Uber has pulled its petition sites offline after a hacker exploited web vulnerabilities lodging 100,000 fake votes and redirecting visitors to rival Lyft.

The hacker known only as "Austin" could not be reached at the time of writing. Uber has been contacted for comment.

Austin says the petition site Uber hoped to use to lobby for access to Market Street in San Francisco allowed him to stuff the polls and run cross-site scripting through the entry fields which were executed in a live form.

The hack was live for two hours in which it redirected visitors to Lyft.com.

"Thanks Uber for making it so easy to manipulate your website," the hacker says on a blog .

"Whoever wrote your script was in a hurry to get home [and] whoever developed your webpage literally copied and pasted code from an online tutorial that promotes itself as being very simple code.

"I can take over their website. And I did."

The hacker contacted Uber prior to publishing the blog allowing the company to pull all of its petitions offline and redirecting users to what appeared to be an employee login page.

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He says he posted some 100,000 bogus signatures in three hours and used various scripts to demonstrate how an attacker could have forced the site to run malicious code to target web visitors.

"Now that we know we can insert code onto their page and it seems to work well, we know our only limitations are the limitations of code itself," he says.

It is unknown if the entries for the petitions are exposed or how deep the security flaws are in Uber's network.

Austin says Uber should rate limit petition submissions and sanitise inputs. ®