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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Bruteforce vs Denial of Service

I had a problem presented today which I found quite interesting. You have an application with a management panel. You know some of the accounts as they are standard. You want two things: You want ...
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How to know what's the type of an attack and from whom is sent?

I'm currently running a game server on a dedicated Windows 7 machine and it is being attacked. How do I know what kind of attack it is and from whom is sent? When he attacks, the RDP freezes and the ...
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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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1answer
178 views

Are COMET installations immune to “Slow TCP Reading” DoS on Windows? (Such as SignalR or WebSync)

My understanding is that COMET implementations of WebSync and SignalR do not directly use IIS and are a few layers lower on the ISO model. After reading Qualys's blog regarding slow TCP reading, I ...
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1answer
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DoS anomaly-based detection: simplest approach beside simple threshold

As I learned, there is this technique in which the number of bytes/packets/frames of aggregated traffic is being checked to see if they deviate from a normal behavior. Then the time slot of that ...
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1answer
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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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2answers
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Good steps to survive from denial-of-service attack (DoS attack)

I need to follow several steps to safe our Web Project from DoS attack. Is there any guideline / steps? EDIT : We have our own server where we are running several e-Commerce websites. Our server's ...
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5answers
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What is a DoS Attack and how does it differ from a DDoS attack?

Can some one explain to me the concept of Dos Attacks for web applications ? Also what is the distinction between Dos and Distributed Dos ( ie DDos) attacks ? Wikipedia says : In computing, a ...
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2answers
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Can an attacker slow down my server without compromising it?

We have a Linux server with WHM/cPanel which has been running without problems for almost 3 years now. Yesterday, the server became unresponsive (it was definitely there though) for around an hour. ...
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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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Should you care about DoS attacks if your server is using bcrypt?

(I just asked this question on "cryptography SE" and was suggested to ask it here instead) EDIT I just realized my question is mostly a dupe of: Prevent denial of service attacks against slow hashing ...
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Global Blackout is a myth?

In order to shut the Internet down, anonymous claimed that putting-down the 13 root DNS servers of the Internet and therefore disabling the HTTP Internet, the most widely used function of the Web, ...
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Protecting against DOS attacks

Our current site is easily DOS'd. I can perform an AB test against it from Apache and it disappears for about 5-10 minutes. We have been having problems with others DOSing the site - to the point ...
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mitigating anonymous DOS (tor combined with pyloris)

I found this rather scary video in youtube, that takes DOS to a whole new level, by making it look like coming from multiple sources. As a counter measure to Rsnake (Robert Hansen) slowloris.py ...
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1answer
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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 ...
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4answers
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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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3answers
436 views

Is it possible to “close” a port by dos'ing it?

If I see port 25 is open, but I dont have access to the program running the smtp server, could It be flooded with enough information to make it unusable (but not affect any other services)?
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Looking for information about CVE-2006-6876 vulnerability

In order to study vulnerabilities of a SIP server and the impacts of DOS attacks on the QoS of VoIP service, I have found this vulnerability which can be exploited to cause DoS on SIP server. But I ...
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1answer
218 views

Differentiate normal flow and broadcast attacks

How do you identify whether a broadcast traffic is normal or is considered an attack such as a DoS attack?, There is some information that the plot or the source that allows me to differentiate ...
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Mass account lockout prevention using CSRF tokens

I'm currently working on reducing the risk of mass account lockout on a site that (unfortunately) issues sequential, numeric user IDs. Changing the structure of the userID is not an option at this ...
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1answer
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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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1answer
118 views

DoS and Serialization

I got the following message from Fortify static code analyser. Incorrect serialization and de-serialization can lead to unpredictable behavior and cause denial of service attacks. Can anyone ...
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Protection against account lockout DoS

Any ideas on how to protect against the following scenario? Company x uses active directory for authentication of it's employees. The company has multiple authentication points that are semi-public ...
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Can I trust the source IP of an HTTP request?

As far as I've understood, if you try to issue a HTTP request with a spoofed IP address, then the TCP handshake fails, so it's not possible to complete the HTTP request, because the SYN/ACK from the ...
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1answer
765 views

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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4answers
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I think I accidentally DoS'd a website. What should I do?

I was browsing a website, and stumbled across a sample scheme for password-protecting web pages. The owner of the website specifically had a page that invited people to attempt to hack it. I wanted ...
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How to conduct DDoS attack practically? [duplicate]

Possible Duplicate: How to simulate DDoS attacks from the Internet? I want to conduct a DDoS attack. Can anyone please tell how can i conduct it? What are the latest DDos attacks? What are ...
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How does a DOS attack work when attacking a single server with a single client?

How is it possible to make a DOS attack from a single computer? Let us assume two computers, one acting as server and the other as client. Both has 100/100 mbit bandwitdh. How can then the client ...
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How do I protect my Windows computer against the IPV6 flood attack shown in this video

In the DefCon video "Three Generations of DoS Attacks (with Audience Participation, as Victims)", the speaker demonstrates how it is possible to crash a variety of devices by flooding them with IPV6 ...
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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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4answers
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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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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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2answers
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How to defend against SSL-Exhaustion attacks?

The problem of SSL-Exhaustion attacks is well known for years, but nobody really cared until THC released their exploit-tool recently. THC talks about counter measurements in their release: No real ...
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Combat Apache Killer

Three days ago, KingCope released a simple Perl script to DoS Apache, aptly named Apache Killer. This script launches about 50 threads to request Partial Content from the server with optional GZIP ...
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Why do sites implement locking after 3 failed password attempts?

I know the reasoning behind not letting infinite password attempts -- brute force attempts is not a meatspace weakness, but a problem with computer security -- but where did they get the number 3 ...
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What lessons about Denial of Service can we learn from Egypt's “experiment”?

Internet service was widely disrupted in Egypt starting Jan 27th at about 22:15 UTC, in the space of about 20 minutes: How Egypt Killed the Internet. Service was largely restored 5 1/2 days later on ...