CVE-2023-26077: Atera Agent Insecure Permissions Vulnerability

CVE-2023-26077 Overview

CVE-2023-26077 is an insecure permissions vulnerability affecting the Atera Agent through version 1.8.3.6 on Windows systems. The vulnerability occurs when the Atera Agent creates a temporary file in a directory with insecure permissions, potentially allowing local attackers to escalate privileges on the affected system.

Critical Impact

Local attackers with low privileges can exploit insecure temporary file permissions to potentially achieve privilege escalation, compromising the confidentiality, integrity, and availability of the affected Windows system.

Affected Products

• Atera Agent through version 1.8.3.6
• Microsoft Windows (all versions running vulnerable Atera Agent)
• Atera remote monitoring and management (RMM) deployments

Discovery Timeline

• 2023-07-24 - CVE-2023-26077 published to NVD
• 2024-11-21 - Last updated in NVD database

Technical Details for CVE-2023-26077

Vulnerability Analysis

This vulnerability (CWE-276: Incorrect Default Permissions) exists within the Atera Agent's handling of temporary files on Windows systems. When the agent performs certain operations, it creates temporary files in a directory that does not have properly restrictive permissions. This implementation flaw allows local users with limited privileges to potentially access, modify, or replace these temporary files.

The attack requires local access to the system, meaning an attacker must already have some level of access to the Windows machine running the vulnerable Atera Agent. The exploitation does not require user interaction, making it particularly dangerous in multi-user environments or scenarios where an attacker has already gained initial access through other means.

Root Cause

The root cause of CVE-2023-26077 is improper permission configuration when creating temporary files. The Atera Agent fails to set restrictive access control lists (ACLs) on the temporary directory or files it creates, leaving them accessible to other local users. This is a classic example of CWE-276 (Incorrect Default Permissions), where software sets insecure default permissions during file creation operations.

Attack Vector

The attack vector for this vulnerability is local, requiring the attacker to have existing access to the target system. An attacker could exploit this vulnerability through the following attack flow:

1. The attacker gains initial access to a Windows system running the vulnerable Atera Agent
2. The attacker monitors or targets the directory where the Atera Agent creates temporary files
3. Due to insecure permissions, the attacker can read, modify, or replace the temporary files
4. By manipulating these files at the right moment, the attacker can potentially escalate privileges or execute code in the context of the Atera Agent service

The vulnerability can be exploited through techniques such as symlink attacks or file replacement, depending on how the Atera Agent processes the temporary files. For detailed technical information, refer to the GitHub MNDT-2023-0008 Advisory.

Detection Methods for CVE-2023-26077

Indicators of Compromise

• Unusual file creation or modification activity in Atera Agent temporary directories
• Unexpected symbolic links or junction points created in temporary file locations
• File permission changes on Atera Agent-related directories
• Suspicious process activity originating from the Atera Agent installation path

Detection Strategies

• Monitor for file system activity in temporary directories associated with the Atera Agent
• Implement file integrity monitoring on critical Atera Agent directories and files
• Review Windows Security Event logs for privilege escalation attempts (Event IDs 4672, 4673)
• Deploy endpoint detection rules to identify suspicious temporary file manipulation patterns

Monitoring Recommendations

• Configure SentinelOne Singularity to monitor for suspicious file operations in Atera Agent directories
• Enable detailed audit logging for object access on systems running Atera Agent
• Implement behavioral analysis to detect anomalous privilege escalation attempts
• Monitor for unusual process spawning from the Atera Agent service context

How to Mitigate CVE-2023-26077

Immediate Actions Required

• Inventory all systems running Atera Agent and identify vulnerable versions (1.8.3.6 and earlier)
• Prioritize patching on systems with multiple local users or higher risk profiles
• Review and restrict local user access on systems running vulnerable Atera Agent versions
• Implement additional monitoring on affected systems until patches can be applied

Patch Information

Organizations should update the Atera Agent to a version newer than 1.8.3.6 that addresses this vulnerability. Consult the Atera Security Resource for the latest agent version and update instructions. Additionally, review the Mandiant Vulnerability Disclosures repository for detailed technical guidance on this vulnerability.

Workarounds

• Restrict local user access on systems running the vulnerable Atera Agent
• Manually apply restrictive ACLs to temporary directories used by the Atera Agent
• Consider implementing application whitelisting to prevent unauthorized file execution
• Isolate systems running vulnerable versions on network segments with limited access

# Check Atera Agent version on Windows systems
wmic product where "name like '%%Atera%%'" get name,version

# Review permissions on Atera Agent directories
icacls "C:\Program Files\ATERA Networks" /T
icacls "%TEMP%" /T