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Date of Incident:
December 15, 2025
Overview:
In December 2025, SoundCloud experienced a data breach that compromised the personal and contact information of over 29.8 million user accounts. The breach, reported in January 2026, involved unauthorized access through weak API authentication and possibly compromised employee credentials. Attackers targeted the Broadcasting, Media & Internet sector, specifically SoundCloud, and executed extortion attempts using email flooding tactics. Indicators of compromise included Eastern European IP addresses and unusual API access patterns. The incident highlights vulnerabilities in account security and the need for stronger authentication measures.
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Impact:
Personal and contact information of over 29.8 million user accounts including email addresses, geographic locations, names, usernames, and profile statistics were stolen; attackers attempted extortion and harassment via email flooding tactics.
Details:
The SoundCloud Data Breach involved unauthorized access to personal and contact information of over 29.8 million user accounts. The attack vector included exploitation of weak API authentication and possibly compromised employee credentials, aligning with MITRE ATT&CK techniques T1078 (Valid Accounts) and T1531 (Account Access Removal). The attackers executed email flooding harassment tactics as a form of extortion post-breach. Indicators of Compromise (IOCs) include originating IP addresses sourced to Eastern European threat actors, email headers showing high-volume unsolicited traffic, and logs reflecting unusual API access patterns and mass data exfiltration events. Log artifacts showed numerous failed authentication attempts, followed by successful logins from unusual geolocations. Payload analysis revealed automated scripts for data harvesting and mass email dispatch, simulating a Distributed Denial of Service (DDoS) effect against users’ inboxes. Proof-of-concept behavior included API enumeration and token reuse across multiple accounts without multi-factor authentication enforcement.
Remediation:
SoundCloud vendor guidance included immediate revocation and reset of all API keys and tokens, implementation of multi-factor authentication (MFA) for all user and employee accounts, and tightening of rate limits on API calls to mitigate abuse. Temporary mitigations advised included monitoring outgoing email traffic for spam patterns and alerting for unusual OAuth token activities. Known workaround involved users resetting passwords and enabling MFA on their accounts promptly.
Takeaway for CISO:
This breach highlights the critical importance of securing API endpoints and enforcing strong access controls including MFA, especially for platforms handling large user data volumes. CISOs must prioritize rapid detection capabilities for unusual access and exfiltration attempts across APIs and implement robust incident response plans focusing on data privacy compliance and user trust restoration.Outpace Attackers With AI-Based Automate Penetration Testing With FireCompass:
