Storage Security Technology

The storage security technology industry is currently in the development phase, and in this process more questions than answers have been uncovered. However, emerging storage security organizations are designing solutions to help secure storage networks from both unauthorized users and accidental configuration mistakes. Existing storage vendors are also extending their product features to include security solutions. The following sections discuss the following storage security technologies that are under development as well as those that have already been deployed:

• Inline encryption

• Encryption at rest

• Key-based authentication

• Two-factor application authentication

Inline Encryption

Currently, the T11 committee is working on an initiative to incorporate IP Security (IPSec) technology established in the IP industry into the storage industry with iSCSI and Fibre Channel Security (FCSec). T11 has established a framework that will use ESP (Encapsulating Security Payload) in Fibre Channel layer 2 to protect frame data. ESP within the Fibre Channel frame will be able to provide confidentiality between two end nodes, such as a switch and an HBA.

Additionally, ESP will be able to enhance frame security by providing authentication, integrity, and anti-replay protection for each frame. This will prevent common attacks at the frame/packet layer, such as session hijacking, spoofing, and Man-In-The-Middle (MITM) attacks (described later in the chapter). The adoption of FCSec technology into the storage community will allow for greater flexibility for a storage network. Specifically, the key goals for the FCSec architecture are as follows :

• Node-to-node authentication

• Node-to-switch authentication

• Switch-to-switch authentication

• Frame-level encryption

Node-to-node authentication will allow each entity to authenticate frames transmitted between two nodes. This allows for the integrity of each frame between the two nodes and ensures against spoofing or replay attacks in the fabric.

Node-to-switch authentication will be similar to node-to-node authentication in that it ensures integrity in each frame. Additionally, node-to-switch authentication will allow switch management tools to contain added strength in their allocation mechanisms (for example, zone allocation).

Switch-to-switch authentication will allow each switch to ensure the integrity of data and management, such as Simple Name Server (SNS) information, to be protected against transport layer attacks. In addition, switch-to-switch authentication will reduce the possibility of a rogue switch gaining instant control of the entire fabric.

In addition to the authentication capabilities of FCSec at the frame level, confidentiality can be provided by using encryption of each frame as it exchanges data between two entities, including both node and switch entities.

Encryption at Rest

The encryption of data at rest uses a different approach than inline encryption. Standards committees are developing technologies such as FCSec to protect data and authentication for inline encryption. Encryption of data at rest is being addressed by new storage vendors and new storage products.

Data at rest is one of the most commonly overlooked risk areas in storage security. While most security efforts focus on protocols and architecture, the security of data at rest tends to be incorrectly assumed as secure. Data on disk is often considered secure because it is kept deep inside the storage network, with multiple storage devices restricting access. However, these types of security assumptions expose the data both to accidental actions and unauthorized activity.

Several new organizations are designing products to encrypt the data before it reaches the disk. At that level of encryption, if the storage node is compromised, the attacker will not have readable access to any of the data residing on the disk. In the event of a configuration error, the data on the disk may not be fully exposed due to the encrypted format of the data.

Various storage devices protect the data at rest in different ways, but all of them try to accomplish the same goal of protection. The encryption solutions that encrypt data on disk protect against possible configuration errors or mistakes commonly found in storage networks. Configuration errors are the most common problems identified in storage networks today. If controls are not in place to mitigate possible configuration issues, the ability to compromise data in the storage network might be larger than expected. Additionally, since storage networks are complicated by nature, the likelihood of a configuration error incorrectly exposing the SAN (Storage Area Network) is higher than for many other types of networks.

Figures 25-2 and 25-3 demonstrate two scenarios of configuration errors that might lead to the compromise of data. Figure 25-2 shows how configuration errors can occur at the storage switch. Figure 25-3 shows how an encryption device can protect against storage configuration errors.

Figure 25-2: Configuration errors at the storage switch

Figure 25-3: Encryption protects against storage configuration errors.

Key-Based Authentication

Fibre Channel-Generic Services-3 (FC-GS-3) is another technology that T11 standards organizations have developed. Key server technology is discussed in FC-GS-3 to enable key-based authentication, which supports the best practice of two-factor authentication in storage devices, such as switches, appliances, and clients . Unlike the FCSec project, the FC-GS-3 project is not solely a project about security. FC-GS-3 includes specifications dealing with management, directory service, time service, alias service, and other services. However, we will be referring to FC-GS-3 only in terms of the key server technology that it addresses.

The Key Distribution Service discussed in FC-GS-3 will provide a method for secure distribution of public and private keys in a storage network used for authentication, similar to a KDC (Kerberos Distribution Center) in IP networks. The security key server in the storage network would use a level of encryption to protect the keys and underlying protocols for verification purposes. By using a key server, data would be signed, providing a secure means of authenticating the original node as well as verifying the data was not modified during transit. This method of using a key server is often referred to as CT ( Common Transport ) authentication .

CT authentication is the process of authenticating requests between a client and a server. The CT authentication mechanism creates a hash based on an algorithm and secret key to represent the message signature associated with the sender. The hash is transferred as an extended preamble to the receiver. Upon receiving the hash, the receiver computes the hash before authenticating it, using the same algorithm and secret key, to make sure the hashes match.

The key server in the storage network would contain a copy of each nodes unique distribution key. The key server would then authorize the security connections between two nodes and would generate a key to use for authentication. This authentication key is then used by one node to authenticate to the other node. The single point of failure in the specification is the key server. If the key server does not contain the proper amount of security, the authentication model that the key server supports cannot be considered secure. Figure 25-4 shows an example of an authentication procedure using FC-GS-3.

Figure 25-4: Key distribution service

A practical example of FC-GS-3 would be the authentication of a World Wide Name (WWN) of an HBA in a storage network. In the Fibre Channel SAN Security section of this chapter, the security problems of WWN are discussed. It would not be best practice to use a WWN as the sole entity for authentication. The process of using FS-GS-3 to identify HBAs uniquely would allow the use of WWN without concerns of spoofing or replay attacks being performed successfully. Since WWNs are not reliable as a secure means of host identification, using a key server will minimize the risk of spoofing or session hijacking and allow the use of WWN with an acceptable level of integrity in the authentication process.

Currently, many switch vendors, such as Brocade and McData, are using a hybrid of the FC-GS-3 specification by using switch-to-switch key authentication. In this approach, each switch contains a unique key to authenticate to another switch. Instead of using a third key server device, the two nodes are directly authenticated to each other using their own keys. While this approach may not be as secure as having a key server, it does prevent a variety of attacks, primarily the ability for a rogue switch to take control of a given fabric, its simple name server, and its zoning architecture.

Two-Factor Application Authentication

Two-factor authentication for key applications, such as storage management applications, is becoming a significant requirement for protecting storage networks. The fact that storage management applications can subvert the majority of other security controls within the storage environment makes the management applications a significant target for most attackers .

Currently, many management applications rely on a username/password combination for authentication. As best practice, a single username and password should not be the only security entity protecting a storage network. For example, an unauthorized user should not be able to plug into a network with his favorite backup program and successfully manage storage agents because he was able to guess the username/password combination or spoof an IP address.

Requiring more than a username and password or an IP address for authentication is possible. To address this issue, certain vendors have included a second level of authentication within the management application itself. These management applications use public and private keys for authentication with authenticated Secure Sockets Layer (SSL) or Kerberos technology to mitigate some of the exposures described so far. Therefore, if an unauthorized user has plugged into the network and successfully guessed a password or spoofed a management IP address, the attackers rogue backup software would not be able to gain access to the storage agents since a second level of authentication is required. The second level of authentication required from a client application to the server application and/or agents could use tokens, digital certificates, Kerberos tickets, public keys, or other forms of security. This type of application design may utilize usernames/passwords and IP addresses, but it also utilizes credentials implicit in the client application to authenticate to the server and/or storage agents.

Note 

Tokens, digital certificates, Kerberos tickets, and public keys can be used for authentication. All these security entities can be delivered digitally to authenticate a sending node to a receiving node, such as storage management software, in place of or in addition to username/ password authentication.