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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1answer
840 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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2answers
54 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
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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1answer
2k views

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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3answers
33k views

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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1answer
150 views

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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1answer
48 views

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
41 views

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
257 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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1answer
138 views

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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1answer
62 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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169 views

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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1answer
75 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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2answers
184 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
180 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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1answer
34 views

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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2answers
264 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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0answers
136 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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1answer
58 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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1answer
422 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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0answers
63 views

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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2answers
206 views

role of ISP in defeating Dos DDoS

What is the role or responsibility of my ISP to protect my network that is connected through their network to the Internet against DDoS / DoS ?
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1answer
111 views

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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4answers
12k views

Best way to report a foreigner attacker's ip to authorities?

I have been under attack last week and I was able to trace down the attacker and get his IP address. The attacker was located in Germany but I live out of Europe? From your experience what is the ...
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4answers
748 views

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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2answers
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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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7answers
12k views

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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2answers
84 views

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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3answers
450 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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2answers
8k views

Understanding Layer 7 DoS

I recently read this article about how a lone hacker (The Jester) conducts, amongst various other things, his DoS attacks over layer 7 instead of layer 4. It also mentions at one point he was able to ...
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4answers
11k views

Why does a (D)DoS attack slow down the CPU and crash a server?

So I get the basic idea of (D)DoS used for flooding, but I don't quite understand how this causes servers to crash or get them to slow down due to CPU overuse. As far as I know, the thing that is ...
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3answers
267 views

How to protect my network against local flood attacks?

I installed VM centOS 6.8 then I installed hping3 tools. With this tool, I can take down any PC connection on the network as well as increase CPU and RAM usage with the following command hping3 --...
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1answer
456 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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1answer
349 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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1answer
63 views

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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2answers
302 views

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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1answer
598 views

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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1answer
181 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 ...
147
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7answers
31k views

Can someone take down Wi-Fi signal?

Is it possible that someone made an attack (DoS or something else) to my Wi-Fi router (without knowing of the password) and make my router's signal unavailable? 1) How it can be done? 2) What are ...
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3answers
2k views

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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0answers
77 views

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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1answer
7k views

Secure Client-Initiated Renegotiation - DoS DANGER

I tested my server against cryptographic attacks and I have a few major and minor issues. However I would like to know how can I mitigate and protect against such vulnerability warning: Secure Client-...
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4answers
640 views

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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2answers
13k views

How can ISPs handle DDoS attacks?

How can an ISP with low bandwidth like 50 Gbps handle a DDoS attack with more than this? I know there is a solution called "Black Hole". Is this enough to mitigate DDoS attacks or are there any other ...
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5answers
9k views

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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3answers
79k views

nf_conntrack: table full, dropping packet

I see a lot of these messages in /var/log/messages of my Linux server kernel: nf_conntrack: table full, dropping packet. kernel: __ratelimit: 15812 callbacks suppresse while my server is under DoS ...
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2answers
245 views

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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3answers
370 views

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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1answer
708 views

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 ...