Product

Apache

2 mentions in 7 days · 6 in 30 days · 6 total · first seen Sep 2, 2026 · last 6d ago

Timeline6 articles

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 Affairsupdated Sep 10, 11:51 UTC · 5d agofirst Sep 9, 08:50 UTC · 6d agoMalware in the wild 4 sources CVE-2025-53521

F5 BIG-IP APM Malware Injects a PHP Web Shell Into Memory, Evading Disk Scans

Sophos found F5 BIG-IP APM malware that injects a PHP web shell into Apache's memory, evading disk scans, linked to exploited CVE-2025-53521.

Sophos's September 7 analysis describes malware tied to F5's c05d5254 activity that hooks apr_dso_load, modifies the libphp PHP module in memory, and injects a PHP web shell when Apache loads apm_css.php3, full_wt.php3 or webtop_popup_css.php3, leaving on-disk files clean. A separate installer infects /usr/sbin/httpd and umount, runs before Apache starts, disables SELinux (per ESET's related PoisonedRefresh analysis), and opens a local socket at /run/bigtlog.pipe for shell access. The activity is linked to CVE-2025-53521 in BIG-IP APM, rated 9.8 CVSS 3.1, patched in October 2025, added to CISA KEV on March 27, 2026.

The Hacker Newsupdated Sep 10, 11:51 UTC · 5d agofirst Sep 9, 07:36 UTC · 6d agoMalware in the wild 4 sources CVE-2025-53521

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.

BleepingComputerSep 8, 20:08 UTC · 7d agoMalware in the wildCVE-2025-53521

Gambling Goblin Turns Brazilian Government Sites Into SEO Weapons

Check Point links Chinese-speaking cluster Gambling Goblin to SEO-fraud compromises of Brazilian government sites via malicious Apache modules since mid-2025.

Check Point Research dubbed the cluster Gambling Goblin and linked it with medium-to-high confidence to Earth Berberoka, a Chinese-speaking group Trend Micro documented in 2022, citing shared oRAT tooling, Chinese-language artifacts, and domains mimicking trusted tech brands. Custom Apache modules installed on compromised Brazilian government and education servers acted as reverse proxies, routing selected visitors to gambling and sports-betting phishing pages impersonating Google Play, the Microsoft Store, and Amazon while stripping CSP headers. The broader Linux toolkit included the DownPro downloader, AlphaAgent and oRAT backdoors, the 3snake-based PasswordHarvester credential stealer, and an SSH brute-forcer, with operations extending to Vietnamese, Spanish, and English phishing pages.

Infosecurity MagazineSep 2, 14:00 UTC · 13d agoThreat actor

Malicious Apache Modules Hijack Brazilian Government Site Traffic to Push Betting Pages

Check Point links Gambling Goblin, a Chinese-speaking cluster, to malicious Apache modules hijacking Brazilian government servers to promote betting sites.

Check Point Research tracks Gambling Goblin, a Chinese-speaking cluster, installing malicious Apache reverse-proxy modules on compromised Brazilian government and education web servers since mid-2025. The modules divert visitors to gambling and fake app-store pages while stripping the site's security headers, likely for large-scale SEO manipulation. The group's Linux arsenal includes DownPro, AlphaAgent, oRAT, a 3snake-based credential stealer, and SSH brute-forcing tools, and it is tied to Trend Micro's Earth Berberoka. Related SEO-fraud campaigns on .gov.br domains were documented by ESET (GhostRedirector), Palo Alto Networks Unit 42, and Hunt.io.

The Hacker NewsSep 2, 13:44 UTC · 13d agoThreat actor in the wild

Gaming the system: how a Chinese-speaking actor turned Brazilian government sites into an SEO weapon

Check Point identifies Chinese-speaking group Gambling Goblin hijacking Brazilian government domains via malicious Apache modules for SEO-manipulated gambling phishing.

Check Point Research tracks a sustained campaign since mid-2025 against Brazilian government and educational organizations by Gambling Goblin, a Chinese-speaking cybercrime cluster linked to Earth Berberoka. Attackers compile and install malicious Apache modules that silently reverse-proxy visitors to phishing pages impersonating Google Play, Microsoft Store, and Amazon, chaining compromised high-reputation domains to inflate search rankings. The group deploys a heavily obfuscated Linux toolkit including DownPro, AlphaAgent, oRAT, a 3snake-based credential stealer, and SSH brute-forcers, with parallel phishing networks localized for Vietnamese, Spanish, and English victims.

Check Point ResearchSep 2, 10:16 UTC · 13d agoThreat actor

Related CVEsby mentions

CVE-2025-535219.32%
Stack-Based Buffer Overflow in F5 BIG-IP APM Enables Unauthenticated RCE
CVE-2025-53521 is a stack-based buffer overflow (CWE-121) in F5 BIG-IP's Access Policy Manager (APM) that allows remote code execution. The flaw is triggered when a virtual server is configured with an APM access policy and receives specific malicious network traffic; no authentication or user interaction is required per the CVSS 4.0 vector. An attacker who exploits it gains remote code execution on the BIG-IP device, and in observed intrusions attackers have deployed a fileless Linux rootkit (dubbed 'PoisonedRefresh') that injects a PHP web shell into server memory to evade disk-based scanning. Any F5 BIG-IP deployment with an APM access policy configured on a virtual server is potentially affected; versions that have reached End of Technical Support are not evaluated by the vendor. The vulnerability is being actively exploited in the wild — it was added to CISA's Known Exploited Vulnerabilities catalog on 2026-03-27, with active exploitation and in-memory malware campaigns confirmed in press reports, though ransomware use is unknown.
· F5 BIG-IP (BIG-IP Access Policy Manager / APM) KEVlarge

Appears with

vendor ESET 4 malware oRAT 3 malware DownPro 3 malware PoisonedRefresh 3 vendor F5 3 threat actor Gambling Goblin 3 vendor Sophos 3 threat actor Earth Berberoka 3 malware AlphaAgent 3 vendor Trend Micro 2 product libphp 2 vendor Check Point 2 organization Shadowserver Foundation 2 product BIG-IP APM 2 organization Check Point Research 1 malware Xnote 1

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