How I am able to hijack you.

or rather: How I am able to hijack your autosuggestions in Google Search.

Google Search has been going through a lot lately due to the outstanding XSS finding that was done by Masato Kinugawa. In this brief article I wanted to share with you, maybe not as exciting as the finding mentioned above, but for sure a very cool bug that I discovered when sniffing around Google Search lately.

The title with the intro image at the side should already reveal what the vulnerability that I found is about. It’s manipulation of one’s autosuggestion list that pops out when they’re searching for phrases using the Google Search website.

What I discovered is that the only step required to add an exact phrase into the mentioned list is simply visiting the URL https://www.google.com/search?q=phrase . Simple as that. The attacker can just make a few requests in the background and put anything into your autosuggestions without you even noticing.

Why would the attacker want to achieve this?

The answer to this question is not trivial. However, I found a few cases that could impact the users in one way or another. These cases are as follows.

Advertising the product. The company could try to advertise their product by flooding the visitor’s autosuggestion list, so when they’re searching for a specific item the company brand would show up before the user even hits the ENTER.

Phishing. The attacker could try to put the phishing websites at the top of the list, e.g. facebook⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀site:facehook.tk that would steal their credentials when attempting logging in.

facebook⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀site:facehook.tk

Annoyance. The reason behind the flooding doesn’t necessarily have to pose any security impact to do damage. For example, the only goal that the attacker could have in mind could be to flood someone’s autosuggestion list with thousands of phrases. Just to annoy. Clicking a thousand times ‘remove’ could be really frustrating if you didn’t happen to know a way to clear all the search history at once.

Embarrassment. Another possible goal is to cause the victim to feel embarrassed. Imagine someone presenting in front of the audience and in the middle of a speech, when attempting searching for something, very inappropriate results show up. I can’t imagine a bigger embarrassment during the speech :)

Security issue or not?

In my opinion, the finding is a security issue in a way that could impact a lot of users. Nevertheless, the Google team didn’t share that point of view, which I fully respect, and the issue was closed as Won’t Fix (Intended behavior) .

The flooding one’s autosuggestion doesn’t seem to have a great motivation factor for the attacker, what would they gain out of this? We think the issue might not be severe enough for us to track it as a security bug.

I probably should also mention that this vulnerability was part of a bigger report that was related to clickjacking the Google reCAPTCHA which is a bridge to many other attacks that will also appear on my Twitter wall soonly. Follow me on Twitter to stay up to date @terjanq.