What Is a Browser-in-the-Browser (BitB) Attack?

A browser-in-the-browser (BitB) attack represents a novel phishing method that mimics a login interface within a parent browser window, presenting a forged domain to steal login credentials. This technique primarily targets the single sign-on (SSO) authentication model, allowing users to access various websites using existing accounts from platforms such as Google, Facebook, or Microsoft.

In contrast to traditional phishing schemes, where users are redirected to counterfeit websites resembling authentic ones, the BitB attack operates within the original website. Users encounter a pop-up window resembling the SSO service they intend to use. However, this pop-up is crafted by the attacker using HTML, CSS, and JavaScript tools, enabling it to display any URL, including a legitimate one, to deceive users into believing they are on a secure page.

The BitB attack leverages users’ trust in the SSO authentication model and their tendency to overlook browser details, making it highly effective. Should users input their credentials in the counterfeit pop-up, the information is transmitted to the attacker’s server, potentially redirecting users to the authentic service or presenting them with an error message.

How does a Browser-in-the-Browser Attack Work?

To carry out a BitB attack, the attacker must first lure the user to a malicious or compromised website hosting a phishing page on the attacker’s server. This page generates a pop-up window via JavaScript, replicating the appearance and functionality of a browser window, and presents a counterfeit login form resembling the desired SSO service.

Within the simulated pop-up window, the attacker can manipulate the displayed URL using JavaScript code, showing any desired address, such as https://accounts.google.com or https://login.microsoftonline.com. Users may fail to realize that the URL isn’t actually loaded in the pop-up window but is merely displayed as an image or text. Additionally, users may overlook the absence of SSL certificates or other typical security indicators in the pop-up window.

If the user falls victim to the BitB attack and submits their credentials in the counterfeit login form, the information is transmitted to the attacker’s server through an AJAX request or hidden form submission. Consequently, the attacker can exploit these credentials to access the user’s legitimate service account or carry out further malicious activities, such as identity theft or account takeover.

Real-World Examples of BitB Attacks

The BitB attack was initially brought to light and detailed by an information security researcher and pentester identified as mr.d0x on their website in April 2022. They demonstrated how this attack could successfully imitate Google’s SSO login page, enabling the theft of users’ credentials.

Recently, hackers employed a ‘Browser-in-the-Browser’ technique to specifically target Steam credentials. According to reports, this method included a counterfeit green lock symbol, a falsified URL field capable of being copied, and even an additional fraudulent Steam Guard window for two-factor authentication. Some of the Steam accounts compromised in these assaults were estimated to be worth between $100,000 and $300,000.

Moreover, Ghostwriter, an operator based in Belarus known for orchestrating disinformation campaigns in Europe, has adopted the browser-in-the-browser approach to target organizations in Ukraine and other regions. This campaign is just one of several connected to Ukraine that Google has been monitoring, involving various threat actors, including state-sponsored groups from Iran, China, North Korea, and Russia, alongside criminal and financially motivated entities.

How to Protect Yourself Against BiTB Attacks?

The BitB attack represents a sophisticated and hazardous phishing technique that can evade many conventional security measures, even fooling cautious users. However, there are several steps individuals can take to safeguard themselves from this threat:

• Attempt to resize the window. If unable to do so, it’s likely a fraudulent browser window.
• Fake BitB browser windows may exhibit unexpected behavior when closed, minimized, or maximized.
• Pay attention to discrepancies in the appearance and behavior of fake browser windows compared to your operating system and browser theme.
• Scrutinize the details of pop-up windows, including size, position, and the behavior of elements. If anything appears suspicious, close the window and report it.
• Exercise caution when clicking on links or opening documents from unfamiliar or suspicious sources.
• Install a security-focused browser extension capable of automatically detecting and blocking such phishing attempts.
• Ensure your browser is regularly updated with the latest security patches and updates as prompted.
• Enable two-factor authentication (2FA) for all critical services to add an extra layer of security.

FAQ’s

What sets apart a Browser-in-the-Browser (BitB) attack from traditional phishing methods?

BitB attacks occur within the original website, where users encounter a pop-up window resembling the desired Single Sign-On (SSO) service. This contrasts with traditional phishing, where users are typically redirected to counterfeit websites.

How does a BitB attack unfold?

In a BitB attack, users are directed to a malicious or compromised website containing a phishing page. This page generates a pop-up window via JavaScript, displaying a counterfeit login form resembling the SSO service. If users input their credentials, the information is sent to the attacker’s server, potentially leading to identity theft or account compromise.

Can users spot a BitB attack?

Users may notice signs such as the inability to resize the pop-up window, unexpected behavior upon closing or minimizing, or discrepancies in appearance compared to their operating system or browser theme. Additionally, they should scrutinize the URL and security indicators of the pop-up window.

Have there been documented instances of BitB attacks in the real world?

Yes, there have been reported cases of BitB attacks targeting platforms like Google and Steam. For example, attackers have successfully replicated Google’s SSO login page and crafted counterfeit Steam Guard windows for two-factor authentication.

How can individuals safeguard themselves against BitB attacks?

Users should exercise caution when interacting with links or documents from unfamiliar sources. Additionally, installing security-focused browser extensions, keeping browsers updated, and enabling two-factor authentication for crucial services can help mitigate the risk of BitB attacks.

Conclusion

BitB attacks pose a serious threat, exploiting users’ trust in SSO authentication to steal login credentials within the original website. Despite their sophistication, users can defend against them by staying vigilant, recognizing the signs, and implementing robust security measures like two-factor authentication. Remaining proactive is crucial in safeguarding against these evolving cyber threats.