CVE-2026-28775 Overview
An unauthenticated Remote Code Execution (RCE) vulnerability exists in the SNMP service of International Datacasting Corporation (IDC) SFX Series SuperFlex Satellite Receiver. The deployment insecurely provisions the private SNMP community string with read/write access by default. Because the SNMP agent runs as root, an unauthenticated remote attacker can utilize NET-SNMP-EXTEND-MIB directives, abusing the fact that the system runs a vulnerable version of net-snmp pre 5.8, to execute arbitrary operating system commands with root privileges.
Critical Impact
This vulnerability allows unauthenticated remote attackers to execute arbitrary commands with root privileges on affected satellite receiver devices, potentially leading to complete system compromise, service disruption, and lateral movement within broadcast infrastructure networks.
Affected Products
- International Datacasting Corporation (IDC) SFX Series SuperFlex Satellite Receiver
- Devices running net-snmp versions prior to 5.8
- Systems with default private SNMP community string configured
Discovery Timeline
- 2026-03-04 - CVE-2026-28775 published to NVD
- 2026-03-05 - Last updated in NVD database
Technical Details for CVE-2026-28775
Vulnerability Analysis
This vulnerability stems from insecure default configuration (CWE-1188) in the IDC SFX Series SuperFlex Satellite Receiver's SNMP service implementation. The root cause involves two compounding security weaknesses: the use of a predictable default SNMP community string and the execution of the SNMP agent with root privileges.
The SNMP service on affected devices is configured out-of-the-box with the private community string providing read/write access. This well-known default credential allows any network-accessible attacker to authenticate to the SNMP service without requiring any prior knowledge or credentials specific to the target device.
Compounding this misconfiguration, the SNMP agent executes with root privileges, and the underlying net-snmp implementation (versions prior to 5.8) supports the NET-SNMP-EXTEND-MIB functionality. This MIB extension allows authorized users to define and execute arbitrary shell commands on the host system. When combined with root-level execution context, an attacker can leverage SNMP write access to inject malicious commands that execute with full system privileges.
Root Cause
The vulnerability results from insecure default configuration (CWE-1188) where the SNMP service is deployed with a predictable community string and elevated privileges. The combination of a well-known default credential (private) with read/write access, coupled with the SNMP daemon running as root on a vulnerable net-snmp version, creates a direct path to unauthenticated remote code execution. The NET-SNMP-EXTEND-MIB feature in net-snmp versions prior to 5.8 permits extending the agent with arbitrary scripts, which becomes a critical attack vector when combined with insecure defaults.
Attack Vector
The attack is network-based and requires no authentication or user interaction. An attacker with network access to the SNMP service (typically UDP port 161) can exploit this vulnerability by:
- Connecting to the target device's SNMP service using the default private community string
- Utilizing SNMP SET operations to configure NET-SNMP-EXTEND-MIB directives
- Defining arbitrary shell commands to be executed by the SNMP agent
- Triggering command execution through subsequent SNMP operations
The attack leverages the nsExtendObjects OID tree to register malicious commands. Once registered, these commands execute with the privileges of the SNMP daemon process, which in this case runs as root. This provides the attacker with complete control over the affected device.
For detailed technical analysis and proof-of-concept information, see the Abdul MHS Blog Vulnerabilities Analysis.
Detection Methods for CVE-2026-28775
Indicators of Compromise
- Unexpected SNMP SET requests targeting nsExtendObjects OID trees from external or unauthorized IP addresses
- Presence of new entries in SNMP extend configuration that were not administratively created
- Unusual process spawning from the snmpd process, particularly shell interpreters like /bin/sh or /bin/bash
- Network connections or reverse shells originating from satellite receiver devices
Detection Strategies
- Monitor SNMP traffic on UDP port 161 for SET operations, particularly those targeting OIDs related to NET-SNMP-EXTEND-MIB (.1.3.6.1.4.1.8072.1.3)
- Implement network segmentation and firewall rules to restrict SNMP access to authorized management stations only
- Deploy network intrusion detection rules to alert on SNMP community string brute forcing or use of common default strings like private, public, or community
- Monitor process creation events on satellite receiver devices for suspicious child processes of snmpd
Monitoring Recommendations
- Enable SNMP authentication logging and monitor for successful authentications using the private community string from unexpected sources
- Implement continuous vulnerability scanning to identify devices with default SNMP configurations
- Monitor for lateral movement attempts originating from compromised satellite receiver infrastructure
- Configure SIEM alerting for SNMP traffic anomalies including unusual payload sizes or high-frequency SET operations
How to Mitigate CVE-2026-28775
Immediate Actions Required
- Change the default SNMP community strings immediately on all affected devices, using complex, unique strings
- Restrict network access to the SNMP service using firewall rules to allow only authorized management stations
- If SNMP is not required for operations, disable the service entirely on affected devices
- Upgrade net-snmp to version 5.8 or later where NET-SNMP-EXTEND-MIB security controls have been improved
- Audit devices for signs of compromise before implementing remediation
Patch Information
Contact International Datacasting Corporation for firmware updates that address the insecure default configuration. The vendor should be consulted for specific patch availability and upgrade procedures for the SFX Series SuperFlex Satellite Receiver product line. Additional technical details are available in the Abdul MHS Blog Vulnerabilities Analysis.
Workarounds
- Implement SNMPv3 with authentication and encryption if supported by the device, eliminating reliance on community strings
- Apply network segmentation to isolate satellite receiver infrastructure from general network access
- Deploy access control lists (ACLs) on network devices to restrict SNMP traffic to specific authorized management IP addresses
- Configure the SNMP agent to run with reduced privileges if the device firmware supports this configuration
- Disable the NET-SNMP-EXTEND-MIB functionality if not operationally required
# Example network ACL to restrict SNMP access (adjust for your environment)
# Restrict SNMP UDP 161 access to management subnet only
iptables -A INPUT -p udp --dport 161 -s 10.0.0.0/24 -j ACCEPT
iptables -A INPUT -p udp --dport 161 -j DROP
# Verify SNMP community string configuration
snmpwalk -v2c -c private <target_ip> system
# If the above command succeeds, the default community string is still in use
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
