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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How actually Denial of Service (DoS) attack is performed? [on hold]

I studied that in a DoS attack, attacker make a network/machine inaccessible to the intended users. Different servers have different specification like a small local server would capable of ...
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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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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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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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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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1answer
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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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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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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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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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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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137 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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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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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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586 views

Detect / Prove and Prevent Wifi Deauth attack

I'm suspecting that my neighbor is running multiple Wifi deauth flood attacks against my Wifi. I'm using WPA2 and I don't think he can really crack my password, but my devices keep having wifi ...
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923 views

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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Can jumping to a new SSID be a solution for flood attacks?

If an attacker can access inside my network in any way and make a UDP or ICMP flood attack on any point of the network (server, client or router), can I prevent this attack transiently with jumping on ...
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Is this regular expression vulnerable to DoS?

FindBugs flagged the following email address validation regex as vulnerable to DoS: ^[\w!#$%&'*+/=?`{|}~^-]+(?:\.[\w!#$%&'*+/=?`{|}~^-]+)*@(?:[a-zA-Z0-9-]+\.)+[a-zA-Z]{2,6}$ Here's an easier ...
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Does limiting the length of a password help prevent DoS attacks? [duplicate]

I was told that you can DoS a server with unlimited password length because of the time that it would take to hash it. But isn't the password hashed on the client's side before leaving the user's ...
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What is the difference between an SYN-Flood attack and an SYN-ACK-Flood attack?

What is the difference between an SYN-Flood attack and an SYN-ACK-Flood (SYN Reflection) attack?
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Does it make sense to consider a triggerable server software crash a DOS attack?

I've found a little vulnerability in a web application running on Node.js server. It works by sending some crafted payload to the application server, which makes the application server code to throw ...
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Risk and probability from CVE

How can I find risk and probability from CVE (https://cve.mitre.org/)? I read an article and it says (pg 14), The cost is derived from the attack tree, and risk and probability are based on CVE ...
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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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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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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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383 views

Nginx: mod-security rule for http slow DoS attack

The only related rule in mod-security for slow DoS is modsecurity_crs_11_slow_dos_protection, and it's for Apache only. Is there a rule for Nginx?
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Addressing availability element of CIA triad using technical controls

When looking at the availability element of the CIA triad, most definitions mention that availability is addressed through ensuring system up-time by using controls such as disaster recovery, business ...
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458 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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Account lockout to protect from brute force: doesn't it open up vulnerabilities to DOS attacks? [duplicate]

AFAIK the recommended practice to mitigate brute force attacks is to lock an account down for, say, 15 min (perhaps escalating lockout time if the attack continues afterwards?) after, say, 5 failed ...
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How to identify a Ping of Death attack by analyzing its packet in Wireshark? [closed]

I've tried researching it for a long while, but came out dry.
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190 views

Are NTP servers without monlist still dangerous?

I've been studying DOS flood attacks, namely NTP and DNS floods. I know that monlist is the primary factor in launching these sorts of attacks, but I have one question. The problem is are these ...
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Threshold for DDOS Attack

I am trying to understand and simulate SYN Flood DDOS attacks. I am using snort to give me alerts. While I have control over the rate for my testing, I am interested in knowing what a good estimate of ...
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How is satellite uplink secured from DOS attack?

How satellite communication is secured from Denial of Service attack on up-link frequency as anyone can create interference?
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5k views

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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Most reduced types of DoS attacks

As I understand it, there are generally only two common types of Denial of Service attacks in regards to the OSI model: Network-Layer-DoS (NLDoS) on layers 3, 2 or 1. Application-Layer-DoS (ALDoS) on ...
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Is a DoS attack possible on a single home connection when the ISP uses NAT?

Today almost all ISPs use a NAT system to assign more people the same IP (at least where I am), probably because the IPv4 addresses are ending and they want to save money. Is it possible to make a DoS ...
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Why is DDOS is one of the most common Cyber-Attack? [closed]

Based on some articles and some research DDOS is one of the most common cyber-attack. There are tonnes of articles out there about the DDOS subject, including describing, mitigating, the question "...
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Difference between DNS flood attack and DNS amplifier attack [duplicate]

I am trying to understand DNS flood and DNS amplifier attack. I have read the definition and am still confused, could you give me an example of each attack or tell me the differences between them? It ...
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Is it safe to let a user type a regex as a search input?

I was in a mall a few days ago and I searched for a shop on an indication panel. Out of curiosity, I tried a search with (.+) and was a bit surprised to get the list of all the shops in the mall. I'...
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How perform Ping Flood, Ping Of Death, and Teardrop on local network?

Is it possible nowadays to perform a Ping Flood, Ping Of Death, and Teardrop on local network? According to this article, these three attack are useless and out of date. I'd like to test this on my ...
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How to detect a DoS attack if today all use network address translation?

If a basic DoS attack can be handled by limiting the number of connections that occur in a interval of time with one IP and some enterprises and institutions use network address translation with many ...
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571 views

How to avoid XML vulnerabilities in Python?

I am writing a suite of Python 3 applications (including first a command line utility, second an HTTP(S) proxy) which deal with XML. Today I've discovered that there are several vulnerabilities ...
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452 views

A way to prevent non distributed, network-level DoS attacks?

I have a DigitalOcean Ubuntu 16.04 machine with Bash as main shell, Nginx, PHP-FPM, and MySQL as server environment, Certbot for TLS and WordPress for web applications. I protect from MITMs with TLS. ...
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SYN-flood to the localhost Apache server

I've set up the apache server on localhost (127.0.0.1). I've downloaded PackETH to perform a DoS attack. So PackETH wants MAC-HEADER of the destination and source. And I don't know, where to find ...
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What do DoS/ DDoS TCP SYN Floods and Layer 7/HTTP floods look like on a firewall log?

I am looking for some examples of log files for DoS or DDoS attacks that show a SYN Flood or a HTTP/Layer 7 Flood. I have had a google, but can't seem to find anything. Would the incoming packet ...
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Protecting WordPress from a single machine DoS (either in network/web level)?

I use a DigitalOcean Ubuntu 16.04 machine with Bash, LEMP and WordPress. I already did the best I can to protect the system and WordPress from BFAs and Backdoors, and to protect WordPress from DB ...
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Is DDoS a specific type of ALDoS

In a very broad terminology: I understand Application Layer Denial of Service (ALDoS) to be a 1 machine on 1 machine attack. I understand Distributed Denial of Service DDoS (DDoS) to be a 2 or more ...