Noun meaning "an advertisment that poses as news"

Solution 1:

This type of hidden advertising is called commercial content or sponsored content, also known as native advertising .

Commercial content on the Guardian

Guardian News & Media produces a variety of content with funding from outside parties.

https://www.theguardian.com/info/2016/jan/25/content-funding

Native advertising is a type of disguised advertising, usually online, that matches the form and function of the platform upon which it appears.

https://en.wikipedia.org/wiki/Native_advertising

If you're looking for a single word, you might use advertorial :

an advertisement that imitates editorial format

http://www.merriam-webster.com/dictionary/advertorial

a newspaper or magazine advertisement giving information about a product in the style of an editorial or objective journalistic article.

ORIGIN 1960s (originally U.S.): blend of advertisement and editorial.

^{New Oxford American Dictionary}

‘Advertorial’

Advertorial content describes features that are paid for and controlled by the advertiser rather than by The Australian; they are subject to regulation by the Advertising Standards Authority.

http://www.theaustralian.com.au/help/commercial-content-overview

Solution 2:

Contorting the information a bit to match the request for a single word, several terms are in play. The most common, and contemporary, jargon term is apparently 'native':

native advertising Displaying an ad on a Web page along with regular content in a manner that does not distract the user. Contrast with "interrupt advertising," which requires users to cancel a message that demands their attention. See interstitial ad.

(Computer Desktop Encyclopedia. S.v. "native advertising." Retrieved September 14 2016 from http://encyclopedia2.thefreedictionary.com/native+advertising.)

Another polite term, more likely to be familiar to others than those involved in the buying and selling of such quasi-news, is 'sponsored', as mentioned in this Consumerist story:

Facebook began labeling certain shared links as “satire,” as a bit of hand-holding for its less-savvy users who can’t tell the difference between an actual news headline and one written by the writers of The Onion. But what Facebook really needs to do is start labeling so-called “native” or sponsored stories on non-satire sites....

(Consumerist, "If Facebook Is Going To Label Satirical Stories, It Should Be Calling Out Ads Posing As News Links", Sept. 9, 2014. Emphasis mine.)

A less polite yet not downright disparaging term from earlier print and broadcast media, which may survive in some newsrooms but which has not, evidently, carried over to internet news sites, is 'phantom copy':

“We used to call that ‘phantom copy’,” says Marquette University Professor Lawrence Soley. He has conducted several surveys measuring the pressures large advertisers put on print and broadcast newsrooms. “Essentially it’s a bonus ad,” he says. “Advertise with us and we’ll throw in phantom copy. It’s done very frequently by small weekly newspapers across the United States.”

(Grade the News, "Advertising Disguised as News", undated.)

For even less polite terms, aside from 'quasi-news' (with the sense used in the foregoing answer), a discreet silence is perhaps best.