CVE-2023-0977: Trellix Agent DOS Vulnerability

CVE-2023-0977 Overview

CVE-2023-0977 is a heap-based overflow vulnerability affecting Trellix Agent on both Windows and Linux platforms. The vulnerability exists in versions 5.7.8 and earlier, allowing a remote authenticated user to alter the page heap in the macmnsvc process memory block. Successful exploitation results in the service becoming unavailable, causing a denial of service condition.

Critical Impact

Remote attackers with low privileges can exploit this heap overflow to crash the Trellix Agent service, disrupting endpoint security monitoring and protection capabilities across affected systems.

Affected Products

• Trellix Agent version 5.7.8 and earlier (Windows)
• Trellix Agent version 5.7.8 and earlier (Linux)
• Systems running Linux Kernel with vulnerable Trellix Agent installations
• Systems running Microsoft Windows with vulnerable Trellix Agent installations

Discovery Timeline

• 2023-04-03 - CVE-2023-0977 published to NVD
• 2024-11-21 - Last updated in NVD database

Technical Details for CVE-2023-0977

Vulnerability Analysis

This vulnerability is classified as a heap-based buffer overflow (CWE-787: Out-of-bounds Write, CWE-120: Buffer Copy without Checking Size of Input). The flaw resides in the macmnsvc process, which is a core service component of the Trellix Agent responsible for endpoint management and communication functions.

The vulnerability allows a remote authenticated attacker to manipulate the heap memory allocation within the macmnsvc process. By sending specially crafted input to the service, an attacker can overflow the allocated heap buffer, corrupting adjacent memory structures. This memory corruption disrupts the normal operation of the service, leading to a crash and subsequent denial of service.

The attack requires network access and low-level privileges, meaning the attacker must have some form of authenticated access to the target system or network. While the vulnerability does not directly enable code execution or data exfiltration, the availability impact is significant as it can disable endpoint security protections.

Root Cause

The root cause of CVE-2023-0977 is improper bounds checking during buffer copy operations within the macmnsvc process. When processing incoming data, the service fails to adequately validate the size of input before copying it into a fixed-size heap buffer. This classic buffer overflow condition (CWE-120) allows data to be written beyond the allocated memory region, corrupting the heap structure and destabilizing the process.

Attack Vector

The attack is network-based, allowing remote exploitation without requiring physical access to the target system. An attacker with low-privilege network access can send maliciously crafted requests to the Trellix Agent service. The attack does not require user interaction, making it suitable for automated exploitation scenarios.

The exploitation flow involves:

1. Establishing a network connection to the vulnerable Trellix Agent service
2. Authenticating with low-privilege credentials
3. Sending specially crafted payloads designed to overflow the heap buffer in macmnsvc
4. The overflow corrupts heap metadata and adjacent memory structures
5. The macmnsvc process crashes, resulting in denial of service

No public exploit code or proof-of-concept is currently available for this vulnerability. For detailed technical specifications, refer to the Trellix Security Advisory SB10396.

Detection Methods for CVE-2023-0977

Indicators of Compromise

• Unexpected crashes or restarts of the macmnsvc process on Trellix Agent installations
• Abnormal memory consumption patterns in the Trellix Agent service prior to crashes
• Network traffic anomalies targeting Trellix Agent communication ports
• Event log entries indicating heap corruption or access violation errors in macmnsvc

Detection Strategies

• Monitor process stability and crash events for macmnsvc service across all endpoints running Trellix Agent
• Implement network intrusion detection rules to identify anomalous traffic patterns targeting Trellix Agent services
• Deploy endpoint detection and response (EDR) solutions like SentinelOne to detect heap corruption attempts and abnormal process behavior
• Review Windows Event Logs and Linux system logs for application crash events related to Trellix Agent components

Monitoring Recommendations

• Configure alerting for repeated macmnsvc process failures or service restarts
• Establish baseline network traffic patterns for Trellix Agent communications to identify deviations
• Enable verbose logging on Trellix Agent installations to capture detailed diagnostic information during incidents
• Implement centralized log collection to correlate potential attack attempts across multiple endpoints

How to Mitigate CVE-2023-0977

Immediate Actions Required

• Identify all systems running Trellix Agent version 5.7.8 or earlier across both Windows and Linux environments
• Prioritize patching for internet-facing and critical infrastructure systems
• Apply the security update provided by Trellix as documented in Security Advisory SB10396
• Review network access controls to limit unauthorized connections to Trellix Agent services

Patch Information

Trellix has released a security update to address this vulnerability. Organizations should upgrade to the latest version of Trellix Agent that contains the fix for CVE-2023-0977. Detailed patch information and download instructions are available in the Trellix Security Advisory SB10396.

Workarounds

• Restrict network access to Trellix Agent services using firewall rules to limit exposure to trusted networks only
• Implement network segmentation to isolate systems running vulnerable Trellix Agent versions from untrusted network segments
• Monitor and alert on macmnsvc process crashes as an interim detection measure until patching is complete
• Consider temporarily disabling non-essential Trellix Agent network services if immediate patching is not feasible

# Example: Restrict network access to Trellix Agent services (Windows Firewall)
netsh advfirewall firewall add rule name="Block External Trellix Agent Access" dir=in action=block protocol=tcp localport=<trellix_port> remoteip=any

# Example: Linux iptables rule to restrict access
iptables -A INPUT -p tcp --dport <trellix_port> -s ! 10.0.0.0/8 -j DROP