A signed agreement among business partners helps, but guarantees nothing. Incidentally, it can also discourage disclosure. Persuading them to implement better information security practices (i.e., spend more) can be fruitless.

Despite the difficulties, we often need an agreement signed to help facilitate avoiding the following risks posed by our business partner endpoints:

• Infect our mission critical servers (Risk 1)
• Leak data via malware (Risk 2)
• Leak data via removable media (Risk 3)
• Leak data via high-risk endpoint hard drives (Risk 4)

Limit server access to partner endpoints of acceptable risk.
Limit access to machines not just people. Limiting access based on both identity and health requires network access control (NAC) technology, such as Microsoft Network Access Protection (NAP).

• Try to limit access to machines that process as little data, documents, or media from the outside world as practical (Risk 2). This also means denying access to endpoints running p2p and other software.
• Ensure that anti-virus and anti-spyware software are running, up-to-date, and frequently conduct full scans (Risk 2)
• Try to require other anti-malware tools because signature-based anti-malware products are becoming more ineffective every week (Risk 2).
• Deny access to endpoints with promiscuous removable media settings (Risk 3)

Data stored on partner endpoints must be encrypted.
Fixed and mobile PCs can be physically compromised. Limit server access to endpoints with full disk encryption (Risk 4). Second, also limit access to machines that require two factor authentications to utilize the endpoint (Risk 4). If your partner’s disk encryption solution can ensure that write operations to removable media are encrypted, then you might ease up on removable media settings requirements (Risk 3).

Consider limiting partner server access to thin client machines.
One can be very confident that no malware is operating within a freshly rebooted thin client machine (Risk 1). This can also be the most effective, albeit Draconian, risk mitigation to data leaks (Risk 2, 3, and 4). BTW, you could also have them access mirrors of your mission critical servers instead (Risk 1).

Rene would have had to work a lot harder at his USB thumb drive based theft if Countrywide had deployed some technology to keep unknown machines off its LAN. The most basic approach limits admission to machines that are part of their Windows domains.

Today’s enterprise, however, requires access to networked resources for contractors and others with their own PCs. The Countrywide administrators could have created non-domain credentials for these guest workers. The individual server applications would refer to any one or more of a variety of tools in the typical enterprise to handle these authentications between the individual server applications and the endpoints/end-users.

This provides nice but not great compartmentalization. It does not prevent machines from sending malicious data to the application servers or other client machines. It also does not prevent eavesdropping.

Administrators could implement a more robust form of compartmentalization involving 802.1x via their Ethernet switches. This enables the Ethernet switches to regulate what part of the network a particular PC may utilize based on the identity of the end-user or machine.

Unfortunately, 802.1x can only limit network admission based on who the machine or end-user is, not what is the apparent risk of that machine being on the network. If a machine has absolutely no preventative measures in place to mitigate important security risks, then it should not be admitted.

So, Countrywide had employed technology on all employee PCs to disable USB storage devices. Clearly they were concerned with data leaks. So, this implies that they would not want machines with enabled USB storage capabilities onto their LAN.

Network admission control (NAC) is an excellent technology for satisfying such a risk mitigation policy. I recommend Microsoft NAP because it scales better than alternatives, requires less infrastructure upgrades (if any) than alternatives, and it’s extremely extensible.

To those charged with reducing the risks of data leaks, you require two hammers. One resides on each PC to disable or regulate write-operations to USB thumb drives. The second hammer, NAP, prevents endpoints without the first hammer from accessing networked resources.