A young hacker from the Czech Republic discovered a security loophole in one of Google's support applications.
If maliciously exploited, the error could allow hackers to steal cookies from Google employees for internal applications and seize their accounts. Extremely compelling e-fishing attempts could be launched, which would give them access to many other parts of Google's internal network.
The security loophole was discovered by researcher Thomas Orlita in February 2019. It was fixed in mid-April, but has only just been published.
The vulnerability was cross-site scripting (XSS), and was found in Google's billing portal, a public domain that redirects Google to the business users of the billing platform.
Most cross-site scripting (XSS) vulnerabilities are not considered as dangerous but there are cases that can lead to very serious problems.
One of these cases was the discovery of Orlita. The researcher said that a malicious user could upload his own files to the Google Invoice Submission Portal, via Upload Invoice.
Using a proxy the attacker could prevent the Google Invoice Submission Portal from changing the PDF document (after the submission and validation of the form) and modifying it into HTML, with malicious XSS load.
The malicious document would be stored in Google's billing backend and wait for someone to open it.
"XSS runs on a googleplex.com subdomain and while the employee is logged in, the attacker can access the subdomain control panel from where invoices can be viewed and managed," Orlita told ZDNet.
"Depending on how cookies are configured on googleplex.com, it may be possible to access other internal applications hosted on this domain," the researcher added.
So since most of Google's internal applications are hosted on the googleplex.com domain, this gives attackers a lot of possibilities.
Of course, like most security vulnerabilities XSS, the risk of error depends on the hacker's skill level, and his ability to carry out more complex attacks.
For more technical details you can read Orlita publication.