Azure Key Vault Security Flaw: Risks Post-Entra ID Compromise

Microsoft’s Azure Key Vault, the supposedly impenetrable fortress guarding your encryption keys, secrets, and certificates, may have a gaping security flaw that attackers can exploit post-compromise of Entra ID (formerly known as Azure AD). The implications here are colossal: imagine unauthorized parties using this vulnerability to unlock sensitive data stored in your cloud infrastructure.
In a cybersecurity exposé, concerns around these vulnerabilities were highlighted, showing how access policies in Azure Key Vault could be manipulated when an attacker gains just one thing—compromised Entra ID credentials. The details are chilling, starting with the deepest dive into an attacker’s playbook and ending with a call to arms for organizations to bolster their cloud defenses.
Let’s dissect the attack avenue, the technical breakdown of how this happens, and the concrete steps you can take to defend yourself.

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The Anatomy of the Exploit​

Compromising Entra ID​

The foothold that attackers look for begins with a breached set of Entra ID credentials. Whether achieved through phishing, brute force, token theft, or credential stuffing, compromised credentials act as a master key for attackers to infiltrate an organization’s Azure infrastructure. Once an attacker has these credentials, they need only the right set of tools—and oh boy, are there tools.

Gaining Tokenized Access​

As part of the manipulation, tools like PowerShell and Azure CLI come into play. Here’s a breakdown of how attackers proceed:

• Login Using PowerShell:
  Attackers authenticate with the compromised credentials using commands like:
  

  powershell
  
     $passwd = ConvertTo-SecureString "<password>" -AsPlainText -Force
  
     $creds = New-Object System.Management.Automation.PSCredential("<user_email>", $passwd)
  
     Connect-AzAccount -Credential $creds

• Acquire Tokens for Azure Resources:
  Tokens, the lifeblood of access in cloud environments, are gathered using the Get-AzAccessToken cmdlet. These tokens are essential for interacting with Azure APIs and resources.
• Enumerate Resources:
  With access tokens in hand, attackers can enumerate the resources with the Get-AzResource command, which flags all accessible Azure assets, including the coveted Key Vaults.

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Breaking into Key Vaults​

Now that the attacker sees your Azure Key Vault sitting there shiny and tempting, further steps strip away security layers like peeling off the wrapping of a forbidden candy bar.

Testing Permissions​

Command-line tools like Get-AzKeyVaultSecret and API requests to Key Vault endpoints help attackers gauge their permissions. Think of it as knocking on the doors of the treasure chest to see which ones creak open.

Enumerating Keys​

After assessing the playing field, the attacker now has a laser focus. Commands like Get-AzKeyVaultKey provide critical information about cryptographic keys stored in the Key Vault. Metadata such as key types, algorithms, and versions are revealed—a roadmap for the attacker’s next steps.

Decrypting Data​

Here’s where the exploit gets sinister. Using tools like Invoke-AzKeyVaultKeyOperation, attackers orchestrate decryption operations. For example:

$encryptedBytes = [Convert]::FromBase64String('<Base64 string>')
$DecryptedData = Invoke-AzKeyVaultKeyOperation -Operation Decrypt -Algorithm RSA1_5 -ByteArrayValue $encryptedBytes -VaultName <vault_name> -Name <key_name>
This simple yet devastating command sequence is like having the Key Vault spit out the secrets its creators meant to protect. All it took was a combination of compromised credentials and improperly configured access policies.
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[HEADING=1][B]Burp Suite in the Mix[/B][/HEADING]
For those familiar with penetration testing, the role of Burp Suite in this attack cannot be ignored. Burp reveals the traffic sent to Azure’s APIs. The tool logs requests to endpoints such as [ICODE]/decrypt[/ICODE] containing Base64 content and responses bearing decrypted output. In the wrong hands, tools like Burp Suite are the equivalent of a magnifying glass for security loopholes.
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[HEADING=1][B]Mitigation: Fortifying the Azure Bastion[/B][/HEADING]
If this story hasn’t got you double-checking your Azure configurations, nothing will. The threat is real, but so are the defenses! Here’s what organizations should do immediately:
[HEADING=1]1. [B]Restrict Key Vault Permissions[/B][/HEADING]
Apply the principle of [B]least privilege[/B]. Limit permissions to only those users and services that absolutely need them. Ensure no permissions allow decryption capabilities unless absolutely necessary.
[HEADING=1]2. [B]Enable Managed Identities[/B][/HEADING]
Static credentials have a nasty habit of getting leaked or stolen. By using Managed Identities, you take humans out of the equation, minimizing attack vectors.
[HEADING=1]3. [B]Audit Activity Logs[/B][/HEADING]
Turn on Azure logging and pay special attention to POST requests sent to [ICODE]/decrypt[/ICODE] endpoints or other high-risk API endpoints. It’s also crucial to enable security alerts to flag suspicious behavior immediately.
[HEADING=1]4. [B]Conditional Access Policies[/B][/HEADING]
Limit access to trusted IP addresses or known geographies with Conditional Access. This can significantly reduce the risk of credential misuse from unknown locations.
[HEADING=1]5. [B]Regularly Review Key Vault Policies[/B][/HEADING]
Every few months (or weeks, depending on how paranoid you are), review access policies for the Key Vault. Ensure only current, authorized systems and personnel are listed. Revoke permissions wherever suitable and rotate sensitive keys periodically.
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[HEADING=1][B]What’s the Bigger Picture?[/B][/HEADING]
The exploitability of Azure Key Vault underscores a broader truth—we are often our own worst enemy when it comes to cloud security. Misconfigured access policies, combined with compromised credentials, open the floodgates to cyberattacks. But the solution lies in vigilance.
Cloud infrastructure isn’t “set it and forget it.” Between shifting attack strategies and increasingly sophisticated tools available to cybercriminals, treating cloud security as a one-off exercise is a recipe for disaster. Organizations must continuously evaluate, refine, and harden their defenses.
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[HEADING=1][B]Final Word[/B][/HEADING]
The demonstrated weaknesses of Azure Key Vault after a breach of Entra ID showcase how small oversights can lead to catastrophic consequences. Securing your cloud environment might feel like a Herculean task, but the tools and practices exist; it’s about using them wisely.
What’s your take—are we doing enough to secure our cloud environments, or is the industry still lagging behind? Share your thoughts and experiences in the comments on WindowsForum.com! Let’s discuss this critical vulnerability together.
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[B]Source:[/B] CybersecurityNews [url="https://cybersecuritynews.com/azure-key-vault-vulnerabilities-could-leak-sensitive-data-after-entra-id-breach/"]https://cybersecuritynews.com/azure-key-vault-vulnerabilities-could-leak-sensitive-data-after-entra-id-breach/[/url]