Counterfeit and harmful ads are a big problem online. (ALAMY)

Social networks are a key place for marketers and advertisers to reach consumers who may be interested in their products. But as online advertising grows, companies also have to consider how to fight the problem of keeping bad advertisements — ads for counterfeit goods, spam advertisements or ads that link to malware — off their networks as well.

On Thursday, Google, Facebook, AOL and Twitter announced they’ve joined the Interactive Advertising Bureau in creating the Ads Integrity Alliance. The group will work together to share information and establish policy recommendations to deal with counterfeit, scammy and malware-laden advertisements.

The initiative will have the operational support of StopBadware, a nonprofit that started at Harvard’s Berkman Center for Internet & Society. The new initiative will “develop industry policies and a channel for information sharing” between the member groups to deal with bad ads, said Maxim Weinstein, the president of StopBadware. Counterfeit ads are bad for everyone, Weinstein said, because they give platforms a bad name and can discourage users from clicking on any online ads at all.

Online ads are often screened by humans and computers, but questionable ads can slip through the cracks. For example, Facebook spokesman Frederick Wolens said that less than 0.5 percent of Facebook users — around 4.5 million of Facebook’s 901 million users — experience spam on any given day.

Eric Feinberg, a social marketer, started noticing bad ads on his Facebook page in January 2012.

“At first I decided to see if it would stop,” he said. “Then I started asking people from work, ‘Are you getting these weird ads?’”

He found more of his co-workers and Facebook friends were seeing the ads, too. Even more disturbing for Feinberg, he found that he could manipulate what he posts on his wall or in his photo albums to generate ads for specific counterfeit goods. The ads change depending on what he’s marketing on his page — when he talks about baseball, ads for baseball jerseys pop up, when he talks about football, ads for football jerseys appear. He’s even seen his own pictures featured in the ads on other’s pages.

Feinberg has documented the ads he’s seen on his page for months, prompting him to found a group that calls attention to counterfeit ads — the Fans Against Kounterfeit Enterprise, or FAKE.

He reports the ads to Facebook, he said, but notices that the same products were popping up from different sites with slightly different Web addresses.

That’s a common problem, Weinstein said, but he believes that having companies share the information about ads they see can help with the problem.

“The weak link in criminal behavior is the criminals — there’s a human being making decisions. So a person may be the common thread across 10,000 Web sites that don’t seem to have any obvious link. But somewhere there should be a link to give people a clue about what's going on,” he said.

Wolens said in a statement that Facebook strives to “create a trusted environment for our users and advertisers” and that it hopes joining the alliance will help protect more users across the Internet.

Google Public Policy Manager Eric Davis also said that information sharing is key to fighting the ads.

“We want everybody to have that data, not just one party, so everyone is protected and people can’t so easily game the system from hopping from network to network,” he said.

Bradley Shear, an attorney who works with Feinberg and specializes in privacy law said that fake ads are also a serious privacy concern.

In the case of scammers, “who knows what they’re doing with their data,” he said, particularly since it’s easy for scammers to disguise where and how they work.

Feinberg said that he believes the government should begin looking into how sites review ads, to make sure that users aren’t tricked into clicking on the ads. As a marketer, Feinberg has also had reservations about posting his promotional material to Facebook — his primary marketing tool — for fear that bad ads will show up alongside his legitimate marketing efforts.

“It’s hurt my income,” he said.

(Washington Post Company chairman Don Graham sits on Facebook’s Board of Directors.)

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