CVE-2022-39327: Azure CLI RCE Vulnerability

CVE-2022-39327 Overview

CVE-2022-39327 is a critical command injection vulnerability affecting Microsoft Azure Command-Line Interface (Azure CLI) versions prior to 2.40.0. This vulnerability enables potential code injection when Azure CLI commands are executed on Windows machines using PowerShell, particularly in scenarios where parameter values are sourced from external inputs containing shell metacharacters (& or |).

Critical Impact

Attackers can inject and execute arbitrary commands on vulnerable Windows systems running Azure CLI when external input containing shell metacharacters is passed as command parameters.

Affected Products

• Microsoft Azure Command-Line Interface versions prior to 2.40.0
• Microsoft Windows (all versions when running vulnerable Azure CLI)
• PowerShell (all versions in combination with vulnerable Azure CLI)

Discovery Timeline

• 2022-10-25 - CVE-2022-39327 published to NVD
• 2024-11-21 - Last updated in NVD database

Technical Details for CVE-2022-39327

Vulnerability Analysis

This vulnerability stems from improper handling of shell metacharacters in parameter values passed to Azure CLI commands. When Azure CLI runs on Windows systems with PowerShell, the application fails to adequately sanitize input containing the ampersand (&) or pipe (|) characters. These characters have special meaning in Windows command shells, where & allows command chaining and | enables piping output between commands.

The vulnerability is particularly dangerous in automation scenarios where Azure CLI commands process parameters from external sources such as user input, environment variables, or data from external APIs. An attacker who can influence these parameter values can inject malicious commands that execute with the privileges of the Azure CLI process.

The weakness falls under CWE-94 (Improper Control of Generation of Code - Code Injection) and CWE-78 (Improper Neutralization of Special Elements used in an OS Command - OS Command Injection).

Root Cause

The root cause is insufficient input validation and sanitization of command-line parameters before they are processed by the underlying Windows shell. Azure CLI failed to properly escape or reject shell metacharacters in user-controllable input, allowing the shell to interpret these characters as command delimiters rather than literal string content.

Attack Vector

The attack vector is network-based, requiring no authentication and no user interaction. An attacker can exploit this vulnerability remotely by providing malicious input to applications that incorporate user-controlled data into Azure CLI commands. The attack requires:

1. The target system running Azure CLI on Windows
2. Any version of PowerShell present on the system
3. A parameter value containing & or | characters being processed

For example, if an application accepts a resource name from user input and passes it to an Azure CLI command, an attacker could supply a value like legitname & malicious-command to chain arbitrary command execution.

Detection Methods for CVE-2022-39327

Indicators of Compromise

• Unexpected Azure CLI command executions with unusual parameter patterns containing & or | characters
• PowerShell process spawning unexpected child processes after Azure CLI invocations
• Anomalous command sequences in Windows Event logs showing command chaining patterns
• Unusual network connections or file system modifications following Azure CLI operations

Detection Strategies

• Monitor Windows Event logs for suspicious command-line patterns containing shell metacharacters in Azure CLI invocations
• Implement application-level logging to capture Azure CLI command parameters before execution
• Deploy endpoint detection rules to identify command injection patterns in PowerShell processes
• Audit scripts and automation workflows that pass external input to Azure CLI commands

Monitoring Recommendations

• Enable enhanced command-line process auditing in Windows Security policies
• Configure SIEM alerts for Azure CLI processes spawning unexpected child processes
• Review Azure CLI command history and correlate with application logs for anomalies
• Implement input validation monitoring at the application layer before Azure CLI invocation

How to Mitigate CVE-2022-39327

Immediate Actions Required

• Upgrade Azure CLI to version 2.40.0 or later immediately
• Audit all automation scripts and applications that invoke Azure CLI with external input
• Implement strict input validation to reject or escape & and | characters in parameter values
• Review and restrict permissions for accounts running Azure CLI commands

Patch Information

Microsoft has addressed this vulnerability in Azure CLI version 2.40.0. The fix implements proper sanitization of shell metacharacters in command parameters. Details of the remediation can be found in GitHub Pull Request #23514 and GitHub Pull Request #24015. The complete security advisory is available at GitHub Security Advisory GHSA-47xc-9rr2-q7p4.

Workarounds

• Implement application-level input validation to strip or escape & and | characters before passing to Azure CLI
• Run Azure CLI in isolated environments with restricted network access and minimal privileges
• Consider running Azure CLI in non-Windows environments (Linux/macOS) where this specific vulnerability does not apply
• Use Azure SDK libraries directly instead of CLI commands when processing untrusted input

# Verify Azure CLI version and upgrade if necessary
az --version

# Upgrade Azure CLI on Windows using MSI installer
# Download latest version from https://aka.ms/installazurecliwindows

# Or upgrade using pip if installed via pip
pip install --upgrade azure-cli

# Verify updated version is 2.40.0 or later
az --version | Select-String "azure-cli"