Security Breach Exposes Vulnerabilities in Azure Key Vault Access Policies
In a recent analysis, cybersecurity professionals uncovered significant vulnerabilities associated with Azure Key Vault’s access policies following the compromise of Entra ID (formerly Azure Active Directory) credentials. The detailed walkthrough illustrates how attackers can manipulate these access policies to retrieve sensitive information, raising alarms over the security measures currently in place within cloud environments.
The report published by penetration tester Faran Siddiqui highlights a specific scenario dubbed "Key Vault 06 – Abuse Decryption Key." This case provides a stark reminder of the potential threats within the Azure ecosystem and sheds light on techniques that involve the AzureAD Command-Line Interface (CLI) and Microsoft Graph API. The investigative work aims to equip red team testers and penetration specialists with an understanding of the risks that loom over enterprises utilizing Azure Key Vault.
At the center of this breach is the exploitation of compromised credentials and gaps in the established access protocols. Cyber adversaries capable of accessing Azure accounts can potentially retrieve a host of sensitive information, including encryption keys and secrets. The analysis demonstrates how tools such as Burp Suite can be instrumental in monitoring interactions with Azure endpoints, essential for understanding the attack vectors employed.
This particular attack cycle begins with the attacker gaining initial access through compromised Azure credentials, which can be exploited using PowerShell commands to authenticate into the Azure environment. Once logged in, the attacker can connect to the Microsoft Graph API and enumerate available resources, which likely involves the initial access and enumeration tactics outlined in the MITRE ATT&CK framework.
In one method, the attacker runs a sequence of PowerShell commands to establish connections and enumerate resources. Utilizing the Get-AzResource command, the attacker can uncover a myriad of accessible resources, including Azure Key Vaults. By sending a GET request to the management endpoint, data is returned in JSON format that identifies the key vault’s name, laying the groundwork for further exploitation.
Despite attempts to list secrets stored within the Key Vault, the compromised account initially encounters permission restrictions. However, the attacker can pivot to enumerating the cryptographic keys within the vault, utilizing commands to extract key details and metadata about stored cryptographic keys. This process signifies the tactics of persistence and privilege escalation as the attacker maneuvers through various levels of access.
Once access to at least one RSA key is established, the decryption capabilities of the Azure Key Vault become critical for the attacker’s success. The process involves leveraging a provided decryption key to convert encrypted Base64 strings into readable text. Through series of structured commands, the adversary successfully decrypts sensitive information, highlighting the severe implications of inadequate access controls.
Burp Suite’s logging reveals the usage of POST requests to specific endpoints, facilitating the decryption process. This exposure illustrates potential security oversights in access policy configurations, emphasizing the consequences of reliance on compromised credentials. The investigation underlines the critical need for robust Role-Based Access Control (RBAC) implementations and the importance of regular audits of Azure activity logs to detect suspicious activities.
As businesses increasingly migrate to the cloud, this incident serves as a reminder of the vulnerabilities inherent in Azure Key Vaults, necessitating comprehensive security measures to mitigate risks. The analysis urges organizations to adopt a continuous security posture, recognizing that the ease with which access policies can be compromised poses serious threats to sensitive data stored in cloud environments.
Stakeholders are encouraged to take proactive measures by restricting access permissions, enabling Managed Identities for enhanced security, auditing logs for unusual activity, implementing Conditional Access Policies, and regularly reviewing key vault configurations. By reinforcing security protocols, organizations can better protect their assets and minimize exposure to such devastating attacks.
