The objective of the approach should be to detect malware that slips by the signature and static analysis systems, taking you from 10% to 20% detection back up to the glorious days of 60% to 80%. You'll even encounter some vendors claiming their solution will take you to the oxygen-deprived altitude of 99% to 100%.

Unfortunately, the reality of the situation is considerably different from the marketing pitch. The combination of signature detection, static analysis and automated dynamic analysis systems for malware detection yields different levels of success depending on the type of threat encountered.

Consider the corporate world which faces three separate threat categories: generic Internet threats (such as any target, anywhere on the Internet, with no victim selection); infiltration threats (such as malware crafted to work against typical/average corporate defense in depth strategies); and espionage threats (such as malware tools tuned to operate within your organization).

For generic Internet threats, the combination of antivirus defenses probably thwarts 80% to 90% of threats within one week of release by criminal authors. For infiltration threats orchestrated by criminals looking for bigger monetary yields, those same defenses thwart around 40% to 50% of the malware they employ. Meanwhile, for targeted espionage threats, you'd be hard pressed to detect up to 10% of the malware tools used to conduct such an attack.

The numbers are scary - and they should be - because they reflect the reality of the situation and not some idealized marketing fluff. But context is also important here. Malware threats that come via the front door (for example over unencrypted HTTP via a Web browser, or as email attachments) are the most convenient from a threat analysis perspective and, from purely a volume perspective, you can expect 90% to 95% of those binaries to be generic Internet threats.