Botnet blankets US ISPs in record denial-of-service attack

From the article:

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.

Since its debut more than a year ago, the Aisuru botnet has steadily outcompeted virtually all other IoT-based botnets in the wild, with recent attacks siphoning Internet bandwidth from an estimated 300,000 compromised hosts worldwide.

The hacked systems that get subsumed into the botnet are mostly consumer-grade routers, security cameras, digital video recorders and other devices operating with insecure and outdated firmware, and/or factory-default settings. Aisuru’s owners are continuously scanning the Internet for these vulnerable devices and enslaving them for use in distributed denial-of-service (DDoS) attacks that can overwhelm targeted servers with crippling amounts of junk traffic.

As Aisuru’s size has mushroomed, so has its punch. In May 2025, KrebsOnSecurity was hit with a near-record 6.35 terabits per second (Tbps) attack from Aisuru, which was then the largest assault that Google’s DDoS protection service Project Shield had ever mitigated. Days later, Aisuru shattered that record with a data blast in excess of 11 Tbps.

By late September, Aisuru was publicly flexing DDoS capabilities topping 22 Tbps. Then on October 6, its operators heaved a whopping 29.6 terabits of junk data packets each second at a targeted host. Hardly anyone noticed because it appears to have been a brief test or demonstration of Aisuru’s capabilities: The traffic flood lasted less only a few seconds and was pointed at an Internet server that was specifically designed to measure large-scale DDoS attacks.

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For the past several weeks, ISPs hosting some of the Internet’s top gaming destinations have been hit with a relentless volley of gargantuan attacks that experts say are well beyond the DDoS mitigation capabilities of most organizations connected to the Internet today.

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“The outbound and cross-bound DDoS attacks can be just as disruptive as the inbound stuff,” Dobbin said. “We’re now in a situation where ISPs are routinely seeing terabit-per-second plus outbound attacks from their networks that can cause operational problems.”