Adware infections net the purveyors of slimeware software around $3 a year for each infected PC, according to estimates from anti-spyware firm Webroot Software. Using this figure and stats from its own malware auditing services, Webroot guesstimates the illicit advertising market underpinned by adware infection of home and business PCs could be worth up to $1.6bn a year.
According to Richard Stiennon, VP of threat research at Webroot, the illicit ad market enjoys approximately the same growth rate as the legitimate market. But that's where the similarities end. "It [adware] has a similar bus model and some of the same affiliates as the spam industry. Adware is not just used to serve up ads for penis pills though. Sometimes legitimate companies - whether they realise it or not - purchase ad views from adware firms," he said.
It's hard to square Webroot's $1.6bn estimate with the observable size of adware market. The company looks to be on much firmer ground in working out how much adware agent makes its owner, because its assumptions derive from the public disclosure of firms operating in the market.
Stiennon notes that adware company Avenue Media claims the 2m PCS running its software brought in $7m of revenue per year in its lawsuit against rival DirectRevenue, whose VX2 package allegedly disables Avenue Media's software. Claria (the firm formerly known as Gator) revealed that its software was loaded onto 40m PCs, bringing in $90m in revenue a year in public fillings made in 2003.
From these two data points we get an estimate that each item of adware generates between $2.25 and $3.50 per year from each infected PC. That's an average of $2.95 per-infection-per-year, Stiennon says in a recent opinion piece on CIO Update. But simply averaging the two figures is a questionable statistical assumption and worse is to follow.
Webroot's spy audit suggests an average PC on the net (whatever that is) has at "least two pieces of adware on it". ClickZ Stats indicate that there are 280m active PCs on the internet. Multiplying the number of PCs by the average number of adware items on each by the revenue per app figure allows Stiennon to guesstimate that the illicit advertising market is worth $1.6bn a year.
This calculation assumes a uniform distribution of spyware, among other statistical sins. Estimates on the damage caused by malware are a notoriously inexact science. The same seems to apply to looking at the adware market.
Stiennon told El Reg that machines loaded with more than three pieces of adware slow down to the extent they are less effective cash generators. This may be the case but we remain unconvinced about Webroot's headline figure for the illicit ad market of $1.6bn, which it compares to the $10bn a year pulled in by Google, Yahoo! DoubleClick et al. ®