Discuss the risks to the protected internal network as a result of a DMZ

A Demilitarized Zone (DMZ) aims to shield the internal network by hosting public-facing services in an isolated segment. However, risks to the protected internal network persist if the DMZ itself is compromised.

• Lateral Movement: If an attacker compromises a server in the DMZ, they can use it as a pivot point. The compromised DMZ server may then exploit vulnerabilities or misconfigurations in firewall rules that allow communication with the internal network. This enables movement from the DMZ deeper into the protected internal network.
• Misconfigured Firewall Rules: Improperly configured firewall rules between the DMZ and the internal network can create unintended pathways. Overly permissive rules can allow unapproved traffic, forming a direct attack vector from a compromised DMZ host to sensitive internal resources.
• Trust Relationships Exploitation: Internal systems may have trust relationships or specific allowed connections to DMZ servers for operational needs. An example is an internal database server providing data to a public-facing web server in the DMZ. A compromised DMZ server can exploit these necessary connections to access or manipulate internal data or systems.
• Zero-Day Vulnerabilities: Even with strong security, a zero-day exploit against a DMZ-hosted application or operating system can grant an attacker a foothold. Once inside the DMZ, the attacker can search for further vulnerabilities to bypass the inner firewall and access the internal network.