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Address Bar Spoofing Vulnerability Found in Several Browsers

Chrome, Firefox and other web browsers are plagued by vulnerabilities that can be exploited to spoof their address bar. Some of the affected vendors are still working on addressing the issues.

Pakistan-based researcher Rafay Baloch discovered that the address bar in Google Chrome, also known as the omnibox, can be tricked into flipping URLs.

The problem, which affects Chrome for Android, is related to how Arabic and Hebrew text is written from right to left (RTL). If an attacker’s URL starts with an IP address and it contains an Arabic character, the URL’s host and path are reversed.

For example, the URL 127.0.0.1/ا/http://example.com becomes http://example.com/‭ا/127.0.0.1 as it contains the “ا” character, the Arabic letter alef, which causes the URL to be rendered RTL. The method works with other Arabic characters as well, as long as they are the rightmost “strong” character – the numbers and the dots in the IP address are considered “weak” characters.

“The IP address part can be easily hided specially on mobile browsers by selecting a long URL (google.com/fakepath/fakepath/fakepath/... /127.0.0.1) in order to make the attack look more realistic,” Baloch explained in a blog post. “In order to make the attack more realistic unicode version of padlock can be used in order to demonstrate the presence of SSL.”

A similar vulnerability was also found in Firefox for Android (CVE-2016-5267). However, in Firefox’s case, the URL does not need to start with an IP address – the only requirement is that it contains Arabic characters that cause the URL to flip. For instance, http://عربي.امارات/google.com/test/test/test becomes google.com/test/test/test/عربي.امارات.

Google has known about this issue for more than a year. Baloch said he informed Google about its presence in the Android version of Chrome in May, and the company addressed it in late June. Mozilla patched the flaw in Firefox for Android on August 2.

Baloch told SecurityWeek that other browsers are affected as well, including desktop versions. In the case of Firefox and Chrome, the vulnerability only impacts the mobile versions.

The researcher has earned $3,000 from Google, $1,000 from Mozilla and $1,000 from an unnamed browser vendor that is currently working on fixing the bug.

Related: Address Bar Spoofing Bugs Found in Safari, Chrome for Android

Related: Google to Fix Address Spoofing Bug in Chrome

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Eduard Kovacs (@EduardKovacs) is a contributing editor at SecurityWeek. He worked as a high school IT teacher for two years before starting a career in journalism as Softpedia’s security news reporter. Eduard holds a bachelor’s degree in industrial informatics and a master’s degree in computer techniques applied in electrical engineering.