The European Union's Cybersecurity Service (CERT-EU) has attributed the European Commission cloud hack to the TeamPCP threat group, saying the resulting breach exposed the data of at least 29 other Union entities.

The European Commission publicly disclosed the incident on March 27 after BleepingComputer reached out for confirmation that the Amazon cloud environment of the European Union's main executive body had been breached.

Two days earlier, the Commission notified CERT-EU of the hack, saying that its Cybersecurity Operations Center was not alerted to API misuse, potential account compromise, or any abnormal network traffic until March 24, five days after the initial intrusion.

On March 10, TeamPCP used a compromised Amazon Web Services API key with management rights over other European Commission AWS accounts (stolen in the Trivy supply-chain attack) to breach the Commission's Amazon cloud environment.

In the next stage of the attack, they used TruffleHog (a tool for scanning and validating cloud credentials) to search for additional secrets, then attached a newly created access key to an existing user to evade detection before conducting further reconnaissance and stealing data.

TeamPCP has been linked to supply-chain attacks targeting multiple other developer code platforms, such as GitHub, PyPi, NPM, and Docker.

The cybercrime gang has also compromised the LiteLLM PyPI package in an attack that impacted tens of thousands of devices using its "TeamPCP Cloud Stealer" information-stealing malware.

Data leaked on the dark web by ShinyHunters

On March 28, data extortion group ShinyHunters published the stolen dataset on their dark web leak site as a 90GB archive of documents (approximately 340GB uncompressed), containing names, email addresses, and email content.

CERT-EU's analysis confirmed that the threat actors have stolen tens of thousands of files containing personal information, usernames, email addresses, and email content, and that the resulting data breach potentially affects 42 internal European Commission clients and at least 29 other Union entities using the europa.eu web hosting service.

"The threat actor used the compromised AWS secret to exfiltrate data from the affected cloud environment. The exfiltrated data relates to websites hosted for up to 71 clients of the Europa web hosting service: 42 internal clients of the European Commission, and at least 29 other Union entities," CERT-EU said on Thursday.

"Analysis of the published dataset has so far confirmed the presence of personal data, including lists of names, last names, usernames, and email addresses, predominantly from the European Commission’s websites but potentially pertaining to users across multiple Union entities," it added.

"The dataset also contains at least 51,992 files related to outbound email communications, totalling 2.22 GB. The majority of these are automated notifications with little to no content. However, 'bounce-back' notifications, which are responses to incoming messages from users, may contain the original user-submitted content, posing a risk of personal data exposure."

CERT-EU added that no websites were taken offline as a result of this incident or tampered with, and no lateral movement to other Commission AWS accounts has been detected.

While the analysis of exfiltrated databases and files is ongoing and will likely require "a considerable amount of time," the Commission has notified relevant data protection authorities and is in direct communication with affected entities.

In February, the European Commission disclosed another data breach after discovering that a mobile device management platform used to manage staff's devices had been hacked.