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Hackers breach F5 BIG-IP APM devices to deploy Linux rootkit

Sophos analyzed a Linux rootkit on F5 BIG-IP APM devices that injects a fileless PHP web shell, likely after CVE-2025-53521 exploitation.

Sophos analyzed a Linux rootkit targeting F5 BIG-IP APM environments, also tracked by ESET as PoisonedRefresh, which hijacks Apache's apr_dso_load module loader to inject a fileless PHP web shell into memory. The implant intercepts __libc_start_main, hides strings with RC4, creates a password-protected local UNIX socket backdoor for interactive Bash access, and persists across BIG-IP upgrade images while modifying SELinux configuration. It is likely a second-stage payload following exploitation of CVE-2025-53521, a critical RCE flaw F5 reclassified from a DoS issue in March. The ShadowServer Foundation tracked 795 F5 BIG-IP APM endpoints exposed online.

BleepingComputer · 8d agoMalware in the wildCVE-2025-53521

Top 10 Best Ransomware Protection Solutions in 2026

A 2026 buyer's guide ranks ten ransomware protection tools by kill-chain role as extortion shifts from encryption to data theft.

The roundup organizes defenses across the ransomware kill chain: prevention-grade EPP/EDR platforms, containment layers, rollback specialists, and immutable recovery. Recommended products include CrowdStrike, Microsoft Defender, Sophos, SentinelOne, Bitdefender, Trend Micro, Halcyon, Huntress, and Malwarebytes. It stresses that many crews now extort on stolen data without encrypting, making exfiltration detection and response speed as important as rollback.

Cyber Security News · 6d agoIndustry1

Hackers deploy Linux rootkit on F5 BIG-IP APM devices, hiding web shell in memory

Sophos analyzed a Linux rootkit, tracked as PoisonedRefresh, on hacked F5 BIG-IP APM devices hiding an in-memory web shell linked to exploited CVE-2025-53521.

Sophos and ESET analyzed an implant (named PoisonedRefresh by ESET) deployed on compromised F5 BIG-IP APM appliances, which serves enterprise, financial, government, and public sector deployments. The second-stage payload intercepts __libc_start_main, hooks Apache's APR module loader (apr_dso_load), RC4-encodes key strings, and rewrites PHP file reads in memory to embed a web shell inside legitimate scripts like apm_css.php3, full_wt.php3, and webtop_popup_css.php3, leaving on-disk files unchanged. A related installer component infects /usr/sbin/httpd, persists across BIG-IP upgrade images, modifies SELinux configuration, and deploys the payload. The malware also creates a Unix domain socket at /run/bigtlog.pipe that hands authenticated local connections to /bin/bash; F5 links the activity to CVE-2025-53521, an unauthenticated RCE in BIG-IP APM already exploited in the wild.

Help Net Security · 7d agoMalware in the wildCVE-2025-535211

The 12 Best Antivirus (Endpoint Protection) Software for Business, Compared and Priced

GBHackers compares 12 business antivirus products on detection, EDR depth, pricing, and platform coverage, ranking CrowdStrike and Bitdefender joint top at 8.8.

The roundup scores 12 enterprise endpoint protection vendors across detection, EDR depth, management, pricing transparency, and platform coverage. CrowdStrike and Bitdefender tie at 8.8, with Microsoft Defender for Endpoint scoring 8.5 and noted as effectively free for Microsoft 365 E5 licensees. The piece also flags that Kaspersky cannot legally be sold in the US and that Panda and Webroot now sit under WatchGuard and OpenText respectively.

GBHackers · 8d agoIndustry 2 sources1

Attackers impersonate popular AI brands to spread malware

Sophos documented 38 MDR cases where attackers impersonated AI brands like Claude and Perplexity to deliver infostealers and backdoors.

Sophos X-Ops analyzed 12 months of MDR cases and confirmed 38 incidents involving AI. Software impersonation accounted for 30 cases, with Claude impersonated in 26; fake installers used an 'InstallFix' technique delivering mshta commands, in-memory payloads, and process hollowing. Malicious browser extensions posing as AI assistants, including a fake Perplexity extension with 10,000 installs, acted as infostealers. In one case, attackers used a Claude coding agent to develop a Rust remote access trojan communicating over Slack after an SQL injection compromise.

Help Net Security · 27d agoThreat actor in the wild

MSPs say nearly half their customers rely on them for CISO services

Sophos survey finds MSPs act as CISOs for an average 46% of customers, mostly with partial compliance offerings and fragmented manual reporting.

A Sophos survey found MSPs estimate that 46% of their customers rely on them to act as CISOs, and most providers deliver only four to six of seven measured compliance services. More than half say they manage customers' full compliance programs, while compliance requirements influence roughly half of customers' security purchases. Nearly nine in ten providers use software, but most juggle multiple tools that cannot feed a central reporting platform, forcing staff to combine data manually. Providers estimated a unified platform would cut time spent on posture, compliance and reporting by about half; Sophos sells CISO Advantage via its Sophos Fusion system for this work.

Help Net Security · 1d agoIndustry

Uncensored AI sold on hacking forum as alternative to ChatGPT and Claude jailbreaks

Sophos found Luciferus, an uncensored AI subscription service likely built on Qwen, sold on the Exploit forum and capable of generating working malware code.

Sophos Counter Threat Unit found an ad for 'Luciferus' posted August 24 on the Exploit forum by a persona named 'Optimus_Prime', claiming a proprietary 120-billion-parameter model that answers requests without ethical restrictions. Sophos assesses with low confidence it is based on Alibaba's open-source Qwen family. Forum tiers cost $35-$75/month, while the website lists Junior/Middle/Pro tiers at $22-$47.14; a test prompt on the Junior tier returned Python remote access trojan source code. Sophos warns such services lower barriers for less skilled cybercriminals and outlast jailbroken mainstream LLMs.

Help Net Security · 1d agoAI safety & security