CVE-2026-29125 Overview
IDC SFX2100 Satellite Receivers contain an insecure file permissions vulnerability where the /etc/resolv.conf file is configured to be world-writable by any local user. This misconfiguration allows any authenticated local user to modify the DNS resolver configuration, enabling DNS tampering attacks that can redirect network communications to attacker-controlled servers, facilitate man-in-the-middle attacks, and cause denial of service conditions.
Critical Impact
Local attackers can hijack DNS resolution to redirect network traffic, intercept sensitive data, and disrupt device connectivity by tampering with world-writable resolver configuration.
Affected Products
- IDC SFX2100 Satellite Receivers
Discovery Timeline
- 2026-03-05 - CVE CVE-2026-29125 published to NVD
- 2026-03-05 - Last updated in NVD database
Technical Details for CVE-2026-29125
Vulnerability Analysis
This vulnerability is classified under CWE-732 (Incorrect Permission Assignment for Critical Resource). The /etc/resolv.conf file is a critical system configuration file that controls which DNS servers the device uses for hostname resolution. On properly configured systems, this file should only be writable by the root user or system processes.
In the affected IDC SFX2100 satellite receivers, the file permissions are set to allow any local user to modify the contents. This creates a significant security gap where an attacker with minimal local access can alter DNS resolution behavior for the entire device.
Root Cause
The root cause of this vulnerability is improper file permission assignment during device configuration or firmware installation. The /etc/resolv.conf file was configured with world-writable permissions (likely mode 666 or 777) instead of the secure default (typically mode 644 with root ownership). This oversight allows unprivileged local users to modify DNS server settings, which should be a privileged operation.
Attack Vector
This vulnerability requires local access to exploit. An attacker with any level of local user access to the IDC SFX2100 device can modify the /etc/resolv.conf file to point to malicious DNS servers under their control. Once the DNS resolver is hijacked, the attacker can:
- Redirect legitimate domain queries to attacker-controlled IP addresses
- Perform man-in-the-middle attacks by proxying connections through malicious infrastructure
- Cause denial of service by pointing DNS to non-responsive servers
- Phish credentials by redirecting authentication endpoints to spoofed pages
- Intercept firmware updates if the device resolves update servers via DNS
The attack can be executed with a simple file write operation. An attacker would modify the nameserver entries in /etc/resolv.conf to point to their own DNS server, which would then respond with malicious records for any queries made by the device.
Detection Methods for CVE-2026-29125
Indicators of Compromise
- Unauthorized modifications to /etc/resolv.conf file on affected satellite receivers
- DNS server entries pointing to unexpected or suspicious IP addresses
- Changes to file modification timestamps on /etc/resolv.conf not associated with authorized maintenance
- Unexpected network connections to unknown DNS servers
Detection Strategies
- Monitor file integrity of /etc/resolv.conf using file integrity monitoring solutions
- Audit system logs for file access and modification events targeting resolver configuration
- Compare DNS server configurations against known-good baseline configurations
- Implement network monitoring to detect DNS queries to unauthorized resolvers
Monitoring Recommendations
- Deploy endpoint monitoring to track changes to critical configuration files
- Configure alerting on any modifications to /etc/resolv.conf outside of scheduled maintenance windows
- Monitor outbound DNS traffic (port 53 UDP/TCP) for connections to non-sanctioned DNS servers
- Implement SentinelOne Singularity for real-time file integrity monitoring and threat detection on embedded devices
How to Mitigate CVE-2026-29125
Immediate Actions Required
- Review and correct file permissions on /etc/resolv.conf to restrict write access to root only
- Verify current DNS server configuration for any unauthorized modifications
- Restrict local user access to the device to trusted administrators only
- Implement network-level DNS filtering to prevent connections to unauthorized resolvers
Patch Information
No vendor patch information is currently available. For technical details and updates, refer to the Abdulmhs Blog Vulnerability Post which documents this vulnerability.
Workarounds
- Manually correct file permissions by setting /etc/resolv.conf to mode 644 with root ownership
- Implement a watchdog script to periodically verify and restore correct permissions
- Use network-level controls to restrict DNS traffic to authorized servers only
- Consider implementing immutable file attributes where supported by the filesystem
# Corrective configuration example
# Fix file permissions on resolv.conf
chmod 644 /etc/resolv.conf
chown root:root /etc/resolv.conf
# Optionally set immutable attribute to prevent modification
chattr +i /etc/resolv.conf
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
