Spammers have found a way to abuse a URL shortener service destined for US government social media activities in order to craft rogue .gov URLs for work-at-home scams.
Security researchers from Symantec have detected a new email spam campaign that tries to trick users into visiting URLs with the 1.usa.gov domain name. This domain was created as the result of a partnership between the USA.gov, the US government's official Web portal, and the Bitly URL shortener service.
According to a how-to page on USA.gov, when anyone uses Bitly.com to shorten URLs that end in .gov or .mil, the service will generate shorts URL under the 1.usa.gov domain.
"A short URL could take a user to a trustworthy site or a spam site, but a user would have no way of knowing before he or she clicks. That's why USA.gov has made it easy for people to create short, trustworthy .gov URLs that only point to official US government information," the Web page explains.
However, it seems that spammers have figured out a way to abuse the service and the inherent trust associated with .gov URLs by exploiting open redirect scripts found on some .gov websites.
Redirect scripts are used by website owners to track clicks to third-party URLs listed on their websites, to display warnings to users that they are leaving the website or for other purposes. However, these scripts are often left unprotected and open to any destination, which results in so-called open redirect vulnerabilities.
"By using an open-redirect vulnerability, spammers were able to set up a 1.usa.gov URL that leads to a spam website," Symantec researcher Eric Park said Friday in a blog post. In particular, the spammers used an open redirect script from the State of Vermont's Department of Labor website - labor.vermont.gov, he said.
First, the spammers behind this campaign created scam websites masquerading as financial news sites that contain articles about work-at-home opportunities. This type of scam has been around for years and its goal is to convince users to pay for starter kits or service subscriptions that would allegedly allow them to start making money on the Internet by working from their home computer.
The scam websites used in this campaign were hosted on domains like consumeroption.net, consumerbiz.net, workforprofit.net, consumerneeds.net, consumerbailout.net and others.
The spammers exploited the open redirect vulnerability on the labor.vermont.gov website to create URLs of the form labor.vermont.gov/LinkClick.aspx?link=[scam website]. These URLs were then passed through Bitly in order to generate 1.usa.gov short URLs, therefore creating a two-step redirect chain.
"While taking advantage of URL shorteners or an open-redirect vulnerability is not a new tactic, the fact that spammers can utilize a .gov service to make their own links is worrisome," Park said.
Public statistics provided by the Bitly for the rogue 1.usa.gov URLs used in this spam campaign showed that the links had been clicked 43,049 times between 12 and 18 October, with a significant spike in click volume on 18 October.
"The top four countries on a daily basis were the United States, Canada, Australia, and Great Britain," Park said. "In aggregate, the United States made up the biggest slice with 61.7 percent of the clicks."
Gov URLs might inspire a higher degree of trust. However, users should always exercise caution when opening links, regardless of where they appear to be pointing to, Park said.