Questions tagged [denial-of-service]

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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Snort rule for syn flood attacks - Limiting number of alerts

So I have a snort rule that detects syn flood attacks that looks like this: alert tcp any any -> $HOME_NET 80 (msg:”SYN Flood - SSH"; flags:S; flow: stateless; detection_filter: track by_dst, ...
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How can one mitigate both account-level DOS attacks and online brute force attacks at the same time?

I was recently reading this question, where the accepted answer claims that it is easy for attackers to bypass rate limiting that is based on IP, which makes any sort of IP rate limiting to prevent a ...
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How to DOS a personal IP as beginner? [closed]

I am curious on learning the skill of a DOS attack on a personal IP. I was doing it to a close friend of mine (he agreed to do so) by pinging his IP using the command prompt. But the problem is that ...
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Entrypoint on webapp allows semi-arbitrary data to be written. Can it be considered as DoS?

My team and I have written a web app, and we had a bug report regarding a DoS vulnerability. This vulnerability, requires a basic account to be created and allows this user to inject semi-arbitrary ...
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How to understand the SYN-cookie technology's SYN to Server? [closed]

The snapshot is about syn-cookie technology: How to understand the Server' and Client' in this snapshot? Whether the Client':SYN is the second time initial SYN of Client? or is Client's first time ...
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4answers
130 views

How to identify IP from a UDP-based DoS

I'm running a Counterstrike server on UDP port 27015. I'm using Amazon AWS to host the game server. I have added only my friends' IPs (about 50 of them) into a security group so the rest of the ...
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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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628 views

How do you shun an IP automatically based on the number of current connections?

If I have a single IP that's trying a Denial of Service attack, how can I automatically have it banned/shunned? I go in and manually put it in a group of banned IP addresses, but I'd like for it to ...
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Is the half_md4 dirent hashing algorithm a security problem in ext* filesystems?

half_md4 does not look a very strong hash for me, although googling for it does not reveal too much. I suspect, the directory entries could be organized by a half_md4 hashed hash table. If it is so, ...
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Apache/Linux server, DoS attack from own IP

I have an unusual problem I've been trying to diagnose for a while: It's about a Debian server running a custom compile of apache 2.2 with PHP, Red5, MySQL 5.5 (standard binary), sendmail (distro ...
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Calculate pps for DDoS evaluation

I am working on a task where I have to evaluate how much throughput one can generate in packets per second. I know I can send them as fast as possible with hping3 [...] --flood, but is there a way to ...
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How fill up a gig interface bandwidth with hping3?

I've been trying to test our software against DOS attacks. So, I used 'HPing3' but it just fills up 10-11M of my interface's bandwidth! I ran the tool 40 times, I mean 40 hping3 processes, ...
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Network overload due to attack [duplicate]

My hosting provider (ovh) recently blocked my VPS due to some attack on the server. When I restored it to the normal mode, I can see indeed something is happening: the access to server is limited, ...
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4answers
436 views

Password hashing that is resistant to ASIC-assisted cracking without risking DoS of server

Previously, authentication systems stored passwords in cleartext. This made it trivial for an attacker to log in to an account if he had access to a leaked password file. Later, passwords were hashed ...
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1answer
394 views

Are these log messages in my nginx server evidence of an attempted attack?

My AWS Elastic Beanstalk server is often reporting Environment health has transitioned from Ok to Severe. 100.0 % of the requests are erroring with HTTP 4xx. This happens almost daily for a few ...
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72 views

Does a DDOS attack on an application using CDN have to first bring down all the involved CDN servers to affect the application's availability?

CDN are said to absorb and mitigate the Denial of Service and DDOS attacks. Consider an application that uses a CDN provider to deliver its content. So if an attacker tries to bring down such an ...
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9answers
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How does CAPTCHA mitigate DDoS attacks?

This seems like an easy question, but I've failed to find an answer. One of the uses of CAPTCHA is to cope mitigate Denial of Service attacks. Suppose an adversary performs excessive login attempts, ...
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99 views

lan-side denial of service affecting target's CPU performance

Why does a LAN-side UDP flood take up the target's CPU resources and make it sluggish? i.e: the mouse doesn't respond properly, opening an application is slow... Note: The computers are both ...
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Preventing artificial latency or “Lag Hacking” in multiplayer games

There is an attack that some people have dubbed "lag hacking", and its gaining popularity in multiplayer games. There are at-least two ways of creating artificial latency. One method of introducing ...
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103 views

Types of firewalls to implement to reduce DoS attacks in POS systems

Would you need an internal, external and a host-resident firewall for each POS client?
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48 views

Can an ethernet device plugged into a switch block all the other ethernet devices?

And if so, what protections are available against this kind of thing?
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Can a process be DoSed by interfering with its compare-exchange loops?

Consider a file accessed by multiple processes; the processes map the file to memory and then use lock-free operations to synchronize (for example, use atomic-add to allocate an offset in the file to ...
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Preventing DoS Attacks on NFC

There are some attack scenarios on NFC. These include e.g. Data modification, data insertion, relay attacks and DoS attacks. Just to name a few. While some of these attack scenarios are more likely ...
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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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Is Slowloris traceable? [closed]

When someone launches a slowloris attack on a website, could that attack be traced via IP? Could someone feasibly locate the IP of the person that launches said attack?
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Preventing DoS and flooding attacks on wireless MANET network

How can I prevent DoS/flooding attacks on a wireless MANET network?
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What is a DoS Attack and how does it differ from a DDoS attack?

Can someone explain to me the concept of DoS attacks for web applications? Also, what is the distinction between DoS and Distributed DoS (i.e. DDoS) attacks? Wikipedia says: In computing, a denial-...
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What type of vulnerabilty is this?

I'm testing a website: https://this-site.com/path/to/dirs but what i've found is if I do the following below the site will load 4 pages in a infinite loop https://this-site.com/path/to/dirs/.../. ...
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1answer
483 views

Is there a multi-layered DoS protection which can be tightly integrated with cloud hosting services?

I know that one can deny services (DoS) in any of the 7 layers of the OSI model and that in principle, a denial can be done by a single entity (human or machine) or from 2 or more such entities ("...
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765 views

How to test CVE-2004-0789 Multiple Vendor DNS Response Flooding Denial Of Service?

I use Nessus to check vulnerabilities on my webserver. It is a Windows Server. Nessus reports that this particular server has a CVE-2004-0789 vulnerability. Here is the description from Nessus: The ...
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245 views

Client reconnects during deauthentication attack

During my first deauthentication attack the client I targeted was disconnected from the wireless network, however I was able to reconnect the client to the network even though aireplay-ng was still ...
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UDP amplification: length(response_packet) < length(request_packet)

I was researching the GitHub DDoS attack of 2018, in which memcached UDP amplification was used. I noticed that a GitHub blog post referenced a CloudFlare post which described memcached-based UDP ...
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Is it safe to pass user input through rails gsub?

Are there risks associated with using gsub on user input? Can it be used for regular expression DoS?
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How dangerous is it to allow arbitrary webhook urls to post to?

I am building a Ruby on Rails API that posts to webhooks that the API user can create, whenever a resource that he manages is created, updated or destroyed, using the HTTParty gem. This got me ...
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Regex DoS: Is OWASP's characterization of “evil regexes” complete?

OWASP defines "evil regex" (here) as follows: Evil Regexes A Regex is called "evil" if it can stuck on crafted input. Evil Regex pattern contains: Grouping with repetition ...
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I'm getting DoS'ed [closed]

For a few days my internet started being very slow. I checked my router logs and guess what! In the log where it is a record of DoS attacks it showed something like |Description |...
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106 views

infinity redirection as Dos Attack

I was wondering that infinite redirection could be used as a dos attack in my case, I have this test.php <?php $url = $_GET['url']; header('Location: '.$newURL); ?> ...
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1answer
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Is Mailbait still a threat?

Is Mailbait (or similar services) still a threat, was it ever a threat, and if so how can it be mitigated? Mailbait is that service that promises to fill up your email inbox by sending you a huge ...
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1answer
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Can/do botnets brute force “high value” users of services like Gmail?

On an intranet a login is generally disabled after a very small number of failed logins. But a public email service like Gmail can't do the same, otherwise pranksters would just be continuously ...
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How can I block an IP, if I'm getting many http requests in a second?

If some one tried force burst attack on my website, how can I block them? Ideally, I want to block an IP if I have many http/Apache requests in a second.
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Failed logins on a windows server - performance impact?

I have recently started analysing our logs and noticed 600-700 failed login attempts per day against a windows 2016 server hosting some shared files. I know what the cause is (another misconfigured ...
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Validation issue in name field causes the page to hang

I am using a webpage that doesn't have validation for name field. If I give any special characters, the page just becomes unresponsive. Though the captcha times out after some time, the request still ...
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3answers
301 views

What websites would I be allowed to DoS?

I recently wrote an automated DoS script and was wondering 2 things: Would I be allowed to use it on hackthissite.org? Would I be able to make a Wix site and use it on that?
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Is Windows 10 Vulnerable to IPv6 Router Advertisement Flooding?

In a DEFCON 19 video Sam Bowne says that windows 7 machines CPU goes to 100% if you send a bunch of IPv6 Router Advertisement requests on a network. What would happen to a Windows 10 machine? Would it ...
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what kind of attack is this

Im developing a website on test server and so when debugging some stuff I had to look in access log, this is a small chunk of what I saw: 37.99.49.203 - - [13/May/2019:17:51:34 +0200] "H\x1E\xF3qxZ\...
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2answers
468 views

Billion Laughs Attack (XXE) - how does it work

Hi all Im trying to understand how the billion laughs attack works(https://en.wikipedia.org/wiki/Billion_laughs_attack) So far I get its obviously sending this payload: <?xml version="1.0"?> &...
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1answer
636 views

How do you prevent/guard against a wireless disassociation attack [duplicate]

Going over the security+ lectures by professor Messer here, he explains and demonstrates a wireless disassociation attack very well. But no where in the video does he explain how this type of attack ...
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2answers
293 views

Why were hyperlink auditing pings used for DDoS attacks and not any other requests?

A few days ago this new story has been published: Researchers have found that the HTML feature called hyperlink auditing, or pings, is being used to perform DDoS attacks against various sites. This ...
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148 views

WiFi Channel 6 unusable, but no other AP on Channel 6

There is a single MAC address broadcasting a vast amount of QoS packets on channels between 3 and 9. Is this a DoS attack? The access point that MAC address is associated with says its on channel 1. ...
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105 views

Question about hping3, TCP and ngrok

I have set up a experimental setup which consists of: Windows PC with ethernet cable; Arduino shield (connected to Windows machine with USB) with LTE connectivity sending data using TCP/IP to ngrok; ...

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