AudioCodes Fax/IVR Appliance <= 2.6.23 Unauthenticated Backup Upload RCE via ajaxBackupUploadFile.php

Vulnerability Description

AudioCodes Fax Server and Auto-Attendant IVR appliances versions up to and including 2.6.23 expose an unauthenticated backup upload endpoint at AudioCodes_files/ajaxBackupUploadFile.php in the F2MAdmin web interface. The script derives a backup folder path from application configuration, creates the directory if it does not exist, and then moves an uploaded file to that location using the attacker-controlled filename, without any authentication, authorization, or file-type validation. On default Windows deployments where the backup directory resolves to the system drive, a remote attacker can upload web server or interpreter configuration files that cause a log file or other server-controlled resource to be treated as executable code. This allows subsequent HTTP requests to trigger arbitrary command execution under the web server account, which runs as NT AUTHORITY\\SYSTEM.

References

• https://www.audiocodes.com/media/g1in2u2o/0548-product-notice-end-of-service-for-audiocodes-auto-attendant-ivr-solution.pdf
• https://pierrekim.github.io/blog/2025-11-20-audiocodes-fax-ivr-8-vulnerabilities.html
• https://pierrekim.github.io/advisories/2025-audiocodes-fax-ivr.txt
• https://www.vulncheck.com/advisories/audiocodes-fax-ivr-appliance-unauthenticated-backup-upload-rce-via-ajaxbackupuploadfile