New York (CNN) Ruby Sinreich knew "something didn't smell right" as soon as she responded to a Facebook invite this summer for the 2019 Women's March in Raleigh, North Carolina.

A web developer and long-time activist, Sinreich grew suspicious when she noticed the page was posting what she recently called "weird, partisan memes that seemed totally out of character." Then she saw that the event page was promoting the wrong date for the 2019 march.

No one she knew in the activism community in North Carolina seemed to know who was behind the event. Besides, it was August, months before January's Women's March, and local organizers had yet to post the details for the march online.

"This is *exactly* how the Russians/Republicans have been manipulating our communication, politics, and elections for over 2 years now," she wrote in a Facebook post in August in which she warned her friends about the page.

Sinreich wasn't alone. Activists in Maine, Vermont, and elsewhere began noticing similar event pages advertising marches in their cities and listing the wrong date.

But the pages were not run by the Russian trolls who meddled in the US' 2016 election , and have continued doing so since. They were run from Bangladesh, a CNN investigation has found — and they were designed to exploit Americans' interest in politics and protests in order to sell t-shirts.

In all, there were 1,700 separate Facebook pages designed to look like they were run by local Women's March organizers, a source familiar with Facebook's investigation into the issue told CNN.

While the vast majority of the pages and events had no followers or attendees, some of the fake events promoting the wrong march date became popular. Fake events for Philadelphia and Chicago received more than 10,000 RSVPs; the event posted for Seattle picked up more than 20,000. (As ever with numbers on social media sites, it is possible that at least some of the RSVPs came from fake accounts used to make a page seem more popular).

The network of fake pages highlights the increasing challenges facing both American activists and companies like Facebook as bad actors, both foreign and domestic, use social media platforms to tap into the highly charged and partisan nature of American politics for financial or political gain.

While the Bangladeshi group's motives appear to have been financial, rather than ideological, they used the same playbook and exploited some of the same vulnerabilities — the ability to create pages essentially anonymously online, and the tendency of all people to rush to support causes with which they agree — that Russian government-linked trolls utilized to sow division in the lead-up to the 2016 US presidential election.

Facebook removed the specific event pages that were advertising the wrong date for the march in late September and early October.

The Bangladesh group's use of the wrong date appears to have been an oversight. Still, it illustrates the negative effects that can come out of this kind of exploitation of American politics: The people doing it don't care about any cause but their own, and so don't worry about details that could have a real-world effect on the people they're taking advantage of.

"There are a lot of ways that it is damaging and dangerous. People show up on the wrong date and don't go to the actual event. People leave feeling angry and frustrated instead of feeling unified," Sinreich told CNN.

Other organizers told CNN that they communicate safety and emergency information through Facebook for their events. When a fake page that real activists have no control over becomes popular, it prevents them from reaching some people who might need that information.

Facebook acts

Soon after Facebook removed the fake events with the wrong march dates in late September and early October, a whole new network of pages began to emerge. Using data gathered by Benjamin T. Decker, a research fellow at the Shorenstein Center at the Harvard Kennedy School, CNN identified almost 100 new pages. Women's March activists with whom CNN spoke said they were not behind the pages.

"What is particularly notable about the relative sophistication of dozens of fabricated Women's March Facebook pages is the co-opting of official images and logos, hashtag hijacking, using pre-existing hashtags such as #womenswave to attract attention to the pages, as well as the localized targeting of urban, suburban, and rural communities across the country," Decker told CNN.

One of the fake Women's March events posted to Facebook that promoted the wrong date for January's march. The event has since been removed

After CNN provided Facebook with a list of the pages over the weekend, the social media network removed them. But by that point the company had already launched its own internal investigation into the network of scammers, and were working with organizers of the national Women's March to identify the fakes.

A source familiar with Facebook's investigation told CNN that more than 1,700 Facebook pages and corresponding events were created as part of the campaign and that the administrators of the pages were in Bangladesh.

Andy Stone, a Facebook spokesperson, said in a statement provided to CNN, "People need to be able to trust the connections they make on Facebook. That's why we have removed Pages and events associated with fake women's marches. These Pages and events appear to have been created in order to profit from people interested in the event by selling march-related merchandise. We continue to investigate, remove additional associated fake events and Pages, and take action against those involved in creating them."

A Woman's March spokesperson told CNN they were "grateful Facebook has been so responsive and helpful to us as we track and report these pages, so we can get back to our real work: organizing a women's wave to take this country back.

But local activists are frustrated with the social media company.

"Their customer service is lacking, you can't talk to a real human," Sara Gaba, the co-chair of Women's March Maine, told CNN.

Gaba and her colleagues noticed a fake Women's March event for Portland, Maine, with the wrong date, spreading on Facebook back in June.

Gaba told CNN that she and at least five of her colleagues reported the event to Facebook, but the page wasn't removed for months.

As an activist, she said, she remains concerned about these kinds of scams. "There is so much misinformation out there. How are people going to know to spot the fake pages when they look so real?"

Sinreich, in North Carolina, had the same experience in August when she reported a fake to Facebook.

So too did Women's March Vermont co-chair Kristen Vrancken when she noticed a fake event in August organized for Montpelier. Last week she spoke to Seven Days, a newspaper in Vermont , about the mystery of the fake group. Her story prompted CNN's wider investigation.

Why Bangladesh?

Some of the fake events linked to pages selling unofficial Women's March merchandise on Viralstyle and Teespring, websites that allow users to design and sell t-shirts and other merchandise without having to print or produce the merchandise themselves. While many of the pages CNN identified did not link out to merchandise sites, Facebook's investigation determined the network of pages were being run for financial gain.

Hundreds of LinkedIn users list themselves as being based in Bangladesh and affiliated with California-based Teespring.

More than a dozen LinkedIn users list themselves as living in Bangladesh and affiliated with Florida-based Viralstyle.

Some Bangladeshi designers and marketers use a Facebook group called "Viralstyle Bangladesh" to share tips on increasing sales through the site, including YouTube videos describing how to target Facebook ads.

CNN provided Viralstyle with links to several Women's March items that had been for sale on its platform before being removed. In a statement, a company spokesperson said, "Our system identified the user account associated with these campaigns to be fraudulent (via unverified email), and the account and campaigns created by it were ended immediately."

Of the Bangladesh Facebook group for its company, the spokesperson said, "When there is enough interest in our platform from a specific area of the world, we will usually create a specific group for that country or area. The main purpose of these groups is to provide support, training, and brand awareness."

Teespring didn't say if it had removed any Women's March merchandise.

"Teespring does not directly employ any creators or sellers. Bangladeshi users are self-employed, like the rest of Teespring's community. They use the platform and are not employed by the company," Teespring said in a statement provided to CNN.

A Women's March spokesperson told CNN that "many of these fake pages are used to sell merchandise, with the proceeds benefiting individuals instead of our movement. The efforts to capitalize on movement work isn't new, but it is frustrating, particularly as we make an effort to only sell ethically sourced and produced merchandise — a rule these imposter pages don't abide by."

CNN also identified pages tied to the fake network on the blogging platform Medium and the ticketing service Eventbrite.

Eventbrite had removed the events before CNN contacted it; Medium removed the pages after being contacted by CNN. Neither company would say who was behind the pages, or if they were run from outside the United States.