Hackers Are Stealing Session Cookies To Bypass Multi-factor Authentication

Slashdot reader storagedude writes: Hackers are stealing cookies from current or recent web sessions to bypass multi-factor authentication (MFA), according to an eSecurity Planet report. The attack method, reported by Sophos researchers, is already growing in use. The "cookie-stealing cybercrime spectrum" is broad, the researchers wrote, ranging from "entry-level criminals" to advanced adversaries, using various techniques. Cybercriminals collect cookies or buy stolen credentials "in bulk" on dark web forums. Ransomware groups also harvest cookies and "their activities may not be detected by simple anti-malware defenses because of their abuse of legitimate executables, both already present and brought along as tools," the researchers wrote. Browsers allow users to maintain authentication, remember passwords and autofill forms. That might seem convenient, but attackers can exploit this functionality to steal credentials and skip the login challenge. Behind the scenes, browsers use SQLite database files that contain cookies. These cookies are composed of key-value pairs, and the values often contain critical information such as tokens and expiration dates. Adversaries know the exact name and location of these files for all major browsers such as Chrome, Firefox, and even Brave, on various operating systems. That's why the attack can be scripted. It's not uncommon to find such scripts along with other modules in info-stealing and other malware. For example, the latest version of the Emotet botnet targets cookies and credentials stored by browsers, which include saved credit cards. According to the Sophos researchers, "Google's Chrome browser uses the same encryption method to store both multi-factor authentication cookies and credit card data." To gain initial access, attackers can also perform phishing and spear-phishing campaigns to implant droppers that can deploy cookie-stealer malware stealthily. The cookies are then used for post-exploitation and lateral movements. Cybercriminals can use them to change passwords and emails associated with user accounts, or trick the victims into downloading additional malware, or even deploy other exploitation tools such as Cobalt Strike and Impacket kit. Users should not use built-in features to save passwords unless the browser encrypts them with, at least, a master password. It's recommended that users uncheck the setting called "remember passwords," and users should probably not allow persistent sessions as well. Developers can be part of the problem if they don't secure authentication cookies properly. Such cookies must have a short expiration date. Otherwise, the persistent authentication could turn into a persistent threat. You can have great security processes and still get hacked because the cookies do not have the necessary flags (e.g., HttpOnly, Secure attribute). For example, authentication cookies must be sent using SSL/TLS channels. Otherwise the data could be sent in plain text and attackers would only have to sniff traffic to intercept credentials.

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