This threat involves scanning activity detected in network logs where attackers attempt to authenticate to FTP servers using usernames related to 3CX, a popular business phone system software vendor. The specific username "FTP_3cx" is not a documented default user, and 3CX itself does not run an FTP server but supports backing up its configuration files to an external FTP server. The scans likely target these external FTP servers configured by administrators to store 3CX backups. Attackers use a range of usernames such as "3cx", "3CXBackup", "backup3cx", and "FTP_3cx" combined with weak or guessable passwords like "3CXBackup" and "telecom" to gain unauthorized FTP access. Since FTP credentials often overlap with system user credentials, successful FTP compromise could allow attackers to access telnet or SSH services, escalating their foothold on the system. The backup data stored on these FTP servers may contain sensitive configuration details that could facilitate further compromise of the 3CX system or the broader network. The threat does not exploit a vulnerability in 3CX software itself but exploits poor security practices around backup storage and credential management. No public exploits or CVEs are associated with this activity, and the threat is currently observed as scanning and credential guessing attempts without confirmed breaches. The use of FTP, an unencrypted protocol, further exacerbates the risk by exposing credentials and data in transit. This threat underscores the importance of securing backup mechanisms, using strong, unique credentials, and avoiding legacy protocols like FTP for sensitive data transfers.

For European organizations using 3CX phone systems, this threat could lead to unauthorized access to backup FTP servers if weak or default credentials are used. Compromise of these backups may expose sensitive configuration data, enabling attackers to disrupt telephony services, intercept communications, or pivot to other internal systems. Given that FTP credentials may overlap with system login credentials, attackers could gain broader network access via telnet or SSH, increasing the risk of data breaches or service outages. The impact is particularly significant for organizations relying heavily on 3CX for business communications, such as call centers, enterprises, and public sector bodies. Additionally, the use of unencrypted FTP increases the risk of credential interception on the network. While no active exploitation is reported, the scanning activity indicates reconnaissance that could precede targeted attacks. This threat could disrupt business continuity, compromise confidentiality of communications, and damage organizational reputation. European entities with lax backup security or legacy FTP setups are at higher risk.

European organizations should immediately audit their 3CX backup configurations to identify any FTP servers used for storing backups. Replace FTP with secure alternatives such as SFTP or FTPS to encrypt data in transit and prevent credential interception. Enforce strong, unique passwords for all backup-related user accounts and disable any default or unused accounts. Implement multi-factor authentication where possible for access to backup servers. Restrict FTP server access via network segmentation and firewall rules to only trusted hosts. Regularly monitor logs for unusual authentication attempts or scanning activity targeting 3CX-related usernames. Consider encrypting backup files themselves to protect sensitive configuration data even if the storage server is compromised. Educate administrators on the risks of using legacy protocols and the importance of secure backup practices. Conduct periodic penetration testing and vulnerability assessments focused on backup infrastructure. Finally, keep 3CX software and related systems updated and follow vendor security guidance to minimize exposure.