CVE-2023-7008: Critical Vulnerability Found in systemd-resolved Allowing Unsigned DNSSEC Records and Potential for DNS Manipulation

A critical vulnerability (CVE-2023-7008) has recently been discovered in systemd-resolved, which is a system service provided by the systemd software suite to manage network name resolution. This vulnerability could allow an attacker to manipulate DNS records, which are crucial for identifying devices on the internet and directing the flow of data and communications. The exploit occurs when systemd-resolved accepts and processes DNSSEC-signed domains without verifying their signatures, potentially leading to a man-in-the-middle attack and other serious security risks.

Exploit Details

Systemd-resolved supports DNSSEC (Domain Name System Security Extensions), which is a security measure intended to add an additional layer of trust and verification for DNS records. DNSSEC does this by signing DNS records with digital signatures to ensure the integrity and authenticity of the information.

However, this vulnerability could allow an attacker to forge or manipulate DNS records without the person or device using systemd-resolved ever suspecting that the records have been tampered with. Specifically, systemd-resolved may accept records that have not been signed by the expected DNSSEC mechanisms, leaving the system vulnerable.

The vulnerability lies in how systemd-resolved processes DNSSEC records from upstream DNS resolvers. In certain cases, it may not actually verify that the resolver's signatures are valid, opening the door for potential spoofing and manipulation of DNS records.

Below is a code snippet demonstrating this vulnerability, which has been identified as CVE-2023-7008

// vulnerability_detected() is a simplified example
// of faulty logic in processing DNSSEC records
bool vulnerability_detected()
{
   dnssec_signatures = get_dnssec_signatures(domain);
   if (dnssec_signatures == NULL) 
   {
      // The domain is not DNSSEC-signed.
      return false;
   }

   // If there are any records, but their
   // signatures are not valid, return true.
   if (!verify_dnssec_signatures(dnssec_signatures)) 
   {
      return true;
   }

   return false;
}

bool check_vulnerability()
{
   if (vulnerability_detected()) 
   {
      printf("Vulnerability CVE-2023-7008 detected!\n");
      return true;
   }

   printf("System is not affected by CVE-2023-7008.\n");
   return false;
}

The original reference for this vulnerability can be found here: CVE-2023-7008 References

Mitigation

To avoid falling prey to this vulnerability, users should ensure they are using the most recent version of systemd that has the necessary patches to address this flaw. If the vulnerability is detected, it is imperative to take the necessary steps to mitigate the risk of DNS manipulation or spoofing.

Conclusion

The discovery of this vulnerability is a reminder that even widely-used and trusted systems like systemd can fall prey to serious security vulnerabilities. As always, it is crucial for developers, administrators, and users to stay up-to-date on the latest security reports, update their systems, and verify the trustworthiness of the DNS records they rely on for communication and networking.

Timeline

Published on: 12/23/2023 13:15:07 UTC
Last modified on: 01/27/2024 03:15:07 UTC