CVE-2026-28776: IDC SFX Series Auth Bypass Vulnerability

CVE-2026-28776 Overview

International Datacasting Corporation (IDC) SFX Series SuperFlex SatelliteReceiver contains hardcoded credentials for the monitor account. A remote unauthenticated attacker can use these trivial, undocumented credentials to access the system via SSH. While initially dropped into a restricted shell, the attacker can trivially break out to achieve standard shell functionality.

Critical Impact

Remote unauthenticated attackers can leverage hardcoded credentials to gain SSH access to vulnerable satellite receiver devices, with the ability to escape the restricted shell and achieve full system access.

Affected Products

• International Datacasting Corporation (IDC) SFX Series SuperFlex SatelliteReceiver

Discovery Timeline

• 2026-03-04 - CVE CVE-2026-28776 published to NVD
• 2026-03-05 - Last updated in NVD database

Technical Details for CVE-2026-28776

Vulnerability Analysis

This vulnerability falls under CWE-798 (Use of Hard-coded Credentials), a critical security flaw where authentication credentials are embedded directly into the device firmware or software. The IDC SFX Series SuperFlex SatelliteReceiver ships with an undocumented monitor account that contains trivial, easily guessable hardcoded credentials.

The attack surface is significant because the vulnerability is exploitable remotely over the network via SSH, requiring no prior authentication or user interaction. Once an attacker connects to the device using these hardcoded credentials, they initially land in a restricted shell environment. However, this restriction provides only minimal protection, as the shell escape techniques required to achieve standard shell functionality are trivial to execute.

The combination of network-accessible SSH, hardcoded credentials, and a bypassable restricted shell creates a pathway for complete device compromise. Satellite receiver infrastructure is often deployed in critical broadcast and communications environments, making this vulnerability particularly concerning for organizations relying on these devices.

Root Cause

The root cause of this vulnerability is the inclusion of hardcoded credentials for the monitor account directly within the device's firmware or configuration. This represents a fundamental security design flaw where developers included a backdoor or maintenance account with static credentials that cannot be changed by end users. Additionally, the restricted shell implementation lacks sufficient robustness to prevent escape techniques, compounding the security impact.

Attack Vector

The attack is network-based and requires no authentication, user interaction, or special conditions. An attacker can:

1. Identify vulnerable IDC SFX Series SuperFlex SatelliteReceiver devices exposed to the network
2. Connect to the device via SSH using the hardcoded monitor account credentials
3. Execute shell escape techniques to break out of the restricted shell
4. Achieve full shell access with the privileges of the monitor user

The vulnerability allows attackers to bypass authentication entirely using the known static credentials, and the subsequent restricted shell escape provides unauthorized access to system functionality.

Detection Methods for CVE-2026-28776

Indicators of Compromise

• Unexpected SSH connections to satellite receiver devices from unauthorized IP addresses
• Login attempts or successful authentications using the monitor account
• Evidence of shell escape commands or unusual command sequences in system logs
• Unauthorized processes or modifications to system configurations on affected devices

Detection Strategies

• Monitor SSH authentication logs for connections using the monitor username
• Implement network intrusion detection rules to flag SSH connections to known vulnerable device IP ranges
• Deploy honeypot accounts that mirror the hardcoded credential pattern to detect scanning activity
• Review audit logs for indicators of restricted shell escape attempts

Monitoring Recommendations

• Enable comprehensive logging on all network segments containing IDC SFX Series devices
• Configure SIEM alerts for authentication events involving the monitor account
• Establish baseline network behavior for satellite receiver infrastructure to identify anomalies
• Monitor for port scanning activity targeting SSH services on device management networks

How to Mitigate CVE-2026-28776

Immediate Actions Required

• Isolate affected IDC SFX Series SuperFlex SatelliteReceiver devices from untrusted network segments
• Implement network access controls to restrict SSH access to authorized management systems only
• Block SSH access from the internet and any untrusted networks to affected devices
• Deploy firewall rules to limit connectivity to satellite receiver management interfaces

Patch Information

Consult the vendor for firmware updates that address the hardcoded credential vulnerability. For detailed technical analysis and additional information, refer to the Abdul MHS Blog Vulnerability Analysis.

Workarounds

• Implement strict network segmentation to isolate vulnerable devices from general network traffic
• Use VPN or jump hosts to access device management interfaces, limiting direct SSH exposure
• Configure additional authentication layers (such as port knocking) if supported by network infrastructure
• Monitor and alert on all SSH connection attempts to affected devices until a vendor patch is available

# Example firewall rule to restrict SSH access to management subnet only
iptables -A INPUT -p tcp --dport 22 -s 10.10.10.0/24 -j ACCEPT
iptables -A INPUT -p tcp --dport 22 -j DROP