Basic ping sweeps and port scans aside, the security tests run against networks and Windows hosts can dramatically affect performance and usability.
Scanning everything at once and scanning systems during peak production hours looks good on paper -- especially if time and efficiency is critical. The problem is many security scanning tools generate tons of traffic that can saturate Internet connections, eat up server and workstation processor cycles and fill up log files.
If you're unsure of exactly what your testing tools are throwing at your network, install a network analyser on your local test system or on a system you're testing and see what's dished out. You'll be amazed. Most modern hardware has enough oomph to handle this testing, but once you factor in regular traffic, the impact on the business can be drastic. There's also the issue of certain tools exploiting the vulnerabilities they find. This can create a denial-of-service or information integrity situation. Even manual checks performed at a snail's pace can create problems.
Some of the side effects are out of your control -- especially if you're using low-quality tools or poking and prodding poorly written software. Plan your testing carefully and time things out to minimise complaints and downtime when the pipelines do get filled up or systems crash.
Security assessments and five mistakes to avoid
Step 1: Relying on audit checklists and automated tools
Step 2: Not considering the side effects of your tests
Step 3: Not looking at the whole picture
Step 4: Spending too much time trying to fix everything
Step 5: Assuming testing once is enough
About the author: Kevin Beaver is an independent information security consultant, speaker and expert witness with Atlanta-based Principle Logic LLC. He has more than 19 years of experience in IT and specialises in performing information security assessments revolving around compliance and IT governance. Kevin has authored/co-authored six books on information security including Hacking For Dummies and Hacking Wireless Networks For Dummies (Wiley) as well asThe Practical Guide to HIPAA Privacy and Security Compliance (Auerbach). He's also the creator of the Security On Wheels audiobook series. You can reach Kevin at firstname.lastname@example.org>.