wsj.com By
Robert McMillan
Sept. 15, 2025 7:00 am ET
Botnets, massive networks of hacked devices, are being used for dangerous attacks, one of which recently set a world record
The Federal Bureau of Investigation recently disrupted a network of hacked devices used by criminals in some of the largest online attacks yet seen. Now those devices have been hacked by someone new to build an even bigger weapon.
Law-enforcement agencies and technology companies are waging a war against increasingly powerful networks of hacked devices, called botnets, that can knock websites offline for a fee. They are used for extortion and by disreputable companies to knock rivals offline, federal prosecutors say.
But lately, a new age of dangerous botnets has arrived, and existing internet infrastructure isn’t prepared, some network operators say. These botnets are leveraging new types of internet-connected devices with faster processors and more network bandwidth, offering them immense power.
The criminals controlling the botnets now have the capabilities to move beyond website takedowns to target internet connectivity and disrupt very large swaths of the internet.
“Before the concern was websites; now the concern is countries,” said Craig Labovitz, head of technology with Nokia’s Deepfield division.
In August, federal prosecutors charged a 22-year-old Oregon man with operating a botnet that had shut down the X social-media site earlier this year.
But the FBI’s takedown last month appeared to have an unwanted consequence: freeing up as many as 95,000 devices to be taken over by new botnet overlords. That led to a free-for-all to take over the machines “as fast as possible,” said Damian Menscher, a Google engineer.
The operators of a rival botnet, called Aisuru, seized control of more than one-fourth of them and immediately started launching attacks that are “breaking records,” he said.
On Sept. 1, the network services company Cloudflare said it had measured an attack that clogged up computer networks with 11.5 trillion bits of junk information per second. That is enough to consume the download bandwidth of more than 50,000 consumer internet connections. In a post to X, Cloudflare declared this attack, known as a distributed denial of service, or DDoS, a “world record” in terms of intensity. Some analysts see it almost as an advertisement of the botnet’s capabilities.
It was one of several dozen attacks of a similar size that network operators have witnessed over the past weeks. The attacks were very short in duration—often lasting just seconds—and may be demonstrations of the Aisuru capabilities, likely representing just a fraction of their total available bandwidth, according to Nokia.
With the world’s increasing dependence on computer networks, denial-of-service attacks have become weapons of war. Russia’s intelligence service, the GRU, used DDoS attacks on Ukraine’s financial-services industry as a way to cause disruption ahead of its 2022 invasion, U.K. authorities have said.
Botnets such as Aisuru are made up of a range of internet-connected devices—routers or security cameras, for example—rather than PCs, and often these machines can only join one botnet at a time. Their attacks can typically be fended off by the largest cloud-computing providers.
One massive network that Google disrupted earlier this year had mushroomed from at least 74,000 Android devices in 2023 to more than 10 million devices in two years. That made it the “largest known botnet of internet-connected TV devices,” according to a July Google court filing.
This network was being used to click billions of Google advertisements in an ad fraud scheme, Google said, but the massive network “could be used to commit more dangerous cybercrimes, such as ransomware” or denial-of-service attacks, the Google filing said.
To date, denial-of-service attacks are spawned from networks like Aisuru that typically include tens of thousands of computers, not millions, making them easier to defend against.
In the past year, a very large botnet that has typically been used for fraud began launching online attacks. Called ResHydra, it is made up of tens of millions of devices, according to Nokia.
Res Hydra represents a whole new level of problem, said Chris Formosa, a researcher with the networking company Lumen’s Black Lotus Labs. Harnessing a botnet of that size would “do extreme damage to a country.”
Executive Summary:
Censys has been tracking this botnet’s global footprint in partnership with findings from both GreyNoise and Sekoia researchers.
To aid in ongoing tracking and research, we’ve launched a live dashboard that tracks exposed ASUS routers showing indicators of AyySSHush compromise. The data updates daily and provides real-time insight into global trends.
Using an AI powered network traffic analysis tool we built called SIFT, GreyNoise has caught multiple anomalous network payloads with zero-effort that are attempting to disable TrendMicro security features in ASUS routers, then exploit vulnerabilities and novel tradecraft in ASUS AiProtection features on those routers.
Irony? Top Score. You love to see it.
Note: This activity was first discovered by GreyNoise on March 18, 2025. Public disclosure was deferred as we coordinated the findings with government and industry partners.
In summary, we are observing an ongoing wave of exploitation targeting ASUS routers, combining both old and new attack methods. After an initial wave of generic brute-force attacks targeting login.cgi, we observe subsequent attempts exploiting older authentication bypass vulnerabilities. Using either of the above methods to gain privileged access to ASUS hardware, we observe payloads exploiting a command injection vulnerability to create an empty file at /tmp/BWSQL_LOG. This existence of a file at this path enables BWDPI logging, a TrendMicro feature embedded in ASUS routers.
Finally, we see remote SSH enabled on a high port TCP/53282 through the official ASUS settings with an attacker controlled public key added to the router’s keyring. This grants the attacker exclusive SSH access. Additionally, because the backdoor is part of the official ASUS settings, it will persist across firmware upgrades, even after the original vulnerability used to gain access has been patched.
The attacker controlled pubkey that is added is:
ssh-rsa AAAAB3NzaC1yc2EAAAABIwAAAQEAo41nBoVFfj4HlVMGV+YPsxMDrMlbdDZJ8L5mzhhaxfGzpHR8Geay/xDlVDSJ8MJwA4RJ7o21KVfRXqFblQH4L6fWIYd1ClQbZ6Kk1uA1r7qx1qEQ2PqdVMhnNdHACvCVz/MPHTVebtkKhEl98MZiMOvUNPtAC9ppzOSi7xz3cSV0n1pG/dj+37pzuZUpm4oGJ3XQR2tUPz5MddupjJq9/gmKH6SJjTrHKSECe5yEDs6c3v6uN4dnFNYA5MPZ52FGbkhzQ5fy4dPNf0peszR28XGkZk9ctORNCGXZZ4bEkGHYut5uvwVK1KZOYJRmmj63drEgdIioFv/x6IcCcKgi2w== rsa 2048
You can find an actively growing list of backdoored hosts here: Censys Search. This list provides detailed information on hosts with the backdoor in question.
Now let’s go threat hunting!
👋 botnet operator, we were watching.
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…
For reference, the 6.3 Tbps attack last week was ten times the size of the assault launched against this site in 2016 by the Mirai IoT botnet, which held KrebsOnSecurity offline for nearly four days. The 2016 assault was so large that Akamai – which was providing pro-bono DDoS protection for KrebsOnSecurity at the time — asked me to leave their service because the attack was causing problems for their paying customers.
Since the Mirai attack, KrebsOnSecurity.com has been behind the protection of Project Shield, a free DDoS defense service that Google provides to websites offering news, human rights, and election-related content. Google Security Engineer Damian Menscher told KrebsOnSecurity the May 12 attack was the largest Google has ever handled. In terms of sheer size, it is second only to a very similar attack that Cloudflare mitigated and wrote about in April.
After comparing notes with Cloudflare, Menscher said the botnet that launched both attacks bears the fingerprints of Aisuru, a digital siege machine that first surfaced less than a year ago. Menscher said the attack on KrebsOnSecurity lasted less than a minute, hurling large UDP data packets at random ports at a rate of approximately 585 million data packets per second.
“It was the type of attack normally designed to overwhelm network links,” Menscher said, referring to the throughput connections between and among various Internet service providers (ISPs). “For most companies, this size of attack would kill them.”
In April 2025, the Global Threat Hunting system of NSFOCUS Fuying Lab detected a significant increase in the activity of a new Botnet Trojan developed based on Go language. Given that many of its built-in DDoS attack methods are HTTP-based, Fuying Lab named it HTTPBot. The HTTPBot Botnet family first came into our monitoring scope in August 2024. Over the past few months, it has expanded aggressively, continuously leveraging infected devices to launch external attacks. Monitoring data indicates that its attack targets are primarily concentrated in the domestic gaming industry. Additionally, some technology companies and educational institutions have also been affected. The attack of this Botnet family is highly targeted, with attackers employing a periodical and multi-stage attack strategy to conduct continuous saturation attacks on selected targets.
In terms of technical implementation, the HTTPBot Botnet Trojan uses an “attack ID” to precisely initiate and terminate the attack process. It also incorporates a variety of innovative DDoS attack methods. By employing highly simulated HTTP Flood attacks and dynamic feature obfuscation techniques, it circumvents traditional rule-based detection mechanisms, including but not limited to the following detection bypass mechanisms:
FortiGuard Labs recently discovered a new botnet propagating through TOTOLINK devices. Learn more about this malware targeting these devices.
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Russian threat actors combine domain name vulnerabilities with hidden router proxy techniques to scale their attacks while remaining shielded from detection.
The Qualys Threat Research Unit has uncovered a large-scale, ongoing operation within the Mirai campaign, dubbed Murdoc Botnet.
Since the end of 2024, we have been continuously monitoring large-scale DDoS attacks orchestrated by an IoT botnet exploiting vulnerable IoT devices such as wireless routers and IP cameras.
U.S. officials say the sanctioned Chinese firm provided botnet infrastructure for the China-backed hacking group Flax Typhoon
FortiGuard Labs recently noticed that attackers still use and deliver two different botnets via D-Link exposing a HNAP interface weakness. Learn more.
Discover the latest insights on the Quad7 / 7777 botnet in our detailed analysis. Learn about the expansion of this resilient threat, its targeting patterns, and proactive measures to defend against compromised routers. Stay informed with our up-to-date findings and recommendations.
Uncover the secrets of the Quad7 botnet and its ever-evolving toolset. Learn about the new backdoors and protocols used by these operators.
New Gorilla botnet launches over 300,000 DDoS attacks globally, exploiting IoT devices and Apache Hadoop flaws.
Uncover the secrets of the Quad7 botnet and its ever-evolving toolset. Learn about the new backdoors and protocols used by these operators.
The Akamai Security Intelligence and Response Team (SIRT) has observed a botnet campaign that is abusing several previously exploited vulnerabilities, as well as a zero-day vulnerability discovered by the SIRT.
CVE-2024-7029 (discovered by Aline Eliovich) is a command injection vulnerability found in the brightness function of AVTECH closed-circuit television (CCTV) cameras that allows for remote code execution (RCE).
Once injected, the botnet spreads a Mirai variant with string names that reference the COVID-19 virus that has been seen since at least 2020.
We have included a list of indicators of compromise (IOCs) to assist in defense against this threat.
Aqua Nautilus researchers discovered a new variant of Gafgyt targeting machines with weak SSH passwords.
Sekoia.io investigated the mysterious 7777 botnet (aka. Quad7 botnet), published by the independent researcher Gi7w0rm inside the “The curious case of the 7777 botnet” blogpost.
This investigation allowed us to intercept network communications and malware deployed on a TP-Link router compromised by the Quad7 botnet in France.
To our understanding, the Quad7 botnet operators leverage compromised TP-Link routers to relay password spraying attacks against Microsoft 365 accounts without any specific targeting.
Therefore, we link the Quad7 botnet activity to possible long term business email compromise (BEC) cybercriminal activity rather than an APT threat actor.
However, certain mysteries remain regarding the exploits used to compromise the routers, the geographical distribution of the botnet and the attribution of this activity cluster to a specific threat actor.
The insecure architecture of this botnet led us to think that it can be hijacked by other threat actors to install their own implants on the compromised TP-Link routers by using the Quad7 botnet accesses.
