Questions tagged [ddos]

Distributed Denial Of Service (DDOS) is the intentional paralyzing of a computer network by flooding it with data sent simultaneously from many individual computers (so-called zombies) which are used to stage DDOS attacks

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Unkown attack on linux server wordpress website

I have a WordPress site. Recently under a serious DDoS attack. For this WordPress site I use nginx, varnish and apache in the backend. A part of access log shows this: 24.41.213.36 - - [23/Jun/...
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What's the main constituent part of botnet?

Is the botnet controlled broiler of servers or personal PCs? We know the botnet can be controlled to DDoS attack, but what's the main constituent part of botnet? I know the botnet's element maybe PC,...
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47 views

Why is GRE tunneling is needed when having a BGP based solution against DDoS?

I understand that GRE tunneling is very handy when sending the data back to the client after scrubbing because it's designed to ensure that the data is sent reliably by initiating a private point-to-...
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What can be done against DDoS attacks when I just have only small number of “known” clients reaching a server?

Description of the Situation: Let's say 1000 "known" clients/workers are collecting time-sensitive data from the field and sending to a server. Therefore, we need to secure the server from DDoS ...
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260 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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84 views

Cloud based solution to prevent DDoS attack on multiplayer game server?

I built an architecture below: How does it work (and if it's possible) Assuming your game server currently runs on Node 1 and then Node 1 gets a successful DDoS attack. Your cloud system has ...
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132 views

519 tls handshake attempts in 3 seconds, with 415 within one second, was this a DDOS attack?

This morning our webserver was unresponsive to say the least. The connection was lost, the database connection we have was sluggish to say the least. I was forced to do a reboot via the remote hosting ...
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215 views

a mysterious & pointless long-term hacking attempt?

It seems that I am the target of a mysterious ongoing hacking attempt. I have several domain names, most of which are currently parked & pointed at a single ‘main’ website. For the last couple ...
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293 views

Thousands of 28000 “no pg_hba.conf entry for host” logs from Postgres - is this an attack?

Since yesterday afternoon my production Postgres database hosted on Amazon EC2 has been logging thousands of errors (averaging one or two per second) that all follow the format: sql_error_code = ...
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385 views

Public API security: authentication vs. rate limiting etc

We are raising a SaaS product that allows businesses to setup and orchestrate selling of a certain class of goods/services. This product has an API in its core and an ecosystem of various apps around ...
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Which metrics can be considered in the context of DDoS-similarity analysis?

What data should be collected if i want to bind two different DDoS-attacks? In example i want to build a model, which will calculate the similarity of two DDoS-attacks. The basic metrics should be: ...
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233 views

How did facebook DDoS me?

About 1 day ago my router was being DDoS by some people and one of the ip addreses was Facebook's. Can anyone explain this? [DoS Attack: ACK Scan] from source: 31.13.65.50, port 443, Saturday, ...
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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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How does IP traceback works? [closed]

In part prompted by the difficulties in determining the true origins of DDOS attacks featuring spoofed IP addresses, researchers have attempted to develop the concept of IP traceback: determining ...
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64 views

Blockchain + shared unused bandwidth as the proxy front = ddos mitigated?

Pentesting the new webapp that we have developed before having an external source have a go at it and give us a risk assessment. Now we have come to the portion right at the end; DDOS. For the most ...
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133 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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161 views

Please help diagnose multiple incoming packets

We have an internet-facing router and it is significantly slowed down. We investigated the network traffic and came up with following information: All the packet size is same (i.e. 40 bytes) All ...
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186 views

Website is behaving strangely - was it attacked?

Our website was behaving strangely. Sometime it was down and nothing was accessible. Sometime it started loading but pages browsing was too slow. We checked apache logs and found the below ...
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259 views

Do major ISPs still ignore IP spoofing?

I was reading this question: Why don't ISPs filter on source address to prevent spoofing? and based on those answers, ISPs ignore it because of the overhead of checking for spoofing. But that ...
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60 views

How link flooding DDoS attack remain undetected?

I read some explains or paper about link flooding DDoS attack, which is new relatively. For example "employs legitimate, low-density flows to flood a group of selected links. Therefore, these ...
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311 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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113 views

Firewall Showing 1,000's Of Strange GET Parameters Being Sent To Login Page?

So I woke up today, and checked my Firewall Events on CloudFlare for my website like I do normally. Most of the time I'll just see thousands of failed SQL injection attempts, but this morning I was ...
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372 views

Suspicious “100% guaranteed” web hosting security package

Notes: I have very limited knowledge and experience in this field. My boss does not want to spend a penny more that what we already paid for. The website has a form that sends a message to our email ...
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166 views

Why the DDoS attacker need many zombie machine for attack? [duplicate]

Why the DDoS attacker need many zombie machine for attack? if attacker has one machine for generate enough attack traffic for its business(DoS), does it still need many zombie machine(DDoS)? what's ...
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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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225 views

Is it possible to defend against a backscatter attack?

Yesterday, some spammer on the other side of the world decided to send out a ton of phishing mails with my business mail address as both From address and envelope sender. The usual best practices are ...
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Will More vCPU's and RAM Help Protect Against Some Smaller Scale DDoS Attacks?

Obviously having more vCPU's (virtual CPU's) and more RAM by them self won't be able to alone help stop and/or prevent a DDoS attack, but let's say after a DDoS attack is finished and/or slowing down ...
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454 views

Amazon EC2 Abuse Report

My company recently received an email from Amazon which notified us of malicious activities occurring on our running EC2 Instance. The email states: We observed machines under your control ...
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266 views

Can I assume that an empty user agent will always be a robot?

I want to prevent robots flooding my website and I'm thinking about a ban in these cases... Can I assume that an empty user agent will always be a robot?
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526 views

How to detect when one or more devices in my local network have become DDOS attack nodes?

I have a home network, big family, with around 20 devices on it at any given time. It seems like every year or so, some device gets a virus or a security flaw is revealed, and the device starts ...
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622 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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TCP protocol Denial-of-service attack [closed]

There are different types of DDoS attacks. As defined by TechTarget, Network-centric or volumetric attacks overload a targeted resource by consuming available bandwidth with packet floods. Protocol ...
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153 views

How do you detect a Memcached DDoS attack on your server?

In terms of early detection, how could a sysadmin detect that a Memcached DDoS attack took place?
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171 views

What is the difference between DNS flood attack and UDP flood attack?

As title says, what is the difference between DNS flood attack and UDP flood attack? Plus, do they only exhaust the network bandwidth or do they also exhaust the server-side assets such as CPU, ...
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320 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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241 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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648 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 ...
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220 views

What Are the Algorithm and techniques of IP Traceback?

In most of the cases the cyber attacks such as a DDoS attack or other kinds, it is sometimes hard/impossible to identify the real source IP addresses. This is because when you review the logs and ...
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56 views

Why does Spamhaus' CBL blocklist return records for 1.1.1.1 and 8.8.8.8?

I'm looking up ips with the following code import dns.resolver resolver = dns.resolver.Resolver() resolver.timeout = 0.10 resolver.lifetime = 0.10 resolver.nameservers = ['127.0.0.53'] searchIp = '8....
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429 views

Use mining to prevent DDOS attacks on websocket: Is this a viable solution?

I'm thinking whether the following way is a good way to completely and totally prevent ddos on my server. My idea is to use the same mechanism of cryptocurrency mining (bitcoin, with sha256 or any ...
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125 views

Why do websites like Truecaller make you prove that you are not a robot after a limited number of searches?

I used Truecaller for searching for a number but after around 20 to 25 searches they started asking me to prove that I am not a robot. Is this for protecting their website from a DDoS attacks or is it ...
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134 views

Are HTTP calls from hundreds of ips in the same subnet malicious?

I've been getting hit everyday with 50-100M calls to my API and I'm trying to identify the subnets that are the sources. I found by running a match in redis (where all requests from the last 24hrs ...
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160 views

How SSL/TLS handshake happens when we use Cloudflare Service?

I was reading about the offerings of the Cloudflare and then I read about the working of Cloudflare. Based on my understanding, the domain name of my website(alice.com) is resolved to the IP address ...
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114 views

How does LBaaS / DBaaS or “auto-scaling” help protect from DoS?

I ask this question as a follow up to this question in which I asked how I could protect from the simplest types of DoS attacks (say single-machine / up to 5 machines network level DoS attack) without ...
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174 views

packets characteristics (src,dst ports) of a DDos amplification attacks

In a DDoS amplification attack, say NTP flooding, an attacker uses a botnet network in order to query multiple NTP servers on port 123, spoofing the source address using the address of the victim/...
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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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57 views

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 ...
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2k views

Does google's reCAPTCHA mitigate DDoS attacks?

I was reading this post from half a decade ago about the pros and cons of using captcha during a DDoS attack (How does CAPTCHA mitigate DDoS attacks?) At that time there seems to be basically 2 ...
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226 views

DNS flood vs DNS Amplification attack: How is one considered a network/transport layer attack and the other a application layer attack?

I am reading a survey on DDoS attacks and they describe how these attacks can be classified by either Network/Transport level attacks and Application level attacks. In their examples, they classify ...
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163 views

How to protect a website from DDoS without a CDN? [closed]

I have basic knowledge in Bash and with that knowledge I rented a remote machine in a mostly-self-managed hosting platform (DigitalOcean) and raised a LEMP environment on which I have a website. I ...