While many organizations exchange files by uploading them to a server in the DMZ, staging files in the publicly accessible DMZ makes them vulnerable to a variety of dangerous exploits.
Exchanging files with customers and trading partners is commonplace in today's global economy, but keeping that data secure remains a difficult challenge as does staying in compliance with the various regulations governing data security, including PCI DSS, HIPAA, SOX, GBLA, and more.
A common approach for protecting internal/private networks is for companies to install file-sharing services (e.g. FTP/S, SFTP, HTTP/S servers) in a public zone for trading partners to access. When those servers and files leave the safety of the private network, however, companies risk the exposure of those services and data to outside attacks.
This white paper addresses the following questions:
1. Why is it dangerous for companies to store FTP servers and other file services in the DMZ?
2. How does incorporating a gateway into the file transfer process provide better protection for sensitive data?
3. How do gateways keep an organization's private network insulated from external reach?
DMZ for Staging Files
DMZ stands for demilitarized zone, and it's the neutral network that resides between the Internet and your company's private network. The DMZ is provisioned with a front-end firewall that limits inbound Internet traffic to certain systems within its zone. On the back end, another firewall is placed to prevent unauthorized access from the DMZ into the private network.
An organization's DMZ typically contains Web servers, FTP/S, SFTP, and HTTP/S servers, as well as other services it wants to make available to its customers and trading partners. To serve their purpose, these services need access to the data files that will be shared with partners.
The DMZ serves as a staging area between an organization's private network and the Internet. In order to share a document with a trading partner, an internal program or employee first copies the file from the private network onto a server in the DMZ. The partner then downloads the file from that server using an approved protocol like FTP/S, SFTP, or HTTP/S.
When trading partners need to share documents with the organization, they upload the files to a server in the DMZ. Later, an internal program or employee scans for the files on that server and pulls them into the private network.
Dangers in the DMZ
While many organizations exchange files using this process, staging files in the publicly accessible DMZ makes them vulnerable to a variety of dangerous exploits:
- If attackers gain entry to a file server in the DMZ, they may be able to access sensitive trading partner files that were placed there. These files could be downloaded and their contents could be exposed by the attacker. Even encrypted files may be at risk to sophisticated attackers if the keys or passwords can be compromised. This concern is causing an increasing number of compliance auditors to prohibit data storage in the DMZ, encrypted or not.
- When the file-sharing services are in the DMZ, then any user credentials, certificates, etc. needed for authentication are likely maintained there too, which makes them more vulnerable to attacks.
- Also at risk is the file-sharing software itself, especially if it can be administered from within the DMZ. For example, an attacker could create a "back door" user account into an SUP server through its admin console. This seemingly "legitimate" user account could then be used by the attacker to gather sensitive data files over an extended period of time. Audit logs for the software could also be manipulated if they are stored in the DMZ, erasing the attacker's trail.