New Google Cookies Exploit Allows Access After Password Reset

A Critical Google Cookies exploit involves manipulating or stealing user cookies, which store authentication information, to gain unauthorized access to accounts. 

Hackers exploit this illicit mechanism to:-

• Impersonate users
• Hijack sessions
• Gain control over sensitive information
• Gain unauthorized access to websites
• Gain unauthorized access to applications

A developer, PRISMA, discovered a major Google cookie exploit in Oct 2023 that allows persistent access post-password reset. A threat actor later integrated it into Lumma Infostealer, causing a ripple effect across malware groups.

Cybersecurity researchers at Cloudsek recently identified a new critical Google Cookies exploit that enables threat actors to persistently gain Google access after a password reset.

While researchers discovered this critical flaw by using “HUMINT,” and the root of the exploit has been discovered at “MultiLogin,” it’s an undocumented Google OAuth endpoint.

Google Cookies Exploit

On Oct 20, 2023, CloudSEK’s XVigil found ‘PRISMA’ unveiling a potent 0-day solution for Google accounts on Telegram:

• Session Persistence: Stays valid after a password change, bypassing security.
• Cookie Generation: Creates valid cookies for uninterrupted access.

Malware reverses to target Chrome’s WebData token_service table that helps in extracting:-

• Tokens
• Account IDs

Besides this, the table holds crucial columns like:-

• GAIA ID (service)
• Encrypted_token

Decryption uses Chrome’s Local State encryption key that is stored in the “UserData directory,” which mirrors the password encryption.

Chromium’s source code unveils the MultiLogin endpoint, an internal sync mechanism for Google accounts. 

It aligns browser account states with Google’s authentication cookies for a consistent user experience. Besides this, several attempts were made to locate it using Google Dork, but all of them were unsuccessful.

The MultiLogin endpoint manages simultaneous sessions by accepting account IDs and auth-login tokens.

This undocumented MultiLogin endpoint, a crucial part of Google’s OAuth system, allows for the regeneration of cookies. 

Lumma’s sophisticated approach involves encrypting the token: GAIA ID pair, blackboxing the exploit and adding secrecy to its core mechanics.

Black boxing serves two purposes, and here we have mentioned them:-

• Protection of the Exploit Technique
• Evasion of Detection

Lumma’s sophisticated exploit manipulates the token: GAIA ID pair, enabling continuous cookie regeneration for Google services. Alarming is its persistence post-password reset, which allows:-

• Prolonged account exploitation
• Unnoticed account exploitation

Encrypting the key component signals a shift towards advanced, stealth-focused cyber threats, highlighting the stealth and protection of exploit methodologies in malware development.