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PoisonedRefresh: A Fileless Linux Rootkit That Injects PHP Web Shells Into F5 BIG-IP APM Server Memory

Sophos details PoisonedRefresh, a fileless Linux rootkit that injects a memory-resident PHP web shell into F5 BIG-IP APM after exploitation of CVE-2025-53521.

On September 8, 2026, SophosLabs published an analysis of Linux/Agnt-IC (dubbed PoisonedRefresh by ESET) found in compromised F5 BIG-IP Access Policy Manager environments. Initial access leverages CVE-2025-53521, an unauthenticated RCE in BIG-IP APM when an access policy is configured on a virtual server; F5 confirmed exploitation and links the activity to cluster c05d5254, while Shadowserver observed 795 exposed vulnerable endpoints. A first stage hidden in a modified umount binary modifies /usr/sbin/httpd and SELinux configuration and embeds itself in BIG-IP upgrade images for persistence. The second-stage ELF intercepts __libc_start_main, hooks apr_dso_load, and injects a PHP web shell into libphp memory via mmap manipulation, leaving no disk artifacts, and exposes a /bin/bash shell via a local UNIX domain socket instead of a TCP port.

Security Affairs · 7d agoMalware in the wildCVE-2025-53521

Mirai Variant V3G4 Targets IoT Devices

Unit 42 tracked the Mirai variant V3G4 exploiting 13 vulnerabilities across IoT devices and servers from July-December 2022 to build a DDoS botnet.

From July to December 2022, Unit 42 observed three campaigns spreading V3G4, a Mirai botnet variant, by exploiting 13 vulnerabilities, including CVE-2022-26134 in Atlassian Confluence and CVE-2019-15107 in Webmin. The campaigns shared the same C2 domains containing the string 8xl9, nearly identical shell script downloaders, and the same XOR keys, suggesting a single threat actor. The malware brute-forces telnet and SSH credentials, terminates rival botnet processes via a stop list, and receives DDoS commands from its C2. Compromised servers and networking devices are absorbed into the botnet for further attacks.

Palo Alto Unit 42 · 29d agoMalware in the wildCVE-2012-4869CVE-2014-9727CVE-2017-5173+6 CVEs

Bisonal Malware Used in Attacks Against Russia and South Korea

Unit 42 details a Bisonal malware variant, active since 2014, targeting Russian and South Korean defense organizations via PDF-disguised spearphishing emails.

In early May, Unit 42 discovered a campaign delivering a Bisonal malware variant against at least one Russian communications security and cryptography company and one unidentified organization in South Korea. The variant, in the wild since at least 2014, introduces a new C2 cipher and rewritten networking and persistence code, with only 14 samples collected to date. Attackers spoofed Russian state corporation Rostec in spearphishing emails carrying an executable disguised with a PDF icon; the dropper decrypts an RC4-encrypted DLL and establishes persistence via a registry Run key. Bisonal has been used since 2013 against government, military, and defense targets in South Korea, Russia, Japan, and India, alongside successors Bioazih and Dexbia.

Palo Alto Unit 42 · 29d agoMalware in the wild

Mirai Variant MooBot Targeting D

Unit 42 observed the MooBot Mirai variant exploiting four D-Link vulnerabilities to compromise unpatched routers for use in DDoS attacks.

Unit 42 captured attacks exploiting four D-Link remote code execution vulnerabilities: CVE-2015-2051, CVE-2018-6530, CVE-2022-26258, and CVE-2022-28958, with three rated critical at CVSS 9.8. The exploits download the MooBot malware, a Mirai botnet variant, from infrastructure at 159.203.15.179 via wget. Compromised devices fall under full attacker control and can be used for distributed denial-of-service attacks. D-Link has published bulletins for all four flaws, but unpatched devices remain exposed.

Palo Alto Unit 42 · 29d agoMalware in the wildCVE-2015-2051CVE-2018-6530CVE-2022-26258+1 CVEs

HVNC Backdoor Targets LATAM Organizations with Fake Tax and DocuSign Lures

A custom HVNC backdoor is targeting Latin American financial organizations via fake DocuSign and NFe tax-document lures, giving attackers hidden persistent remote access.

ANY.RUN researchers analyzed a multi-stage phishing campaign delivering a custom HVNC backdoor to banking and financial organizations in Latin America. The chain starts with fake DocuSign and NFe tax-document pages that serve per-visitor ZIP archives, followed by an LNK dropper, an NSIS loader, and a 64-bit backdoor masquerading as Windows Update Assistant. The implant provides hidden remote desktop control, keystroke monitoring, Firefox data theft, Startup-folder persistence, and EDR-aware behavior, communicating over TCP/27015.

ANY.RUN · 7d agoMalware in the wild

Shai-Hulud's Reach Just Grew to 469 Credential Locations. Here's What That Means

GitGuardian found the Shai-Hulud infostealer worm now scans 469 credential locations, including CI/CD and AI tool configs, expanding supply-chain risk.

GitGuardian researchers found that a recent Shai-Hulud worm variant scans for credentials across 469 locations in developer environments, CI/CD tooling, cloud configurations, and AI tool configs, up from 189 paths in earlier variants. The worm reuses stolen credentials to pivot from developer workstations to source code, cloud infrastructure, and package publishing channels, turning credential theft into forward-propagating supply chain attacks. The analysis urges defenders to prioritize removing long-lived package publishing tokens in favor of short-lived OIDC-based trusted publishing, citing recent Docker and GitHub Actions improvements.

The Hacker News · 12d agoMalware in the wild1

Analysis of Smoke Loader in New Tsunami Campaign

Fake Japanese Meteorological Agency tsunami warning emails delivered Smoke Loader and AzoRult malware to steal credentials from targets in Japan.

A fake tsunami warning email impersonating Japan's Meteorological Agency asked recipients to click a link on a registered fake agency domain, delivering the commodity loader Smoke Loader to targets in Japan. Smoke Loader, active since 2011, is modular, and its payloads have included banking trojans, ransomware, cryptominers, password stealers, and PoS malware; the campaign later also deployed AzoRult. New samples add junk-jump obfuscation, encrypted network traffic and payload files, a unique machine ID used for tracking and encryption, and PROPagate injection into explorer.exe, with persistence via a Startup folder shortcut and RC4-encrypted C2 communication.

Palo Alto Unit 42 · 29d agoMalware in the wild

Hackers Deploy New SloppyRAT via ClickFix to Enable Ransomware Lateral Movement

Zscaler ThreatLabz reports SloppyRAT, a new Windows RAT delivered via ClickFix lures that supports reconnaissance, reverse SOCKS proxying, and lateral movement for ransomware affiliates.

Zscaler ThreatLabz first observed SloppyRAT in June 2026, delivered through multi-stage ClickFix chains that abuse finger.exe, a renamed curl.exe, and IronPython to load a reflective Python payload. The C++ implant implements 47 PowerShell-like commands via native APIs and direct syscalls, modifies Microsoft Defender settings, and establishes a reverse SOCKS proxy that lets operators pivot into internal networks. It is linked to CastleLoader and CastleRAT components and uses certificate-pinned HTTPS C2 with an EtherHiding fallback via Polygon JSON-RPC. Zscaler assesses it as an intrusion-enablement tool for ransomware operations, though flawed persistence logic suggests the family is still under development.

GBHackersupdated · 5d agofirst · 5d agoMalware in the wild 3 sources

New Mirai-Based Evooo1Bot Botnet Targets Linux Devices

FortiGuard Labs disclosed Evooo1Bot, a Mirai-based Linux botnet active since July 2026 that hijacks routers and IoT devices for DDoS, credential theft, and SOCKS5 proxying.

Fortinet's FortiGuard Labs disclosed Evooo1Bot, a previously undocumented Linux botnet active since July 2026 that reuses Mirai's DDoS engine while adding encrypted C2, SSH brute-force scanning, credential sniffing, and SOCKS5 proxy modules. The bot exploits 18 known CVEs across Alcatel, NETGEAR, Tenda, D-Link, Telesquare, and Mitsubishi devices, some dating back to 2007, and communicates exclusively over port 443 to blend with HTTPS traffic. Compromised hosts can be turned into SOCKS5 relays for anonymous traffic forwarding or monetization via proxy services. The malware uses AES-256-CTR, ChaCha20, and XOR obfuscation with a 28-command administration interface.

Security Affairs · 29d agoMalware in the wildCVE-2007-3010CVE-2016-6277CVE-2018-14558+7 CVEs