Security Auditors can be a clever lot, sometimes a bit too clever. You really need to have someone on staff looking over their shoulder throughout the entire audit, from planning through probing, and reporting. If you don't have someone on staff qualified to watch them, you need an independent consultant. A very sharp generalist would do, but someone experienced in security would be better. Basically you need a check and balance system in place, to keep stories like the following from happening to your organization. First the context. The auditors created a custom Trojan, planted it in amidst various other files on USB drives, and seeded them in parking lots and areas of the client's work area where they would likely be discovered by customers. Which, of course, they were. Here's what they say about the experience: Social Engineering, the USB Way
I had one of my guys write a Trojan that, when run, would collect passwords, logins and machine-specific information from the user’s computer, and then email the findings back to us. ... I immediately called my guy that wrote the Trojan and asked if anything was received at his end. Slowly but surely info was being mailed back to him. ... After about three days, we figured we had collected enough data. When I started to review our findings, I was amazed at the results. Of the 20 USB drives we planted, 15 were found by employees, and all had been plugged into company computers. The data we obtained helped us to compromise additional systems, and the best part of the whole scheme was its convenience. We never broke a sweat. Everything that needed to happen did, and in a way it was completely transparent to the users, the network, and credit union management.Yes, you read that right. Their custom trojan emailed the client's account names and passwords and other (presumably important) data out to the auditors' off-site email accounts. Now, unless these guys put rather a lot more effort into their custom trojan than they described, email is a plain text protocol. So, any fifteen year old kid with a summer job sitting on a router or an SMTP gateway at an ISP between the client and the auditor's email basket can read that email. Of course, it's possible the trojan was equipped with an X.509 certificate and encryption system, but it seems to me that if the auditors had thought of this, they would have mentioned it. It would have been a source of pride. For either forgetting to encrypt the data, or failing to mention it in their storytelling, they will undoubtedly be punished by the flood of email they are bound to get from every GSEC and CISSP certified security analyst on the planet. I don't want to be too critical, because they seem to have the best intentions, and their effort served to illustrate a point that clients often don't take seriously -- USB drives really can be dangerous, even if you don't inhale one. However, in their excitement to put the clever idea to the test, these auditors seem to have overlooked one important layer of the security cake and the important dictum, useful to all consultants, "first, do no harm." Of course, this isn't the most egregious error ever committed by an auditor. Far from it, in fact. I've personally seen Auditor's laptops spewing worm traffic on a client's network. Of course, it's likely that the auditor's systems were infected by a worm on the client's network, rather than the other way around, but running 3 systems known to be vulnerable to the same defect that they were spanking the client for was, pardon the pun, an oversight. In the last year or so, several incidents of auditors losing valuable client data including identity information have been reported, notably more than once incident involving Ernst & Young. So, have someone on your staff work closely with the auditors as a sponsor of the audit, or have an independent consultant watching over their shoulder for you. People sometimes get carried away in their exuberance to do great work, and other times are following bureaucratic procedures that just don't make sense. In either case, your sponsor should have veto power over any actions during the audit, to protect your data from accidental exposure. In case you're wondering, you don't need an "auditor for the auditor for the auditor" up an infinite chain. What we're really talking about here is a sponsor with veto power who isn't part of the audit team. This kind of outside watchdog can break the pattern of groupthink that causes people to run off with a half-baked idea and accidentally expose the data they are ostensibly trying to help you protect.