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The FritzFrog botnet re-emerged after a lull, with Akamai observing renewed activity beginning in December 2021 and SecurityWeek reporting at least 1,500 infected hosts worldwide. The Golang-based malware remains memory-resident and uses a proprietary peer-to-peer command-and-control model, allowing compromised systems to act as decentralized control nodes. Researchers said the botnet primarily targets SSH-accessible servers through brute-force credential attacks, with victims concentrated in China, Central Europe, and the United States.
The newer variant, referred to as FritzFrog v2, added capabilities including Tor proxy chain support, use of a public SCP library for self-propagation, and logic to avoid low-resource systems and suspected sinkholes. Akamai said the malware drops a file that listens on port 1234, scans internet hosts on 22 and 2222, and now disguises its process as apache2 instead of earlier names such as ifconfig or nginx; observed attack volume peaked at roughly 500 incidents per day. Researchers also noted indicators that may point to a China-based actor, or one attempting to appear Chinese.
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Akamai Threat Labs observed renewed FritzFrog attacks beginning in early December 2021 against its global sensor network, marking the return of the botnet after a lull. The newer variant used updated behavior, including dropping a file that listened on port 1234 and scanned internet IPs on ports 22 and 2222.
Guardicore Labs publicly disclosed technical details on FritzFrog, bringing the botnet to wider attention. After this publication, researchers observed a decline in attack activity.
The FritzFrog botnet first emerged as a Golang-based, memory-resident peer-to-peer malware targeting SSH servers.
Akamai warned that the renewed FritzFrog campaign had infected at least 1,500 hosts globally, with victims concentrated in China, Central Europe, and the United States. The company also described new capabilities such as Tor proxy chain functionality, SCP-based self-propagation, and logic to avoid low-resource systems and suspected sinkholes.
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Researchers reported a previously undocumented Linux botnet dubbed **SSHStalker** that has compromised roughly **7,000** systems by combining **SSH credential brute-forcing/scanning** with **legacy (circa-2009) exploit chains** and highly automated staging. The activity was observed over multiple weeks via SSH honeypots, with intrusions characterized by rapid deployment, on-host compilation, and automated enrollment into command infrastructure, indicating an operation optimized for mass compromise rather than targeted intrusion. SSHStalker uses **IRC-based command-and-control** and a mixed toolkit that includes C-based bots, Perl scripts, and known botnet malware families such as **Tsunami** and **Keiten**. Reporting highlighted an unusual “**dormant persistence**” pattern: infected hosts are kept under control without immediate visible monetization or impact operations, despite having capabilities associated with **DDoS** and **cryptomining**. Persistence is described as noisy but effective, including **cron-based relaunch** behavior that can restore the malware within about a minute after disruption, suggesting the operator may be staging infrastructure or retaining access for future use.
Jun 29, 2026
Researchers linked multiple Linux intrusions to a Romanian-speaking threat cluster that brute-forced weak SSH credentials, compromised servers and network devices at scale, and deployed a Perl-based **Shellbot** with IRC command-and-control. Trend Micro found infrastructure capable of generating target lists covering roughly **80 million IP addresses**, logs indicating more than **65,000 potentially compromised hosts**, and tooling including the **Haiduc** SSH brute-forcer, process-masquerading utility **Faker**, privilege-escalation exploits such as `CVE-2017-16995` and Dirty Cow variants, and high-availability C2 built with CARP. Bitdefender separately tied a likely Romanian group to Linux-focused scanning, SHC-obfuscated loaders, Discord webhook reporting, a customized Perl IRC bot, and a Golang SSH bruteforcer offered in a SaaS-like model, with monetization centered on **Monero** mining via customized **XMRig** payloads. Additional reporting showed the campaign’s tradecraft remained active across traditional servers and cloud-native environments. JPCERT/CC documented attackers using stolen SSH access to move laterally, install **XMRig**, hide mining with **XHide**, tamper with logs, and continue scanning for new SSH targets, while Sysdig observed Shellbot compromise a Tomcat container through brute-forced default credentials, download multi-architecture payloads, establish persistence, erase traces, and receive commands for file transfer, port scanning, data exfiltration, and **DDoS** attacks. Together, the reports describe a long-running Linux-focused operation that blends brute-force access, worm-like propagation, cryptojacking, and botnet functionality across exposed infrastructure.
Aug 15, 2026
Microsoft and CUJO AI reported that **Zerobot**, a Go-based malware-as-a-service botnet, expanded its compromise of IoT and internet-facing systems by combining brute-force attacks on weak `SSH` and `Telnet` credentials with exploitation of more than 20 known vulnerabilities. The malware targeted routers, firewalls, IP cameras, web servers, and enterprise software, with observed exploitation including `CVE-2021-42013` in Apache, `CVE-2022-33891` in Apache Spark, **Spring4Shell**, and **F5 BIG-IP** flaws. Researchers said the botnet delivered architecture-specific binaries or a `zero.sh` script from attacker-controlled infrastructure and added infected devices to a distributed denial-of-service network. The newer **Zerobot 1.1** variant added multiple DDoS attack methods, Linux and Windows-capable samples, and persistence mechanisms for both platforms, while also attempting to remove rival malware such as **Mozi**, **Kaiten**, **Sora**, **Phantom**, **Nbrute**, and `minerd`. Investigators linked activity to infrastructure including the domain `zero.sudolite.ml` and IP addresses `176.65.137.5` and `176.65.137.6`, and noted that one associated domain was reportedly among domains tied to DDoS-for-hire services seized by the FBI. Researchers also found some exploit routines were malformed or mislabeled, suggesting the botnet was still under active development even as it broadened propagation and evasion behavior.
Aug 15, 2026