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A financially motivated threat actor tracked as INJ3CTOR3 has been observed exploiting CVE-2025-64328, a post-authentication command-injection flaw in the FreePBX Endpoint Manager administrative interface, to deploy a persistent PHP web shell dubbed EncystPHP. The activity began in early December 2025 and enables attackers to execute arbitrary commands (as the asterisk user) and progress to full administrative control of compromised VoIP environments, supporting follow-on abuse such as unauthorized call generation and toll fraud.
FortiGuard Labs reported the campaign’s infrastructure and delivery chain, including downloads of an EncystPHP dropper from 45[.]234[.]176[.]202 (domain crm[.]razatelefonia[.]pro), a site masquerading as a VoIP management portal with a login page; requests to the new/ path reportedly redirect to an additional dropper (k.php). The observed exploitation traffic originated from Brazil and targeted an environment managed by an Indian technology services provider; affected versions were reported as FreePBX Endpoint Manager v17.0.2.36 through v17.0.3, and the web shell was described as “weaponized,” with remote command execution and persistence mechanisms. Reporting also links the activity to INJ3CTOR3’s historical pattern of targeting VoIP platforms, including prior exploitation of CVE-2019-19006 (FreePBX) and CVE-2021-45461 (Elastix).
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5 events from the most recent confirmed update back to the earliest known activity.
On 2026-04-13, SANS Internet Storm Center reported active probing for the EncystPHP web shell via GET requests to /admin/modules/phones/ajax.php using the hard-coded md5 access string documented by Fortinet. The activity originated from 160.119.76.250 and also included FreePBX exploit attempts downloading a payload from 45.95.147.178, with warning that some payloads add multiple backdoor accounts on compromised systems.
On 2026-01-28, FortiGuard Labs published research on the high-severity campaign, detailing exploitation of CVE-2025-64328, the EncystPHP web shell, and associated infrastructure and detections. The report attributed the activity to patterns associated with the INJ3CTOR3 threat actor, previously linked to attacks on VoIP infrastructure and earlier vulnerabilities.
During the campaign, EncystPHP set up cron-based re-download and reinstallation, placed redundant web shells under /var/www/html/, created a root-level local account named newfpbx with UID 0, added an SSH public key, and ensured SSH port 22 remained open. It also deleted logs, forged timestamps, removed the Endpoint Manager module, disabled error reporting, and deleted competing web shells to evade detection and maintain long-term access.
After exploitation, the attackers used droppers such as "c" and "k.php" from infrastructure including 45.234.176.202 (crm.razatelefonia.pro) to install a Base64-encoded PHP web shell dubbed EncystPHP. The malware masqueraded as legitimate FreePBX files such as ajax.php and enabled remote command execution and operator access through an "Ask Master" interface.
In early December 2025, attackers began exploiting the post-authentication command-injection flaw CVE-2025-64328 in the FreePBX Endpoint Manager administrative interface. The activity targeted vulnerable FreePBX versions including v17.0.2.36 through v17.0.3 to gain shell access on VoIP/PBX systems.
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Attackers have been exploiting **CVE-2025-64328**, a post-authentication command injection flaw in the *Sangoma FreePBX Endpoint Manager* (filestore component) to compromise internet-exposed FreePBX systems and deploy persistent web shells. The vulnerability affects FreePBX versions `17.0.2.36` and above prior to `17.0.3`, and can be abused by an authenticated user via the `testconnection -> check_ssh_connect()` function to execute commands and gain remote access as the `asterisk` user; the issue is fixed in **17.0.3**. Reporting indicates the activity began in **December 2025** and has left hundreds of systems persistently backdoored with web shells. The **Shadowserver Foundation** reported roughly **900** FreePBX instances still compromised, with the largest concentration in the **United States** (about **400**) and additional impacted systems across **Brazil, Canada, Germany, France, the UK, Italy, and the Netherlands**. Fortinet/FortiGuard Labs identified a PHP web shell dubbed **EncystPHP** associated with the campaign, which supports remote command execution, persistence, and additional web shell deployment; follow-on risk includes VoIP-focused abuse such as **outbound call fraud** and potential network pivoting from the PBX host. One source also states the vulnerability has been added to **CISA’s Known Exploited Vulnerabilities (KEV) Catalog**, reinforcing the need for rapid patching and incident response on exposed FreePBX deployments.
Jun 29, 2026
Reporting highlights two separate developments: growing criminal adoption of **Vshell**, a Go-based command-and-control framework originally promoted in Chinese-speaking offensive security communities as a lower-cost alternative to *Cobalt Strike*. Research cited in the reporting describes Vshell’s evolution from a basic RAT into a more capable post-compromise platform supporting Windows and Linux administration, traffic tunneling/relay, pivoting, and lateral movement; internet scanning also identified exposed Vshell management panels with large numbers of connected agents (e.g., a recovered panel showing **286 active clients**), indicating real-world operational use. Separately, the **Shadowserver Foundation** reported that **900+ Sangoma FreePBX** instances remain infected with web shells following exploitation of **CVE-2025-64328** (CVSS 8.6), a post-authentication command-injection flaw affecting FreePBX versions `>= 17.0.2.36` and fixed in `17.0.3`. The issue has been added to **CISA’s KEV** catalog amid active exploitation, and Fortinet linked exploitation beginning in December 2025 to the **INJ3CTOR3** cyber-fraud operation delivering an `EncystPHP` web shell; recommended mitigations include restricting access to the FreePBX Admin Control Panel (ACP) and updating affected components (including the *filestore* module).
Jun 29, 2026
Breakglass Intelligence reported a financially motivated campaign targeting internet-exposed **FreePBX**, **Elastix**, **Issabel**, and related **Asterisk**-based VoIP systems with malware disguised as `k.php`. The malware exploits the FreePBX `restapps` REST API for remote code execution, deploys the **VictamPbx** PHP webshell across multiple PBX web paths, steals administrator credentials, hijacks admin sessions, and enables outbound call origination to abuse victim SIP trunks for **International Revenue Share Fraud (IRSF)**. Researchers observed at least 17 closely related variants and linked repeated payload delivery to infrastructure centered on `45.234.176.202` in Salvador, Bahia, Brazil, alongside branding and backend services associated with **VictamPbx**, **emoadmin**, **emo**, and **Raza Telefonia**. The newest variant expanded beyond fraud enablement by aggressively securing exclusive access to compromised systems. Its Stage 2 payload established persistence through root-level accounts, SSH keys, cron jobs, and boot/login mechanisms, while also disabling the endpoint module, scrubbing Apache logs, timestomping files, and removing implants, accounts, cron entries, and webshells tied to at least seven rival VoIP threat actors, including **Juba VoIP**, **Nahda**, **Badr/b3d0r**, **nvd0rz**, **tchTowr**, and **yokyok**. Breakglass assessed the activity as a Brazilian or Brazilian-affiliated operation that has likely been active since at least 2023, with the latest samples showing a territorial fight among criminal groups for exclusive control of vulnerable PBX infrastructure.
Jun 29, 2026