An interesting story on Slashdot this morning is about a Brazilian report [and here in the original Portuguese] into the effectiveness of free anti-virus software against non-English threats. Admittedly, they only tested six, all of which were free, but the results were pretty disappointing, especially compared to a set of independent statistics (taken from “Virus Bulletin“):

Name % detected (in the report) % detected (independent stats1)
Avira 78% 99.7%
AVG 75% 93%
Panda Cloud 70.6% NDA
Avast! 69.8% 98.2%
PC Tools 64.7% NDA
Microsoft Security Essentials 13.4% 87.1%

1 These results are from 2009, but give an indication.

So, there are a number of things to draw from this, aside from the fact that no paid-for software was tested. Even if there is a large margin of error, the discrepancy in the results is quite stark and might make large organisations, particularly multi-nationals, re-consider their AV protection. What works in one part of the world may not be quite so effective in another.

It’s also worth mentioning that most anti-virus products will use a variety of techniques to detect malicious software, from signatures to heuristics and these results will almost certainly not reflect real-world detection rates if everything is turned on and additional software, like firewalls and anti-spyware products are used.