CVE-2019-0804 in Azure Linux Guest Agent
Summary
by MITRE
An information disclosure vulnerability exists in the way Azure WaLinuxAgent creates swap files on resource disks, aka 'Azure Linux Agent Information Disclosure Vulnerability'.
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Analysis
by VulDB Data Team • 08/27/2023
The CVE-2019-0804 vulnerability represents a critical information disclosure flaw within Microsoft Azure's Windows Azure Linux Agent implementation. This vulnerability specifically affects how the agent handles swap file creation on resource disks within Azure virtual machine environments. The flaw arises from improper handling of temporary file creation processes that occur during the initialization of swap space on ephemeral storage volumes. The vulnerability impacts Azure Linux virtual machines that utilize resource disks for temporary storage and swap file operations, potentially exposing sensitive information through the swap file creation mechanism.
The technical root cause of this vulnerability stems from the Azure Linux Agent's insufficient sanitization of swap file creation processes on resource disks. When the agent initializes swap space on resource disks, it creates temporary files that contain metadata about the virtual machine environment, including instance identifiers, network configuration details, and potentially other sensitive operational data. The vulnerability manifests when these temporary files are not properly secured or cleaned up, allowing unauthorized access to information that should remain confidential within the Azure environment. This flaw operates at the system level where the agent's file handling routines fail to implement proper access controls or secure deletion practices for temporary swap file components.
The operational impact of CVE-2019-0804 extends beyond simple information disclosure, creating potential attack vectors for adversaries seeking to enumerate Azure infrastructure components. An attacker who gains access to the resource disk or can execute code on the target system could potentially extract sensitive information from improperly secured swap file components, including virtual machine metadata, network configuration details, and potentially credential information. This vulnerability aligns with CWE-200, which addresses information exposure issues, and represents a significant concern for cloud security posture management. The impact is particularly severe in multi-tenant Azure environments where information leakage could enable attackers to perform reconnaissance activities against other tenants or service components within the same infrastructure.
Mitigation strategies for CVE-2019-0804 require immediate implementation of Azure Linux Agent updates to address the swap file creation process security flaws. Organizations should ensure all Azure virtual machines running Linux are updated to versions of the Azure Linux Agent that properly handle swap file creation and temporary file management. System administrators should also implement monitoring controls to detect unauthorized access to resource disk contents and establish proper file permissions for swap file components. The vulnerability demonstrates the importance of secure temporary file handling practices and aligns with ATT&CK technique T1082, which covers system information discovery, as attackers could leverage this information to better understand the target environment. Additionally, implementing network segmentation and access controls for resource disks can provide additional defense-in-depth measures against exploitation attempts targeting this vulnerability.