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Denial of service (DoS) is an attack that makes a system, network, or application unavailable by exhausting resources or triggering failure. Floods can consume bandwidth, connection state, CPU, memory, or request-processing capacity; a software defect may instead be exploited to crash a service. A distributed denial-of-service (DDoS) attack generates traffic from many systems, increasing volume and complicating source-based blocking. The material security impact is loss of availability for users and dependent services, including websites, APIs, DNS, and operational systems.

Mitigation should match the bottleneck. Rate limits, request validation, connection protections, caching, and service isolation can reduce application and state-exhaustion attacks; volumetric traffic generally needs filtering or absorption upstream of the network. Monitoring should distinguish abnormal request patterns from ordinary load and alert on saturation, while tested failover, traffic diversion, and restoration procedures limit outage duration. Vulnerability management and timely patching reduce DoS caused by remotely triggerable crashes, but do not replace capacity planning and resilience testing.

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Canadian authorities on Wednesday arrested a 23-year-old Ottawa man on suspicion of building and operating Kimwolf, a fast spreading Internet-of-Things botnet that enslaved millions of devices for use in a series of massive distributed denial-of-service (DDoS) attacks over the past six months. KrebsOnSecurity publicly named the suspect in February 2026 after the accused launched a volley of DDoS, doxing and swatting campaigns against this author and a security researcher. He now faces criminal hacking charges in both Canada and the United States.

Krebs on Security 2 months, 2 weeks ago

Anti-DDoS Firm Heaped Attacks on Brazilian ISPs

A Brazilian tech firm that specializes in protecting networks from distributed denial-of-service (DDoS) attacks has been enabling a botnet responsible for an extended campaign of massive DDoS attacks against other network operators in Brazil, KrebsOnSecurity has learned. The firm's chief executive says the malicious activity resulted from a security breach and was likely the work of a competitor trying to tarnish his company's public image.

Krebs on Security 3 months, 4 weeks ago

Feds Disrupt IoT Botnets Behind Huge DDoS Attacks

The U.S. Justice Department joined authorities in Canada and Germany in dismantling the online infrastructure behind four highly disruptive botnets that compromised more than three million hacked Internet of Things (IoT) devices, such as routers and web cameras. The feds say the four botnets -- named Aisuru, Kimwolf, JackSkid and Mossad -- are responsible for a series of recent record-smashing distributed denial-of-service (DDoS) attacks capable of knocking nearly any target offline.

Krebs on Security 4 months, 2 weeks ago

Who is the Kimwolf Botmaster “Dort”?

In early January 2026, KrebsOnSecurity revealed how a security researcher disclosed a vulnerability that was used to assemble Kimwolf, the world's largest and most disruptive botnet. Since then, the person in control of Kimwolf -- who goes by the handle "Dort" -- has coordinated a barrage of distributed denial-of-service (DDoS), doxing and email flooding attacks against the researcher and this author, and more recently caused a SWAT team to be sent to the researcher's home. This post examines what is knowable about Dort based on public information.

Krebs on Security 5 months, 4 weeks ago

Kimwolf Botnet Lurking in Corporate, Govt. Networks

A new Internet-of-Things botnet called Kimwolf has spread to more than 2 million devices, forcing infected systems to participate in massive distributed denial-of-service (DDoS) attacks and to relay other malicious and abusive Internet traffic. Kimwolf's ability to scan the local networks of compromised systems for other IoT devices to infect makes it a sobering threat to organizations, and new research reveals Kimwolf is surprisingly prevalent in government and corporate networks.

Krebs on Security 8 months, 2 weeks ago

Aisuru Botnet Shifts from DDoS to Residential Proxies

Aisuru, the botnet responsible for a series of record-smashing distributed denial-of-service (DDoS) attacks this year, recently was overhauled to support a more low-key, lucrative and sustainable business: Renting hundreds of thousands of infected Internet of Things (IoT) devices to proxy services that help cybercriminals anonymize their traffic. Experts says a glut of proxies from Aisuru and other sources is fueling large-scale data harvesting efforts tied to various artificial intelligence (AI) projects, helping content scrapers evade detection by routing their traffic through residential connections that appear to be regular Internet users.

Krebs on Security 9 months, 1 week ago

DDoS Botnet Aisuru Blankets US ISPs in Record DDoS

The world's largest and most disruptive botnet is now drawing a majority of its firepower from compromised Internet-of-Things (IoT) devices hosted on U.S. Internet providers like AT&T, Comcast and Verizon, new evidence suggests. Experts say the heavy concentration of infected devices at U.S. providers is complicating efforts to limit collateral damage from the botnet's attacks, which shattered previous records this week with a brief traffic flood that clocked in at nearly 30 trillion bits of data per second.

Krebs on Security 10 months, 4 weeks ago

Oregon Man Charged in ‘Rapper Bot’ DDoS Service

A 22-year-old Oregon man has been arrested on suspicion of operating "Rapper Bot," a massive botnet used to power a service for launching distributed denial-of-service (DDoS) attacks against targets -- including a March 2025 DDoS that knocked Twitter/X offline. The Justice Department asserts the suspect and an unidentified co-conspirator rented out the botnet to online extortionists, and tried to stay off the radar of law enforcement by ensuring that their botnet was never pointed at KrebsOnSecurity.

Krebs on Security 1 year, 1 month ago

KrebsOnSecurity Hit With Near-Record 6.3 Tbps DDoS

KrebsOnSecurity last week was hit by a near record distributed denial-of-service (DDoS) attack that clocked in at more than 6.3 terabits of data per second (a terabit is one trillion bits of data). The brief attack appears to have been a test run for a massive new Internet of Things (IoT) botnet capable of launching crippling digital assaults that few web destinations can withstand. Read on for more about the botnet, the attack, and the apparent creator of this global menace.

Krebs on Security 1 year, 9 months ago

Sudanese Brothers Arrested in ‘AnonSudan’ Takedown

The U.S. government on Wednesday announced the arrest and charging of two Sudanese brothers accused of running Anonymous Sudan (a.k.a. AnonSudan), a cybercrime business known for launching powerful distributed denial-of-service (DDoS) attacks against a range of targets, including dozens of hospitals, news websites and cloud providers. One of the brothers is facing life in prison for allegedly seeking to kill people with his attacks.

Krebs on Security 2 years, 1 month ago

Stark Industries Solutions: An Iron Hammer in the Cloud

Two weeks before Russia invaded Ukraine in February 2022, a large, mysterious new Internet hosting firm called Stark Industries Solutions materialized and quickly became the epicenter of massive distributed denial-of-service (DDoS) attacks on government and commercial targets in Ukraine and Europe. An investigation into Stark Industries reveals it is being used as a global proxy network that conceals the true source of cyberattacks and disinformation campaigns against enemies of Russia.

Krebs on Security 3 years, 2 months ago

Feds Take Down 13 More DDoS-for-Hire Services

The U.S. Federal Bureau of Investigation (FBI) this week seized 13 domain names connected to “booter” services that let paying customers launch crippling distributed denial-of-service (DDoS) attacks. Ten of the domains are reincarnations of DDoS-for-hire services the FBI seized in December 2022, when it charged six U.S. men with computer crimes for allegedly operating booters.

Krebs on Security 3 years, 3 months ago

German Police Raid DDoS-Friendly Host ‘FlyHosting’

Authorities in Germany this week seized Internet servers that powered FlyHosting, a dark web service that catered to cybercriminals operating DDoS-for-hire services. Fly Hosting first advertised on cybercrime forums in November 2022, saying it was a Germany-based hosting firm that was open for business to anyone looking for a reliable place to host malware, botnet controllers, or DDoS-for-hire infrastructure.

Most people who operate DDoS-for-hire services attempt to hide their true identities and location. Proprietors of these so-called “booter” or “stresser” services — designed to knock websites and users offline — have long operated in a legally murky area of cybercrime law. But until recently, their biggest concern wasn’t avoiding capture or shutdown by the feds: It was minimizing harassment from unhappy customers or victims, and insulating themselves against incessant attacks from competing DDoS-for-hire services. And then there are booter store operators like John Dobbs, a 32-year-old computer science graduate student living in Honolulu, Hawaii. For at least a decade until late last year, Dobbs openly operated IPStresser[.]com, a popular and powerful attack-for-hire service that he registered with the state of Hawaii using his real name and address. Likewise, the domain was registered in Dobbs’s name and hometown in Pennsylvania. The only work experience Dobbs listed on his resume was as a freelance developer from 2013 to the present day. Dobbs’s resume doesn’t name his booter service, but in it he brags about maintaining websites with half a million page views daily, and “designing server deployments for performance, high-availability and security.” In December 2022, the U.S. Department of Justice seized Dobbs’s IPStresser website and charged him with one count of aiding and abetting computer intrusions. Prosecutors say his service attracted more than two million registered users, and was responsible for launching a staggering 30 million distinct DDoS attacks.

Krebs on Security 3 years, 7 months ago

Six Charged in Mass Takedown of DDoS-for-Hire Sites

The U.S. Department of Justice (DOJ) today seized four-dozen domains that sold “booter” or “stresser” services — businesses that make it easy and cheap for even non-technical users to launch powerful Distributed Denial of Service (DDoS) attacks designed knock targets offline. The DOJ also charged six U.S. men with computer crimes related to their alleged ownership of the popular DDoS-for-hire services.