Ask The Security Experts: Public Facing Workstations

This time around, we have a question from a reader named John: “I work in a small financial institution and we have problems with physical access to our computers. Many of our workstations sit in semi-public areas and could easily be attacked with USB devices or physical access when a teller or customer service person leaves the customers alone with the machine at a desk or cubicle. What advice do the experts have to help counter these types of attacks?”

Bill Hagestad started the conversation:

Recommended Points for mitigating this digital & physical vulnerability;

1) Remove workstations from semi-public areas; 2) Deploy & install single – purpose Internet workstations at no more than 2 public locations with VERY limited access to financial institution records only after 3 factor authentication has been authorized by credentialed users only; 3) Set time limites on inactive sessions on all banking terminals to logoff after physical proximity to machine exceeds 15 seconds; 4) Enforce 32 random, alpha-numeric character password changes to all critical financial institutional systems weekly; and, 5) Implement and /or continue aggressive financial institution information assurance education program with goal of 100% employee participation; review/update monthly and, 6) Mandate information security and awareness program participation from financial institution leadership throughout all employees and ranks within the organization.

John Davis expanded: I know how difficult this is for financial institutions. Your customer service representatives need computers in their cubicles in order to provide service to your customers, while at the same time those same computers are a main point of physical vulnerabilitiy. Easy steps can be taken, though, to harden these work stations.

First, workstation users should be allotted local administration rights on their systems only when a business need is present. So, CSR workstations should have their USB and DVD ports disabled. Furthermore, their is no need for them to have the ability to upload or download software. In addition, workstations in publicly accessible areas must be turned off each and every time they are unattended. Perhaps you could implement a system similar to the cut off device used on treadmills or at casinos: CSRs would have to clip a device from their clothing to the workstation before it will work. You could accompany this with biometric access for quick and easy access for the users.

Jim Klun added:

From my experience, and assuming the worst case of Windows systems configured as normal workstations with end-users having admin level access, some immediate things I would do:

1. Disable all removable media access at the hardware ( i.e. BIOS) level. At minimum: disable ability to boot from such sources. or: remove all DVD and CDROM drives and physically disable USB ports. (e.g. glue) 2. Ensure all workstations log activity and ensure that the logs are directed to a central log repository and reviewed. Example: 3. Ensure surveillance cameras cover workstation areas. 4. Aggressive screen-lock settings 5. Removal of admin access for all but limited support staff if at all possible. 6. Consider Usage of security cabinets for workstations: Example: 7. Network Access Control to limit what devices are allowed on the local network. That unattended RJ45 jack or poorly secured wireless environment is as much a threat as that USB port or CDROM. Bluetooth setting should also be reviewed. 8. Ensure all sensitive information traveling over the local LAN is encrypted. 9. Use a firmware password ( e.g drivelock or a BIOS power-on password) to limit who can boot the machine. 10. Monthly re-iteration of security policies – including need to lock workstations. In my experience such messages are best tied to real-world examples. It makes the risk real – not just an abstract “security guy” worry. For example, this event could be used to ensure employees are aware that an unlocked workstation could lead to the installation of malware:

I note that both JD and Bill talk about enhanced authentication – including the use of proximity devices. Using such devices ( mostly bluetooth ) to secure these workstations sounds like a great idea to me and may be the easiest and most effective solution. Once the financial institution walks away from the workstation – it’s locked and ideally will not boot. – open source Google “computer proximity lock” for a number of commercial alternatives.

Adam Hostetler closed the conversation with:

Everyone has really good suggestions so far. I am a fan of the simple phsyical solutions. I would put the workstations in locked cages. This would prevent any malicious people from inserting USB devices or CDs, or implanting sniffers between the keyboard and USB ports. Additionally, follow the other advice of disabling them through software, just to be sure.

Another solution may be to move to a thin client solution. It is possible to buy thin clients that have no USB ports or optical drives. This would also ensure that no sensitive information was on the workstation, in the event that it was stolen.

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