Malicious Python Packages on PyPI: A Silent Threat Lurking in Social Media API Exploits

The threat landscape in cybersecurity continues to evolve in unexpected and subtle ways. A recent wave of Python packages uploaded to the Python Package Index (PyPI) has revealed a sophisticated method cybercriminals are now using to validate stolen social media account credentials quietly, and at scale.

Security analysts have flagged three malicious packages checker-SaGaF, steinlurks, and sinnercore that automate the process of checking whether usernames and emails are tied to active TikTok and Instagram accounts. What makes this alarming isn't just the fact that these packages exist, but the stealthy precision with which they operate.

These packages were released over a span of two years, from April 2023 to March 2025, allowing threat actors to slip under the radar while posing a significant risk to the software supply chain. By abusing private API endpoints, the packages are capable of confirming the existence of accounts. This validation sets the stage for a much darker series of events from credential stuffing and password spraying to the resale of verified credentials on underground markets.

Anatomy of a Breach: What These Packages Do

• checker-SaGaF targets TikTok and Instagram’s password recovery APIs. By mimicking the behavior of official apps and injecting forged payloads, it can trigger platform responses that reveal whether an email is tied to an existing account.
• Steinlurks randomizes HTTP headers and cycles through multiple API endpoints to avoid detection. This kind of evasion makes it harder for traditional security tools to flag suspicious activity.
• sinnercore goes further launching password reset requests on Instagram using deprecated endpoints. While this may seem obsolete, it still provokes interaction, potentially harassing users and collecting valuable metadata.

For just a few hundred dollars, cybercriminals can buy tens of thousands of verified email addresses at a fraction of a cent per victim. At scale, this enables follow-up campaigns ranging from phishing and doxxing to more destructive social engineering exploits.

The Core of the Threat: API Exploitation

What makes this tactic so effective is its quiet exploitation of what many developers overlook: verbose error messages and overly generous APIs. These systems are often built for usability, but in the hands of bad actors, they become vectors of information leakage.

Validated credentials are the first domino in an attack chain that can spiral into serious incidents including operational disruption, data breaches, and reputational damage.

Defending Against the Unseen

As attackers adapt and pivot to API abuse and open-source software manipulation, organizations must also evolve:

• Developers must audit APIs for excessive information leakage and apply rate limiting rigorously.
• Security teams should monitor dependency trees in real time using tools like Socket or Snyk.
• Regular credential hygiene and account activity monitoring should be prioritized, especially in sectors where account access equates to access to critical systems.

Conclusion

The face of cybercrime is growing more subtle and automated. These malicious packages are not just isolated experiments they are glimpses into a future where account reconnaissance is commoditized and scalable. The longer these threats remain unnoticed, the wider their reach becomes.

Organizations that rely on social media platforms for marketing, outreach, or customer support especially in the retail, financial, government, healthcare, and manufacturing sectors should be on alert. The battleground has shifted. It’s no longer just about breaches, it's about silent validation and strategic exploitation.

About COE Security

COE Security partners with organizations in financial services, healthcare, retail, manufacturing, and government to secure AI-powered systems and ensure compliance. Our offerings include:

• AI-enhanced threat detection and real-time monitoring
• Data governance aligned with GDPR, HIPAA, and PCI DSS
• Secure model validation to guard against adversarial attacks
• Customized training to embed AI security best practices
• Penetration Testing (Mobile, Web, AI, Product, IoT, Network & Cloud)
• Secure Software Development Consulting (SSDLC)
• Customized CyberSecurity Services

We also help organizations detect malicious packages in their development pipelines, audit API designs for overexposure, and prepare for advanced social engineering threats that spread rapidly once access is confirmed. Our team can help your developers harden systems against subtle, supply-chain driven intrusions.

Follow COE Security on LinkedIn for ongoing insights into safe, compliant AI adoption, cutting-edge threat intelligence, and real-world cyber defense strategies.

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