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285 votes
Accepted

Can someone take down Wi-Fi signal?

There's a lot of ways you can attack a WiFi without knowing any passwords: Physical layer attacks: Simply jam the frequency spectrum with your own signal. That signal might just be noise, but it ...
Marcus Müller's user avatar
136 votes

Does it make sense to consider a triggerable server software crash a DOS attack?

Yes. Any attack which has as a goal to deny the normal usage of a service by legitimate users is by definition a DoS (Denial of Service).
DarkMatter's user avatar
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98 votes
Accepted

How can ISPs handle DDoS attacks?

There are a number of strategies, each having their own costs and benefits. Here are a few (there are more, and variations): blackholing By blackholing traffic, you discard all traffic towards the ...
Teun Vink's user avatar
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85 votes
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Is it safe to let a user type a regex as a search input?

I would compare accepting user supplied regular expressions to parsing most sorts of structured user input, such as date strings or markdown, in terms of risk of code execution. Regular expressions ...
Ryan Jenkins's user avatar
84 votes
Accepted

Can a DDoS attack yield any information?

A DDoS will certainly give an attacker information about response times, load capability and routing. It may also give information about how incidents are handled internally and externally, as well ...
Rory Alsop's user avatar
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59 votes

Does it make sense to consider a triggerable server software crash a DOS attack?

DDoS (Distributed DoS) is characterised by floods creating a DoS (in all available definitions). A single node causing a flood successfully is kind of rare. But DoS can be caused by a broad range of ...
schroeder's user avatar
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41 votes
Accepted

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

How does one crash a server using (D)DoS? To specifically answer your question, to crash a server using only DDoS you need to target the Application Layer (detailed explanation below). These types of ...
R. Murray's user avatar
  • 754
39 votes

Cloud-based DDoS as a Service

... but they used their own infrastructure It's not really their own infrastructure what they use. They use instead botnets consisting of hijacked systems. These are systems which they p0wn but ...
Steffen Ullrich's user avatar
37 votes
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Is it illegal to DDoS a phishing page?

If you do a DDoS by sending large amounts of traffic to that site, you're very likely creating a lot of collateral damage since other services in (parts of) the network will suffer as well if the ...
Teun Vink's user avatar
  • 6,938
32 votes
Accepted

Is unauthorised deletion an integrity or availability issue?

As pointed out in this (unanswered) question, Availability in CVSSv3 is about how well the web service performs, not whether its data is available: While the Confidentiality and Integrity impact ...
Rhymoid's user avatar
  • 435
23 votes
Accepted

Is deleting files from a database considered a denial of service attack?

Yes, in the sense that anything which "denies service" is a "denial of service". The CIA Triad defines information security as anything which affects Confidentiality, Integrity, or Availability of ...
Mike Ounsworth's user avatar
21 votes
Accepted

Defending against DoS via product reservation

I've seen 2 main solutions: Your products are being reserved for X minutes I've seen notices like this occasionally, but only on places where inventory really matters (usually ticketing sites). I've ...
Conor Mancone's user avatar
20 votes

How to deal with this denial of service attack on an Apache server?

This is a classic SYN flood attack, preventive measures include hashing syn packets, implementing syn cookies checking if the client properly sends RST after an invalid packet sent back to him ddos ...
Rápli András's user avatar
19 votes

Can someone take down Wi-Fi signal?

There are devices that you can buy that will 'jam' a Wi-Fi signal and make it unusable. Also Wi-Fi has different 'channels' that they can be set to run on. If your Wi-Fi is running on a channel that ...
Winter Faulk's user avatar
18 votes

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

A SYN flood isn't about exhausting CPU, it's about exhausting memory. A TCP connection is established through what is known as a "three-way handshake". Traditionally, it works as follows: Client ...
Mark's user avatar
  • 34.7k
18 votes
Accepted

Difference between Amplification and Reflection Attack?

TL;DR: amplification attack is a reflection attack where the reply is larger than the the request. Reflection attack is if the reply is send back to the claimed origin of the request. With a spoofed ...
Steffen Ullrich's user avatar
15 votes

Is it safe to let a user type a regex as a search input?

The main threat in accepting regular expressions will be in your regex execution engine rather than accepting regex itself. I'd expect the threat to be very, very low in any well implemented engine. ...
AJ Henderson's user avatar
  • 42.2k
14 votes

Can a DDoS attack yield any information?

A full answer would be depending on the attack and what would be attacked, so I will keep it general. A DoS can leak information as a side-effect. In earlier times switches were used in networks to ...
H. Idden's user avatar
  • 2,978
14 votes
Accepted

Threshold for DDOS Attack

Nowadays TCP SYN attacks are not common, focus more on UDP amplification attacks over DNS, memcache and other UDP services. On the other hand, if you want to compute the traffic rate you can use the ...
camp0's user avatar
  • 2,274
13 votes

Is it illegal to DDoS a phishing page?

Report the phishing site so browsers can warn the users and show red pages. It's much more efficient and it's completely legal: https://www.google.com/safebrowsing/report_phish/
hunyadym's user avatar
  • 231
13 votes
Accepted

Why are DDos-Attacks still possible?

Blocking attack traffic at the firewall will mitigate an attack designed to overwhelm server CPU or memory resources, but most high-profile attacks simply send a flood of data aiming to exhaust the ...
tlng05's user avatar
  • 10.4k
12 votes
Accepted

How to perform a proper DDoS test in a safe and controlled way?

If you are performing load testing at high packet rates, the most safe way is to isolate it completely from the rest of the network. For example, you can connect two servers by direct 10GBps link ...
Aria's user avatar
  • 2,711
12 votes

Is unauthorised deletion an integrity or availability issue?

I would say it presents a clear Availability issue as the attacker is able to completely remove that specific resource and prevent other users' ability to access. I would also say there is an ...
iainpb's user avatar
  • 4,172
10 votes

Can a DDoS attack yield any information?

Identify shared resources A Denial of Service attack, distributed or not, can be used to successfully identify machines which share resources. If you want to hack a service, you can launch an attack ...
pipe's user avatar
  • 204
10 votes

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

A DDoS usually doesn't crash a server. It overloads it, making it unavaible for normal use. The "best" way to achieve this depends on the function of the server and the way it's configured. There are ...
Teun Vink's user avatar
  • 6,938
10 votes

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

Usually DDoS attacks are what is called layer 4 attacks. These often use SYN floods and are aimed at exhausting all available bandwidth. Just like you can't download movies at an unlimited speed from ...
Anders's user avatar
  • 65.7k
10 votes

How to deal with this denial of service attack on an Apache server?

Limit NEW traffic sudo iptables -A INPUT -p tcp --dport 80 -m state --state NEW -m limit --limit 50/minute --limit-burst 200 -j ACCEPT Limit established traffic sudo iptables -A INPUT -m state --...
GAD3R's user avatar
  • 2,231
10 votes

Does it make sense to consider a triggerable server software crash a DOS attack?

Quite often security is looked at as providing three properties: Availability Integrity Confidentiality In your case, you've found something that allows a user to affect the availability of the ...
sarnold's user avatar
  • 741
9 votes

Can someone take down Wi-Fi signal?

I have used cloning of ESSID and BSSID to do this (set BSSID with ifconfig wlanX hw ether xx:xx:xx:xx:xx:xx. Even if you don't output more power to the clients than their own AP, it will cause ...
user400344's user avatar

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