layered structure in which the attacker uses a client program to connect to the handler, which is a compromised system that issues commands to a zombie agent, which in turn facilitates DDoS attacks. Agents are compromised through handlers by attackers, using automated routines to exploit vulnerabilities in programs that accept remote connections running on the targeted remote host. Each handler can control up to a thousand agents.
In other cases, the machine may be part of a DDoS attack with the owner's consent, for example, in Operation Payback, which is governed by the Anonymous group. LOIC is usually used in this way. Together with HOIC various DDoS tools are available today, including paid and free versions, with various features available. There's an underground market for this in forums related to hackers and IRC channels.
GCHQ UK has tools built for DDoS, named PREDATORS FACE and ROLLING THUNDER.
Application layer flood
Various DoS-causing exploits such as buffer overflow can cause software running a server to be confused and fill up disk space or consume all available memory or CPU time.
Other types of DoS rely primarily on brute power, flood the target with exceptional package flux, oversaturating the connection bandwidth or depleting the target system resources. Bandwith-saturating flooding relies on attackers who have higher bandwidth than victims; the common way to achieve today is through the denial of distributed services, using botnets. Another target of DDoS attacks may be to generate additional costs for application operators, when the latter uses resources based on cloud computing. In this case, it is usually an application that uses resources related to the required Quality of Service level (for example, the response must be less than 200 ms) and this rule is usually associated with automated software (eg Amazon CloudWatch) to increase virtual resources more than the provider in order to meet the QoS level set for increased demand. The main incentive behind the attack may be to encourage application owners to increase the level of elasticity to handle increased application traffic, to cause financial losses or forcing them to become less competitive. Other floods may use package types or special connection requests to saturate limited resources by, for example, by occupying the maximum number of open connections or filling the victim's disk space with logs.
"Banana attack" is another type of DoS. This involves redirecting outgoing messages from clients back to clients, preventing outside access, as well as flooding clients with packets sent. LAND attacks are of this type.
An attacker with shell-level access to the victim's computer can slow it down so that it can not be used or crash it with a fork bomb.
Such an application-level DoS attack is XDoS (or XML DoS) that can be controlled by modern web application firewall (WAFs).
Attack of degradation services
A "throbbing zombie" is a compromised computer directed at launching casualty and short-circuited victim websites with the intention of just slowing it down rather than crashing into it. This type of attack, called "service-degradation" rather than "denial of service", can be more difficult to detect than ordinary zombie invasion and can disrupt and impede connections to websites for long periods of time, potentially causing more disturbance from concentrated flooding. Exposure to service degradation attacks is more complicated by the issue of whether the server is actually attacked or under normal traffic load.
Denial-of-service Level II
The purpose of the L2 DoS attack (possibly DDoS) is to cause the launch of a defense mechanism that blocks the network segment from which the attack originated. In case of a distributed attack or modification of the IP header (which depends on the type of security behavior) it will completely block the network being attacked from the Internet, but without a system crash.
Distributed DoS Attack
Distributed denial-of-service attacks (DDoS) occur when multiple systems are flooded with targeted bandwidth or system resources, usually one or more web servers. Such attacks are often the result of some compromised systems (eg, botnets) flooding targeted systems with traffic. Botnets are zombie computer networks that are programmed to receive commands without the owner's knowledge. When the server is overloaded with a connection, the new connection is no longer acceptable. The main advantage for attackers using distributed denial-of-service attacks is that some machines can generate more attack traffic from one machine, some attack engines are more difficult to shut down than one attack machine, and that the behavior of each attack machine can be more hidden- hidden, making it more difficult to track and close. The advantage of this attacker poses a challenge to the defense mechanism. For example, simply buying more incoming bandwidth than the current attack volume may not help, since an attacker might just be able to add more attackers. This, after all, will end up completely destroying the website for a period of time.
Malware can carry DDoS attack mechanism; one of the more famous examples of this is MyDoom. His DoS mechanism is triggered at a certain date and time. This type of DDoS involves the hardcoding of the target IP address prior to the release of malware and no further interaction is required to launch the attack.
A system can also be compromised with a trojan, allowing an attacker to download a zombie agent, or a trojan may contain one. Attackers can also break into systems using automated tools that exploit vulnerabilities in programs that listen to connections from remote hosts. This scenario mainly concerns the system acting as a server on the web. Stacheldraht is a classic example of DDoS tools. It uses a layered structure in which the attacker uses a client program to connect to the handler, which is a compromised system that issues commands to a zombie agent, which in turn facilitates DDoS attacks. Agents are compromised through handlers by attackers, using automated routines to exploit vulnerabilities in programs that accept remote connections running on the targeted remote host. Each handler can control up to a thousand agents. In some cases, the machine may be part of a DDoS attack with the owner's consent, for example, in Operation Payback, which is governed by the Anonymous group. These attacks can use different types of internet packages such as: TCP, UDP, ICMP, etc.
This compromise collection system is known as botnets/rootservers. DDoS tools like Stacheldraht still use classic DoS attack methods centering on IP spoofing and amplification like smurf attacks and fraggle attacks (this is also known as bandwidth consumption attacks). SYN Flood (also known as resource starvation attack) can also be used. More recent tools may use DNS servers for DoS purposes. Unlike the DDoS MyDoom mechanism, botnets can be changed against any IP address. The kiddies script uses it to deny the availability of reputed websites for legitimate users. The more sophisticated attackers use DDoS tools for the purpose of blackmail - even against their business rivals.
Simple attacks such as SYN floods can appear with multiple sources of IP addresses, providing a well distributed DoS view. These flood attacks do not require completion of a TCP three way handshake and attempt to spend the destination SYN queue or server bandwidth. Because source IP addresses can be skipped negatively, attacks can come from a limited set of sources, or even from a single parent. The addition of stacks such as syn cookies can be an effective mitigation of the SYN queue flood, but complete bandwidth fatigue may require engagement.
If an attacker mounts an attack from one host then it will be classified as a DoS attack. In fact, any attack on availability will be classified as a denial-of-service attack. On the other hand, if an attacker uses multiple systems to simultaneously launch attacks against a remote host, this would be classified as a DDoS attack.
It has been reported that there are new attacks from the internet of things that have been involved in denial of service attacks. In one recorded attack it peaked around 20,000 requests per second coming from about 900 CCTV cameras.
GCHQ UK has tools built for DDoS, named PREDATORS FACE and ROLLING THUNDER.
DDoS extortion
By 2015, DDoS botnets such as DD4BC grow to prominence, targeting financial institutions. Cyber-exploiters usually begin with low-level attacks and warnings that larger attacks will be made if ransom is not paid in Bitcoin. Security experts recommend websites targeted not to pay a ransom. The attackers tend to get into the extortion scheme extended after they recognize that the target is ready to pay.
HTTP POST DoS Attack
First discovered in 2009, the HTTP POST attack sends a complete and legitimate HTTP POST header, which includes the 'Content-Length' field to determine the body size of the messages to be followed. However, the attacker then sends to the actual message body at a very slow rate (eg 1 byte/110 second). Since all messages are correct and complete, the target server will try to comply with the Content-Length field in the header, and wait for the entire contents of the message to be sent, which can take a very long time. Attackers assign hundreds or even thousands of such connections, until all resources for incoming connections on the server (the victim) run out, thus making further connections (including legitimate) impossible until all data has been transmitted. It should be noted that unlike many other DoS attacks (D), which attempt to subdue the server by overloading its network or CPU, the HTTP POST attack targets the logical source of the victim, meaning the victim will still have network bandwidth enough and processing power to operate. Further combined with the fact that Apache will, by default, receive requests up to 2GB in size, this attack can be very powerful. HTTP POST attacks are difficult to distinguish from legitimate connections, and are therefore capable of passing multiple protection systems. OWASP, open source web application security project, has released a testing tool to test the server's security against this type of attack.
Internet Message Messaging Protocol (ICMP) flooded
Smurf attacks rely on misconfigured network devices that allow packets to be sent to all host computers on a given network via broadcast address of the network, rather than certain machines. The attacker will send a large number of IP packets with the counterfeit source address to appear as the victim's address. Most devices on the network will, by default, respond to this by sending a reply to the source IP address. If the number of machines on the network receiving and responding to these packets is very large, the victim's computer will be flooded with traffic. This overloads the victim's computer and can even make it unusable during the attack.
Ping flood is based on sending a large number of ping packets, typically using the "ping" command from a Unix-like host (the -t flag on a Windows system is much less capable of flooding the target, nor -l (size) flags do not allow larger packet size sent of 65500 in Windows). Very easy to launch, the main requirement is access to greater bandwidth than the victim.
Ping's death is based on sending the wrong ping packet victim, which will cause the system crashes on the vulnerable system.
The BlackNurse attack is an example of an attack that takes advantage of the required ICMP Destination Port Unreachable package.
Nuke
Nuke is an old denial-of-service attack against a computer network consisting of a split or invalid ICMP packet sent to the target, achieved by using a modified ping utility to repeatedly send this corrupted data, slowing down the affected computer until it arrives to stop completely.
A specific example of a well-known nuke attack is WinNuke, which exploits a vulnerability in the NetBIOS handler in Windows 95. An out-of-band data string is sent to TCP port 139 from the victim's computer, causing it to lock and display Blue Screen of Death (BSOD).
Peer-to-peer Attack
Attackers have found a way to exploit a number of bugs on peer-to-peer servers to launch DDoS attacks. The most aggressive peer-to-peer-DDoS attacks exploit DC. With peer-to-peer there is no botnet and the attacker does not have to communicate with the client he is denying. Instead, the attacker acts as a "puppet master," instructing the client from the hub to share a large peer-to-peer file to disconnect from their peer-to-peer network and to connect to the victim's website instead.
Permanent denial-of-service attacks
Permanent denial-of-service (PDoS), also known as phlashing, is an attack that destroys the system so badly that it requires replacement or reinstallation of hardware. Unlike distributed denial-of-service attacks, PDoS attacks exploit security flaws that allow remote administration of the victim hardware management interface, such as routers, printers, or other network hardware. Attackers use this vulnerability to replace the firmware of the device with modified, damaged, or damaged firmware images - a process that if done legally is known as blinking. This is therefore a "brick" device, making it unusable for its original purpose until it can be repaired or replaced.
PDoS is a targeted pure hardware attack that can be much faster and requires less resources than using a botnet or root/vserver in a DDoS attack. Because of this feature, and possibly and most likely from security exploits in Network Enabled Embedded Devices (NEEDs), this technique has been the concern of many hacking communities.
PhlashDance is a tool created by Rich Smith (an employee of the Hewlett-Packard System Security Lab) used to detect and demonstrate PDoS vulnerabilities at the EUSecWest 2008 Applied Security Conference in London.
Attack reflected/spoofed
A distributed denial-of-service attack may involve sending false requests of some type to a large number of computers that will reply to requests. Using Internet Protocol address spoofing, the source address is set to that of the targeted victim, which means all replies will go (and overwhelm) the target. (This form of reflected attack is sometimes called "DRDOS".)
ICMP Echo Request attacks (Smurf attack) can be considered as one of the reflected attacks, because the host flooding (s) sends Echo Requests to the broadcast address of the mis-configured network, thus pulling the host to send Echo Reply packets to the victim. Some early DDoS programs apply a distributed form of this attack.
Amplification
The amplification attack is used to increase the bandwidth sent to the victim. This is usually done through a publicly accessible DNS server that is used to cause congestion on the target system using DNS response traffic. Many services can be utilized to act as reflectors, some more difficult to block than others. US-CERT has observed that different services imply on different amplification factors, as tabulated below:
DNS amplification attacks involve new mechanisms that increase amplification effects, using a list of DNS servers that are much larger than they were seen before. This process typically involves an attacker who sends the DNS name looking for a request to a public DNS server, spoofing the source IP address of the targeted victim. Attackers try to request as much information as possible, thus reinforcing DNS responses sent to targeted victims. Because the demand size is significantly smaller than the response, an attacker can easily increase the amount of traffic directed at the target. SNMP and NTP can also be exploited as reflectors in amplification attacks.
An example of a DDoS attack that is reinforced via Network Time Protocol (NTP) is through a command called a monlist, which sends the details of the last 600 hosts that request time from the NTP server back to the requester. Small requests to this time server can be sent using a fake source IP address from multiple victims, resulting in a response of 556.9 times the size of the request sent to the victim. This becomes reinforced when using botnets that all send requests with the same IP spoofed source, which will result in large amounts of data being sent back to the victim.
It is very difficult to defend against this type of attack because the response data comes from legitimate servers. This attack request is also sent via UDP, which does not require connection to the server. This means that the source IP is not verified when the request is received by the server. To bring awareness about this vulnerability, campaigns have started dedicated to finding amplification vectors that have caused people to fix their resolver or completely turn off the resolver. R-U-Dead-Yet.3F_.28RUDY.29 ">
R-U-Dead-Yet? (RUDY)
RUDY attacks target web applications with starved sessions available on web servers. Just like Slowloris, RUDY keeps the session stopped using a never-ending POST transmission and sends a header value of arbitrary content length.
Attack attack
The wolf attack is a denial-of-service attack on the Transmission Control Protocol. It uses short bursts of synchronized traffic to disrupt TCP connections on the same link, by exploiting weaknesses in the TCP timeout retransmission mechanism.
Slow Read attack
Slower read attacks send legitimate application layer requests, but read responses are very slow, so trying to drain the server connection pool. This is achieved by advertising very small numbers for TCP Receive Window size, and at the same time emptying TCP client buffer slowly, causing very low data flow rate.
Serangan Distributed Denial-of-Service terdedikasi bandwidth rendah
A sophisticated low bandwidth DDoS attack is a form of DoS that uses less traffic and improves its effectiveness by targeting weak points in the design of the victim system, ie the attacker sends traffic consisting of intricate requests to the system. Essentially, sophisticated DDoS attacks are lower in cost due to less traffic usage, smaller in size makes it more difficult to identify, and has the ability to injure systems protected by flow control mechanisms.
(S) SYN flood
SYN flood occurs when a host sends a flood of TCP/SYN packets, often with a counterfeited sender address. Each of these packets is handled like a connection request, causing the server to open a half-open connection, by sending back the TCP/SYN-ACK (Acknowledge) packet, and waiting for the packet in response from the sender's address (response to ACK Package). However, because the sender address is forged, the response never comes. This half-open connection saturates the number of available connections a server can make, keeping it from responding to legitimate requests until after the attack ends.
Teardrop Attack
Teardrop attacks involve sending out damaged IP fragments with overlapping, large payloads to the target machine. This can cause various operating system crashes due to bugs in the TCP/IP fragmentation assembly code. Windows 3.1x, Windows 95 and Windows NT operating systems, as well as versions of Linux before versions 2.0.32 and 2.1.63 are vulnerable to this attack.
(Although in September 2009, a vulnerability in Windows Vista was referred to as a "teardrop attack", this targeted SMB2 which is a layer higher than the TCP packet used teardrop).
One field in the IP header is the "offset fragment" field, indicating the start position, or offset, of the data contained in the fragmented packet relative to the data in the original packet. If the number of offsets and the size of a fragmented packet differs from the next fragmented packet, the packet will overlap. When this happens, the server vulnerable to teardrop attacks can not reassemble the packet - resulting in a service-rejection condition.
Disclaimer-service-phone (TDoS)
Voice over IP has made rough origins of a large number of cheap and easy automated voice calls while allowing the origin of calls to be misunderstood through caller ID spoofing.
According to the US Federal Bureau of Investigation, telephone denial of service (TDoS) has emerged as part of various fraudulent schemes:
- A scammer contacts a victim banker or broker, imitating the victim's identity to request a transfer of funds. The banker's attempts to contact the victim for the transfer verification failed because the victim's phone line was flooded with thousands of fake calls, so the victim could not be reached.
- Scammer customers contact with false claims to collect extraordinary salary loans for thousands of dollars. When a consumer object, the scammer responds by flooding the victim's employer with thousands of automatic calls. In some cases, caller IDs are displayed spoofed to impersonate police or law enforcement agencies.
- A fraudsters contact the consumer with a fake debt collection request and threatens to send the police; when the victim refused, the scammer flooded the local police number with a call whose caller ID was false to display the victim number. The police immediately arrived at the victim's residence trying to find the origin of the call.
Denial-of-service phones can exist even without Internet telephony. In the 2002 New Hampshire mobile phone wiretap scandal, telemarketers are used to flood political opponents with fake calls to phone phone hours on election day. Widespread publication numbers can also overwhelm with enough calls to make it unusable, as happened by chance in 1981 with some 1-area code-867-5309 customers inundated by hundreds of misdial calls daily in response to the 867- 5309/Jenny.
TDoS is different from other telephone harassment (such as prank calls and indecent phone calls) with the number of derived calls; by occupying a continuous line with automatic repeated calls, the victim is prevented from making or receiving routine and emergency phone calls.
Related exploits include SMS flooding attacks and fax or black fax transmission.
UPnP Attack
This attack uses a vulnerability that exists in the Universal Plug and Play protocol (UPnP) to get broad amound of the current defense methods and flood the network and the target server. This attack is based on DNS amplification techniques, but the attack mechanism is a UPnP router that forwards requests from one source to another without regard to UPnP behavior rules. Using the UPnP router returns data on unexpected UDP ports from fake IP addresses, making it more difficult to take simple actions to stop traffic flooding. According to Imperva researchers, the most effective way to stop this attack is for companies to lock UPnP routers.
Defense techniques
Defensive responses to denial-of-service attacks typically involve the use of a combination of attack detection, traffic classification and response tools, which aim to block traffic they identify as invalid and allow traffic they deem to be legitimate. The list of prevention and response tools is provided below:
Application front hardware
Front-end hardware applications are intelligent hardware that is placed in the network before the traffic reaches the server. It can be used on a network along with routers and switches. Front end hardware applications analyze data packets as they enter the system, and then identify them as priority, regular, or malicious. There are more than 25 bandwidth management vendors.
Application Level Key Enhancement Indicators
The approach to DDoS attacks against cloud-based applications can be based on application layer analysis, indicating whether incoming bulk traffic is legitimate and thus triggering elasticity decisions without the economic implications of DDoS attacks. These approaches primarily depend on the value path identified in the application and monitor the development of demand in this path, through a marker called Key Completion Indicators.
In essence, this technique is a statistical method for assessing incoming request behavior to detect whether something unusual or abnormal is occurring.
An analogy is for brick and mortar department stores where customers spend, on average, known percentages of their time on different activities such as picking up items and checking them, putting them back, filling the basket, waiting to pay, paying, and go. This high-level activity complies with the Key Resolution Indicator in the service or site, and once normal behavior is determined, abnormal behavior can be identified. If a bunch of customers arrive at the store and spend all their time picking up the goods and returning them, but never making a purchase, this can be marked as unusual behavior.
Department stores can try to adjust to periods of high activity by bringing employee backups with short notice. But if this is done on a regular basis, it is a mass to begin to appear but never buy anything, this could damage the store with additional employee costs. Soon the store will identify mass activity and reduce the number of employees, acknowledging that the mass is not profitable and should not be served. While this may complicate legitimate customers to be served during mass attendance, it saves the store from total destruction.
In the case of elastic cloud services where large and abnormal additional workloads can incur significant costs from cloud service providers, this technique can be used to reduce or even stop the expansion of server availability to protect against economic losses.
Blackholing and sinkholing
With blackhole routing, all traffic to the DNS being attacked or IP address is sent to "black hole" (no interface or no server). To be more efficient and avoid affecting network connectivity, it can be managed by ISPs.
A DNS sinkhole directs traffic to a valid IP address that analyzes traffic and rejects a bad packet. Sinkholing is inefficient for most of the heavy attacks.
IPS-based prevention
An intrusion prevention system (IPS) is effective if an attack has signatures associated with them. However, the tendency among the attacks was to have legitimate content but ill will. An intrusion prevention system that works on content recognition can not block behavior-based DoS attacks.
ASIC-based IPS can detect and block denial-of-service attacks because they have processing power and granularity to analyze attacks and act like circuit breakers in an automated way.
IPS-based tariffs (RBIPS) should analyze traffic in detail and continue to monitor traffic patterns and determine whether there are traffic anomalies. It should allow legitimate traffic flow while blocking DoS attack traffic.
DDS-based Defense
Focusing more on issues than IPS, the DoS defense system (DDS) can block DoS-based attacks on their connection and those with legitimate content but ill will. A DDS can also address both protocol attacks (such as teardrop and ping of death) and a rate-based attack (such as ICMP floods and SYN floods).
Firewall
In the case of a simple attack, a firewall can have a simple rule added to deny all incoming traffic from an attacker, based on the protocol, port or IP address of origin.
However, more complex attacks will be difficult to block with simple rules: for example, if there is an ongoing attack on port 80 (web service), it is not possible to stop all incoming traffic on this port because it will prevent the server from serving then legitimate traffic. In addition, the firewall may be too deep within the network hierarchy, with the router affected before traffic goes into the firewall.
Router
Similar to switches, the router has limiting level capability and ACL. They are also set manually. Most routers can be easily overwhelmed under DoS attacks. Cisco IOS has an optional feature that can reduce the impact of flooding.
Redirecting
Most switches have limiting rate and ACL capabilities. Some switches provide automatic and/or system-wide speed limiters, traffic generation, TCP splicing, in-packet inspection and Bogon filtering (Fake IP filtering) to detect and remake DoS attacks through automatic rate filtering and WAN Link removal and balancing.
This scheme will work during a DoS attack can be prevented by using it. For example, SYN flooding can be prevented using delayed binding or TCP connections. Content-based DoS can also be prevented using in-depth package inspection. Attacks originating from a dark address or going to a dark address can be prevented using bogon filtering. Automatic rate filtering can work as long as level setting is set correctly. Wan-link failover will work as long as both links have a DoS/DDoS prevention mechanism.
Upstream filter
All traffic is passed through a "cleaning center" or "rubbing center" through various methods such as proxies, tunnels, digital cross connections, or even direct circuits, which separate "bad" traffic (DDoS and other common internet attacks) and only send good traffic to the server. Providers require central connectivity to the Internet to manage such services unless they happen to be in the same facility as a "cleaning center" or "scrubbing center".
Examples of these service providers:
Unintentional denial-of-service
An unintentional denial-of-service can occur when a system ends up rejected, not because of a deliberate attack by an individual or group of individuals, but simply because of a sudden spike in popularity. This can happen when very popular websites post prominent links to second sites that are poorly prepared, for example, as part of the news. The result is that a significant proportion of regular users of major sites - potentially hundreds of thousands of people - click on that link within a few hours, having the same effect on the target website as a DDoS attack. VIPDoS is the same, but specifically when the link is posted by a celebrity.
When Michael Jackson died in 2009, sites like Google and Twitter slowed or even fell. Many site servers think that requests come from viruses or spyware that attempt to cause denial-of-service attacks, warning users that their queries look like "automatic requests from computer viruses or spyware applications".
News sites and link sites - sites whose primary function is to provide links to interesting content elsewhere on the Internet - will most likely cause this phenomenon. The canonical example is the Slashdot effect when receiving traffic from Slashdot. It is also known as "the embrace of Reddit of death" and "the Digg effect".
Routers have also been known to create unintentional DoS attacks, because both D-Link and Netgear routers have overloaded NTP servers by flooding NTP servers without respect to client type restrictions or geographical restrictions.
Similar denial-of-service similarities may also occur through other media, e.g. when the URL is mentioned on television. If the server is being indexed by Google or other search engines during peak activity periods, or does not have as much bandwidth available while being indexed, it can also experience the effects of DoS attacks.
Legal action has been committed in at least one case. In 2006, Universal Tube & amp; Rollform Equipment Corporation sued YouTube: a large number of potential youtube.com users accidentally typed in the company's tube URL, utube.com. As a result, the tube companies end up having to spend huge amounts of money to increase their bandwidth. Companies seem to take advantage of this situation, with utube.com now containing ads for advertising revenue.
In March 2014, after 370 Miss Malaysia lost, DigitalGlobe launched a crowdsourcing service where users can help locate lost jets in satellite imagery. The response made the company's server overwhelmed.
An unintentional rejection-service may also result from a pre-scheduled event created by the website itself, as is the case of the Census in Australia by 2016. This can be caused when the server provides multiple services at certain times. This is probably the university website that sets the value to be available where it will generate more incoming requests at that time than others.
Side effects of attack
Backscatter
In computer network security, backscatter is a side effect of a fake denial-of-service attack. In such an attack, the attacker spoofs (or forges) the source address in the IP packet sent to the victim. In general, the victim machine can not distinguish between fake packets and legitimate packets, so the victim responds to the usual fake packets. These response packs are known as backscatter.
If the attacker spoofs the source address randomly, the backscatter reply packets from the victim will be sent back to the random destination. This effect can be used by network telescopes as indirect evidence of such attacks.
The term "backscatter analysis" refers to observing the backscatter packets that arrive at a significant portion of the IP address space to determine the characteristics of DoS and victim attacks.
Legality
Many jurisdictions have laws where denial-of-service attacks are illegal.
- In the US, denial-of-service attacks can be regarded as a federal crime under the Computer Fraud and Abuse Act with a penalty that includes years of imprisonment. The Computer Crimes and Intellectual Property Department of the US Department of Justice handles cases (D) of DoS.
- In European countries, conducting a criminal denial-of-service attack can, at least, lead to arrest. United Kingdom is unusual because it specifically forbids denial-of-service attacks and imposes a maximum sentence of 10 years in prison with the Police and Justice Act 2006, which amends Section 3 of the Computer Abuse Act 1990.
On January 7, 2013, Anonymous posted a petition on the whitehouse.gov website requesting that the DDoS be recognized as a form of legal protest similar to the Occupy protest, the claim being that the similarity in the purpose of both is the same.
See also
References
Further reading
External links
- RFCÃ, 4732 Denial-of-Service Internet Considerations
- State of Akamai Internet Security Report - Statistics of Internet Security and Quarterly Trend
- W3C Worldwide Web Security FAQ
- cert.org The CERT Guide for DoS attacks. (historic document)
- ATLAS Summary Report - Real-time global report of DDoS attacks.
- Low Orbit Ion Cannon - Famous Network Stress Testing Tool
- High Orbit Ion Cannon - Simple HTTP Eraser
- LOIC SLOW Attempts to Bring SlowLoris and Slow Network Tools in LOIC
Source of the article : Wikipedia
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