Two-factor authentication (2FA) is widely regarded as one of the most effective ways to secure online accounts. By requiring not just a password but also a second form of verification, such as a code sent to your phone or an app, 2FA adds an extra layer of security. However, while it significantly strengthens account protection, it is not foolproof. Hackers have devised several methods to circumvent or exploit vulnerabilities in two-factor authentication systems. Here’s how it happens:
1. SIM Swapping
One of the most common methods hackers use to bypass 2FA is SIM swapping, also known as SIM hijacking. In this attack, the hacker convinces a mobile carrier to transfer the victim’s phone number to a new SIM card that the hacker controls. Once the number is transferred, the hacker can intercept any SMS-based authentication codes sent to the victim, allowing them to bypass 2FA protections.
The hacker usually gathers personal information, such as a Social Security number or address, through phishing attacks or by purchasing it on the dark web. They then contact the victim’s phone service provider, pretending to be the victim, and request the phone number transfer. This type of attack highlights one of the inherent weaknesses in SMS-based 2FA: it relies on the security of the mobile carrier.
2. Phishing Attacks
Phishing attacks are another common method for bypassing two-factor authentication. In these attacks, hackers trick users into entering their login credentials and 2FA codes on fake websites that look identical to legitimate login pages. These fake sites are often sent via email or text messages that appear to come from trusted services.
When the victim enters their password and 2FA code on the fake site, the hacker can immediately use the credentials and code to log in to the real account. Some sophisticated phishing kits even work in real-time, capturing the 2FA code and instantly relaying it to the actual login system before it expires. This is known as a “man-in-the-middle” attack.
3. Man-in-the-Middle Attacks
A more technical variation of phishing is the “man-in-the-middle” (MITM) attack. In this attack, the hacker intercepts communication between the user and the service they are trying to log into. The attacker sets up a proxy between the victim and the legitimate service, capturing both the login credentials and the 2FA code as the victim enters them.
MITM attacks can happen over unsecured Wi-Fi networks or through malicious software installed on the victim’s device. Once the hacker has intercepted the 2FA code, they can immediately log into the victim’s account.
4. Malware Attacks
Hackers can also use malware to bypass 2FA. For instance, malware installed on a victim’s device can capture both passwords and authentication codes as they are entered. Keyloggers, for example, record everything the user types, including their login credentials and 2FA codes.
Some malware, like banking trojans, can even intercept SMS messages or generate fake browser overlays that trick the user into entering their authentication information. Once the hacker has this data, they can log in to the victim’s account as if they were the legitimate user.
5. Brute-Force Attacks on Backup Codes
Many 2FA systems offer backup codes for times when users are unable to access their 2FA device. While these codes provide a convenience, they can also be a vulnerability. If a hacker manages to obtain these backup codes—either through a data breach or a brute-force attack—they can bypass 2FA altogether.
While two-factor authentication is a robust security measure, it is not invulnerable. SIM swapping, phishing, malware, and man-in-the-middle attacks are just some of the methods hackers use to bypass 2FA. To mitigate these risks, it’s important to use more secure forms of two-factor authentication, such as hardware tokens or app-based authenticators, and stay vigilant against phishing and malware attacks.
And if you’d like personal assistance, or a full security audit, please book a call at Hacked.com today.
Featured image by Midjourney and Jonas Borchgrevink.
