Cisco experienced a cyberattack after malicious actors leveraged stolen credentials from the recent Trivy supply chain vulnerability to penetrate its internal development network and exfiltrate source code belonging to both Cisco and its clients.

An anonymous source revealed to BleepingComputer that Cisco’s Unified Intelligence Center, CSIRT, and EOC teams addressed the intrusion, which involved a harmful “GitHub Action plugin” originating from the recent Trivy compromise.

The attackers exploited the malicious GitHub Action to exfiltrate credentials and data from Cisco’s build and development environment, affecting numerous devices including some workstations used by developers and in labs.

While the initial intrusion is contained, BleepingComputer learned that Cisco anticipates ongoing repercussions from subsequent LiteLLM and Checkmarx supply chain attacks.

Reportedly, the breach resulted in the theft of multiple AWS keys, which were subsequently used for unauthorized activities across a limited number of Cisco AWS accounts. Cisco has isolated compromised systems, begun re-imaging them, and is implementing a large-scale credential reset.

BleepingComputer has discovered that over 300 GitHub repositories were cloned during the incident, including source code for AI-driven products like AI Assistants, AI Defense, and products that are still under development.

A portion of the stolen code repositories are said to belong to Cisco’s corporate customers, including banks, BPOs, and governmental bodies in the United States.

BleepingComputer was told by multiple sources that the Cisco CI/CD and AWS account breaches were carried out by more than one malicious actor, each exhibiting different levels of involvement.

BleepingComputer reached out to Cisco for comment on the breach but has yet to receive a response to our inquiries.

Cisco’s breach was triggered by this month’s Trivy vulnerability scanner supply chain attack, wherein malicious actors compromised the GitHub pipeline of the project to propagate malware designed to steal credentials via official releases and GitHub Actions.

This attack facilitated the theft of CI/CD credentials from organizations employing the tool, granting attackers access to thousands of internal build environments.

Security researchers have connected these supply chain attacks to the TeamPCP threat group due to their utilization of the “TeamPCP Cloud Stealer” information stealer. TeamPCP has been orchestrating a series of supply chain attacks aimed at developer code platforms, including GitHub, PyPi, NPM, and Docker.

The group also compromised the LiteLLM PyPI package, impacting tens of thousands of devices, and the Checkmarx KICS project, to deploy the same information-stealing malware.