Penetration testers put their pants on just like the rest of us, one leg at a time. Except once their pants are on, they break into computers. Not all pen testers, however, are created equal.
Whether you're hiring someone for your security team or you're engaging a consulting firm to conduct a third-party assessment, it's valuable to know how to gauge your pen tester's level of expertise. Don't get charged top dollar for second- or third-rate talent. When choosing any other professional, like a doctor or lawyer, you care more about the expertise and experience of the person doing the work than how many golf tournaments his company sponsors. You also probably don't want the lawyers with the most billboards (or any billboards for that matter). This is why pen tester selection is critical.
Novice Penetration Testers
Most pen testers -- roughly four out of every five -- fall into the novice category. A novice pen tester could be an entry-level security professional just learning the ropes or a more experienced person who simply lacks the skill or motivation to press beyond the simplest types of testing. In any case, novice pen testers tend to exhibit a handful of defining traits: tool-centric testing approach, an overreliance on checklists, and failure to perform proper manual testing.
Failure Of The Tool Jockey
Nobody wants to hire a pen tester who does little more than run a tool and rewrite a canned report. Yet a great deal of the "pen testing" that is sold to unknowing customers amounts to just that and little more. Novice, or proficient, penetration testers often use tools as an end instead of a means to an end. When a scan is done, so is the test.
These testers will often miss more sophisticated or complex vulnerabilities. This is because they don't yet know how to recognize them, they aren't aware that certain vulnerabilities even exist, or they don't know how to properly validate what they do find due to lack of experience or expertise. In addition to being able to use tools, a pen tester must also be able to interpret the tool results correctly.
Another indicator of skill level is how well a person can explain what he does find: the root cause of the vulnerability, the validation process, and the remediation recommendation. A novice can usually provide a canned response, but if you ask him to describe the issue in light of your specific situation or in a nonstandard circumstance, he will often struggle to provide a coherent response.
The greatest danger of the novice's tool-centric approach is the fact that his (and thus your) results will be skewed in light of the tool's own limitations. Many novice penetration testers fall into this trap where they depend entirely on the automated tool to provide them with a list of vulnerabilities.
If you're interviewing someone for a pen testing role on your team, a dead giveaway that they're a novice is if he mentions that he "really likes [insert name of tool]" or that he would "really like to learn how to use [insert name of tool]." That's like interviewing a carpenter to work on your construction team and hearing him say that he really likes hammers or that he wants to learn how to use a measuring tape.
More advanced pen testers know that tools are tools, and just a means to an end. Novices usually give themselves away by showing an undue reverence for tools.