Denial of Service is a family of attacks that attempt to force a target to use up resources (CPU time, memory, bandwidth etc) through flood a target with useless packets, connections or tasks

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Parabolic Denial Of Service — Would it work?

Would this DoS attack be effective: Attacker determines target (10.0.0.1) Attacker sends ack packets to a buch of web servers with a src addr of 10.0.0.1 Servers reply to 10.0.0.1 with syn packets ...
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How can one defend against DoS attacks at the physical layer?

Of course, there's always the odd issue of old microwaves and wireless telephone handsets interfering with Wi-Fi performance. And, in many areas, there's a fair chance that you're going to have to ...
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What are HTTP GET/POST flood attacks?

I want to know what the main differences are between HTTP GET and POST flood attacks and mitigation strategies for both. I searched a lot but I really can't find some good articles nor examples about ...
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Is this type of ARP poisoning attack possible?

I am wondering if it is possible to paralyze a network by sending out a bunch of fake ARP response packets. Some basis: I recently read a moderately detailed description of how ARP and ARP poisoning ...
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First steps in preventing DOS attacks

My server is currently being attacked from another server. This is my log: root@my-server:/var/log# tail -f auth.log Feb 19 11:53:08 my-server sshd[3745]: Disconnecting: Too many authentication ...
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How can I detect/withstand DNS amplification attack?

I am a developer, and I am trying to get an insight into what could I do to enable my application to withstand a DNS amplification kind of attacks. Would such prevention methods help against DOS type ...
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UDP flood from my machine, or false positive?

The company that hosts my dedicated server has alerted me to what they think is malicious traffic coming from my machine. They supplied me with graphs showing a large amount of UDP traffic coming from ...
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Resource consumption attacks against algorithms

I am studying algorithm construction and weaknesses to resource consumption. One vulnerability that really caught my eye was the Apache Range Header DoS Vulnerability. The following quote was taken ...
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Lessen impact of DoS attack on cpu-expensive login?

This is a follow-up to my previous question: Prevent DOS against RSA authentication. This question is also discusses a similar problem: Prevent denial of service attacks against slow hashing ...
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How can the Android GraphicBuffer::unflatten() vulnerability (CVE-2015-1474) be exploited remotely?

I've been reading up-on DoS (denial-of-service) attacks within android and although I understand attacks like the below, which make use of regular programming functions etc. (Android Web Browser) ...
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Is there any protection against malicious devices on a CAN bus?

CAN (controller area network) is a bus used in all modern cars. You can read a lot of the cars information over this bus and I think (but I'm not too sure about this) that some critical control ...
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How can I defend against malicious GET requests?

My server is getting hit with a variety if requests like the following: Started GET "/key/values" ActionController::RoutingError (No route matches [GET] "/key/values") Started GET "/loaded" ...
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How are server overload and DoS/DDos different?

I know that server overloads are caused due to excessive number of genuine requests and DoS due to malicious request. But, my question is, if you have designed a system for Overload mitigation, does ...
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How could a SYN flood affect a home router

I was curious how a DoS attack would affect a home router. In particular, I'm interested in how a SYN flood would affect a home router. The reason I'm interested is due to a Cisco document I read. ...
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Is this a symptom of an attack (DoS/DDoS)?

I work for an e-commerce website in my country and this is the second time we suffer an attack. At least, looks like one. We have a search functionality in our website and the supposed attacker is ...
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DoS by consuming all hosting trafic

Given a small website hosted on a small data plan, is it possible for someone to keep doing requesting for my website URL or just an image hosted on my website that will consume all my permitted ...
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Are latency based Proof-of-Work systems capable of preventing DDoS attacks on popular hidden tor services (.onion websites)?

I was reading an interesting article found here: http://www.cl.cam.ac.uk/techreports/UCAM-CL-TR-703.pdf It's titled "Lazy Susan: dumb waiting as proof of work". It suggested the following in section ...
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How does a Distributed Denial Of Service Attack work

Let's assume that a hacker has already infected an X number of PCs , each one of them is online. How will he actually perform this attack? Just send ping requests or use his very precious tool to do ...
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Measuring SNR to detect jammers in Wi-Fi networks

I'm trying to figure out a way to detect a Wi-Fi 2.4 GHz signal Jammer. I am not looking into locating the location of the jammer but rather detect the jamming signal. How do i do so using only ...
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What are the mitigating factors for CVE-2015-5364?

CVE-2015-5364 describes a UDP based DoS vulnerability in the Linux kernel that can be used to deny processing cycles to the host operating system and its applications. ...
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What's happening on my wifi? NTP and ACK STORM attacks.

I'm wondering if these attacks are something to worry about, or just my router being a router. [DoS attack: ACK Scan] attack packets in last 20 sec from ip [60.221.254.230], Friday, May 06,2016 ...
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How to mitigate UDP flood attacks?

My friend linked me some website where you pay $5.00 / m and get access to a plethora of 'dos stresser' tools that offer udp flooding, and other malicious flooders. It's a web-based system and you ...
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If I send 4mbps of data to a friend with 4mbps connection, will I DoS him?

Suppose my friend has a connection of 4mbps. If I just send him 4mpbs of random data with my server, wouldn't it block his connection? Even if the router has firewalls and closed ports, isn't enough ...
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Can this be a DoS Attack?

When I'm checking my log, I found like 15k events of " PAM service(sshd) ignoring max retries; 6 > 3 " I know this might be normal, and considered as Brute-Force attack, but can it be classified as ...
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Is it safe to ignore DoS attacks on my router?

There are several entries in my router's log file showing recent DoS attempts on some of its ports. They look like this: [DoS Attack: ACK Scan] from source: 213.61.245.234, port 80, Friday, November ...
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How is DDoS different from DRDoS?

I understand DDoS is a DoS assault from multiple sources, where a coordinated stream of requests is launched against a target. How is DRDoS different?
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Using SYN cookies to perform a DOS attack

In my software security class, we had this question: You are the system administrator for a provider that owns a large network (e.g., at least 64,000 IP addresses). Show how you can use SYN ...
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Can a Cisco ASA 5505 block this DDoS attack?

Since more than a week ago, my dedicated server (located at ovh.com) has been under TCP SYN (I think) attack. OVH don't care about it but this attack is killing my server with a high CPU load ...
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What is this strange GET request (GET /A0A32579-2767) DoSed my apache?

I have apache behind nginx on my webserver. Today my apache stops answering to requests. Investigations shows this situation: Number of apache processes grows more that 500 but MaxChildren=256 in ...
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How to defend against a Spoofed-IP Blacklist DOS attack?

So I've implemented an IP Blacklist for the /login endpoint on my server. If any IP fails to login more than x number of attempts in x number of minutes the requesting IP is blacklisted for x number ...
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HTTP attack taking down PHP-FPM [closed]

Someone started attacking my site a few minutes ago and its caused PHP-FPM to max out all cores (4) on my vps and NGINX is now serving 502 to all users. I'm seeing a bunch of these requests with tons ...
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Prevent DOS against RSA authentication

In my current setup, the clients are bundled with the server's public key. The client encrypts a nonce and sends it to the server which uses its own nonce and the nonce received from the client to set ...
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Security monitoring in the cloud?

I am working for a company which works with PHI, HIPAA, PCI and other highest sensitivity data. Their current security architecture uses hardware network monitoring tools to monitor the network ...
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Reverse-proxy not a solution to DDOS attacks when hosted on PaaS?

We run our apps on Heroku and use Cloudflare as a CDN and to protect against DOS attacks. However, we recently experienced (a relatively minor) attack that managed to easily bypass Cloudflare by ...
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Deny attacker access to my router

I was experiencing very low connectivity on my wireless, so I checked the router logs. Here's what I saw: Jul 09 11:07:24 Per-source ACK Flood Attack Detect (ip=74.125.130.129) Packet Dropped Jul 09 ...
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DOS safe alternative to delay response to an attacker with sleep()?

tl;dr sleep() costs my servers resources. Using it to delay response to the attacker might cost him/her time, but allows for DOS. Is it possible to keep him/her waiting without costs of mine? Long ...
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HPKP-based persistent denial-of-service attack on web sites

HTTP Public Key Pinning (HPKP) is a standard that allows a HTTPS website to specify which certificates it trusts, and instruct the browser not to allow any connection to that site that's secured by ...
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What to do if I accidentally DoS a site? [closed]

A few weeks ago I was non-maliciously using a website with server-side calculations when curiosity got the better of me and I decided to mess with some GET request values. I expected the site to give ...
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How web application firewalls protect application from DDoS attacks?

How to protect a web application from DDoS by the implementation of Web Application firewalls? How effective is this method?
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How to send GET/POST requests without header and agent information

I want to test our DOS prevention system against http requests that are not have header and agent information. Is there any tool I can do that. I tried siege with this command siege -c 3 -b -H ...
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What to do when GSM/Wifi is jammed and ethernet cables are cut?

So.. There are household alarm systems (to defend against burglars) which send SMS/e-mail alerts if an intruder has been detected or an alert is trigged. However, Mobile networks can be jammed, and ...
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Are there any risks to matching user-supplied regex against user-supplied inputs?

I have an IRC bot written in python3 that parses user requests for search and replace. Is there any risk of DoS or other attack by doing this?
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SYN flooding attack causing high CPU on hardware firewall

I have a ZyWall USG 200 firewall. A few days ago there was a SYN flooding attack on it causing 100% CPU load. After investigating it turns out this was attack from a single IP address and while the ...
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How can I constrain or limit 3rd party Javascript (*.js) files that can DOS my site?

Many website owners integrate Google analytics, various Facebook or Twitter social media javascript plug ins into their web pages. The problem is that this trust seems to be "all or nothing", meaning ...
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Could somebody explain connect loop DoS?

I'm trying to understand this vulnerability. How can I reproduce this?
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DoS attacks and bitcoin

I was wondering what the repercussions were if a Bitcoin exchange or website that holds bitcoins were to succumb to a DoS attack. In my understanding, all a denial-of-service attack does is deny ...
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Why should an IKE responder change the cookie secret 'frequently'?

IKEv2 has the concept of a COOKIE mode, to attempt to prevent state exhaustion from floods of initiation requests from non-existent IP addresses: Two expected attacks against IKE are state and CPU ...
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UDP Flood Attack false positive

Symantec keeps blocking traffic from the IP of my Comcast SMC Network gateway. It blocks traffic because it is detecting a UDP Flood Attack. According to the log the CPU usage is spiking to 100% when ...
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RSnake's Slow Loris tool

I was looking at RSnakes implementation of his Slow Loris done on perl which can be seen here. I set up a little server to listen to his packets, and at first found this GET / HTTP/1.1\r\nHost: ...
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SSL Based Denial of Services due to Message Digest

On a very high level, its known that SSL/TLS uses message digests to verify the integrity of the messages sent. However, the question I have in mind is : How does SSL ensure a DoS does not happen ...