Meta Breach Incident Score: Analysis & Impact (MET5592555112125)

In this Rankiteo incident briefing, we review the Meta breach identified under incident ID MET5592555112125.

The analysis begins with a detailed overview of Meta's information like the linkedin page: https://www.linkedin.com/company/instagram, the number of followers: 11513481, the industry type: Software Development and the number of employees: 140153 employees

After the initial compromise, the video explains how Rankiteo's incident engine converts technical details into a normalized incident score. The incident score before the incident was 765 and after the incident was 765 with a difference of 0 which is could be a good indicator of the severity and impact of the incident.

In the next step of the video, we will analyze in more details the incident and the impact it had on Meta and their customers.

WhatsApp (Meta Platforms, Inc.) recently reported "WhatsApp Contact Discovery Vulnerability Enabling Large-Scale Account Enumeration", a noteworthy cybersecurity incident.

A serious flaw in WhatsApp’s contact discovery feature allowed attackers to verify the existence of up to 3.5 billion WhatsApp accounts through brute-force queries.

The disruption is felt across the environment, affecting WhatsApp Contact Discovery System, and exposing Phone Numbers, Account Existence Status and Potential Profile Metadata (e.g., photos, statuses), with nearly Up to 3.5 billion (theoretical maximum) records at risk.

In response, teams activated the incident response plan, moved swiftly to contain the threat with measures like Codebase Patches to Restrict Contact Query Abuse, and began remediation that includes Implemented Limits on Contact List Uploads and Enhanced Rate-Limiting for Queries, and stakeholders are being briefed through Public Acknowledgment of Vulnerability and Technical Disclosure via Research Collaboration.

The case underscores how Resolved (Vulnerability Patched), teams are taking away lessons such as Phone number–based identity systems inherently lack privacy protections and are vulnerable to enumeration attacks, Convenience features (e.g., contact discovery) can introduce systemic privacy risks if not properly rate-limited or obfuscated and Messaging platforms must balance usability with security, particularly in regions with low cybersecurity awareness, and recommending next steps like Implement **rate-limiting** and **size restrictions** on contact list uploads to prevent brute-force enumeration, Adopt **zero-knowledge proofs** or **private set intersection (PSI)** techniques for contact discovery to minimize metadata exposure and Transition from **raw phone number identifiers** to **hashed or pseudonymous identifiers** to reduce linkage risks, with advisories going out to stakeholders covering Users advised to be cautious of unsolicited messages, even from known platforms and Enterprises encouraged to review identity management practices and limit phone number exposure.

Finally, we try to match the incident with the MITRE ATT&CK framework to see if there is any correlation between the incident and the MITRE ATT&CK framework.

The MITRE ATT&CK framework is a knowledge base of techniques and sub-techniques that are used to describe the tactics and procedures of cyber adversaries. It is a powerful tool for understanding the threat landscape and for developing effective defense strategies.

Rankiteo's analysis has identified several MITRE ATT&CK tactics and techniques associated with this incident, each with varying levels of confidence based on available evidence. Under the Reconnaissance tactic, the analysis identified Active Scanning: Vulnerability Scanning (T1595.002) with moderate to high confidence (85%), supported by evidence indicating exploiting WhatsApp’s server responses to confirm active accounts via brute-force queries, Gather Victim Identity Information: Employee Names (T1589.002) with high confidence (90%), supported by evidence indicating associate phone numbers with user metadata (e.g., profile photos, statuses), and Gather Victim Network Information (T1590) with moderate to high confidence (80%), supported by evidence indicating verify the existence of up to 3.5 billion WhatsApp accounts by uploading massive lists of phone numbers. Under the Resource Development tactic, the analysis identified Obtain Capabilities: Code Signing Certificates (T1588.006) with moderate to high confidence (70%), supported by evidence indicating exploiting WhatsApp’s contact discovery feature to build databases of legitimate users and Acquire Infrastructure: Server (T1583.004) with moderate to high confidence (75%), supported by evidence indicating uploading massive lists of phone numbers implies infrastructure for large-scale queries. Under the Initial Access tactic, the analysis identified Phishing: Spearphishing Link (T1566.002) with high confidence (90%), supported by evidence indicating enable targeted phishing databases and identity-based social engineering. Under the Collection tactic, the analysis identified Automated Collection (T1119) with high confidence (95%), supported by evidence indicating brute-force queries to verify 3.5 billion accounts via contact syncing mechanism. Under the Defense Evasion tactic, the analysis identified Valid Accounts: Cloud Accounts (T1078.004) with moderate to high confidence (70%), supported by evidence indicating exploiting WhatsApp’s contact discovery feature (legitimate service abuse). Under the Impact tactic, the analysis identified Account Access Removal (T1531) with moderate confidence (60%), supported by evidence indicating elevated risk of identity theft due to phone number exposure (potential for account takeover) and Data Destruction (T1485) with moderate confidence (50%), supported by evidence indicating brand reputation impact such as erosion of user trust in privacy protections (indirect). These correlations help security teams understand the attack chain and develop appropriate defensive measures based on the observed tactics and techniques.