CVE-2024-35276: Fortinet FortiAnalyzer Buffer Overflow

CVE-2024-35276 Overview

A stack-based buffer overflow vulnerability has been identified in multiple Fortinet products, including FortiAnalyzer, FortiManager, and their cloud variants. This vulnerability allows remote attackers to execute unauthorized code or commands by sending specially crafted packets to vulnerable systems. Given the critical role these products play in enterprise security management and log analysis, successful exploitation could have severe consequences for organizational security posture.

Critical Impact

This stack-based buffer overflow enables remote code execution without authentication, potentially allowing attackers to gain complete control over FortiAnalyzer and FortiManager systems used for centralized security management.

Affected Products

• Fortinet FortiAnalyzer versions 7.4.0 through 7.4.3, 7.2.0 through 7.2.5, 7.0.0 through 7.0.12, 6.4.0 through 6.4.14
• Fortinet FortiManager versions 7.4.0 through 7.4.3, 7.2.0 through 7.2.5, 7.0.0 through 7.0.12, 6.4.0 through 6.4.14
• Fortinet FortiManager Cloud versions 7.4.1 through 7.4.3, 7.2.1 through 7.2.5, 7.0.1 through 7.0.11, 6.4.1 through 6.4.7
• Fortinet FortiAnalyzer Cloud versions 7.4.1 through 7.4.3, 7.2.1 through 7.2.5, 7.0.1 through 7.0.11, 6.4.1 through 6.4.7

Discovery Timeline

• 2025-01-14 - CVE-2024-35276 published to NVD
• 2025-01-31 - Last updated in NVD database

Technical Details for CVE-2024-35276

Vulnerability Analysis

This vulnerability is classified as CWE-121 (Stack-based Buffer Overflow) and CWE-787 (Out-of-bounds Write). The flaw exists in the packet processing functionality of the affected Fortinet products. When the vulnerable components receive specially crafted network packets, insufficient boundary checking allows data to overflow the allocated stack buffer. This overflow corrupts adjacent memory, including the function return address, enabling attackers to redirect program execution to malicious code.

FortiAnalyzer and FortiManager are centralized management and logging platforms used to manage Fortinet security infrastructure across enterprise environments. Compromise of these systems could provide attackers with visibility into security configurations, logging data, and potentially lateral access to managed FortiGate devices.

Root Cause

The root cause of this vulnerability is improper validation of input length when processing incoming network packets. The affected code fails to verify that user-supplied data does not exceed the size of the destination buffer on the stack. This missing bounds check allows an attacker to write beyond the allocated buffer space, overwriting critical stack structures including saved return addresses and frame pointers.

Attack Vector

The vulnerability is exploitable over the network without requiring authentication or user interaction. An attacker can send maliciously crafted packets to the vulnerable service, triggering the buffer overflow condition. The attack can be executed remotely against any exposed FortiAnalyzer or FortiManager instance running a vulnerable version.

The exploitation process involves:

1. Identifying a vulnerable FortiAnalyzer or FortiManager instance accessible over the network
2. Crafting a network packet containing payload data exceeding the expected buffer size
3. Sending the malicious packet to the target, causing the stack buffer to overflow
4. Overwriting the return address to redirect execution to attacker-controlled code
5. Achieving remote code execution with the privileges of the vulnerable process

Due to the sensitive nature of this vulnerability, specific exploitation code has not been included. For technical details, refer to the Fortinet Security Advisory FG-IR-24-165.

Detection Methods for CVE-2024-35276

Indicators of Compromise

• Unusual network traffic patterns or malformed packets targeting FortiAnalyzer or FortiManager management interfaces
• Unexpected process crashes or service restarts on FortiAnalyzer or FortiManager systems
• Anomalous outbound connections from management appliances to unknown external IP addresses
• Unauthorized configuration changes or new administrator accounts on managed devices

Detection Strategies

• Implement network intrusion detection signatures to identify malformed packets targeting Fortinet management services
• Monitor FortiAnalyzer and FortiManager system logs for unexpected crashes, segmentation faults, or memory access violations
• Deploy endpoint detection solutions to identify anomalous process behavior or shellcode execution on management systems
• Review authentication logs for unauthorized access attempts or suspicious administrative activity

Monitoring Recommendations

• Enable verbose logging on FortiAnalyzer and FortiManager systems and forward logs to a separate SIEM for analysis
• Implement network segmentation to restrict access to management interfaces and monitor inter-segment traffic
• Configure alerting for any service interruptions or unexpected restarts of critical Fortinet management services
• Regularly audit system integrity and compare configurations against known-good baselines

How to Mitigate CVE-2024-35276

Immediate Actions Required

• Identify all FortiAnalyzer, FortiManager, and their cloud variants in your environment and determine their version numbers
• Apply the appropriate security patches from Fortinet immediately for all affected systems
• Restrict network access to FortiAnalyzer and FortiManager management interfaces to trusted IP addresses only
• Implement network segmentation to isolate management infrastructure from general network traffic
• Monitor affected systems for signs of compromise while patches are being deployed

Patch Information

Fortinet has released security updates addressing this vulnerability. Organizations should upgrade to the following versions or later to remediate CVE-2024-35276:

• FortiAnalyzer: Upgrade to 7.4.4 or later, 7.2.6 or later, 7.0.13 or later, or 6.4.15 or later
• FortiManager: Upgrade to 7.4.4 or later, 7.2.6 or later, 7.0.13 or later, or 6.4.15 or later
• FortiManager Cloud and FortiAnalyzer Cloud: Contact Fortinet or check the cloud service for automatic updates

For detailed patch information and download links, refer to the Fortinet Security Advisory FG-IR-24-165.

Workarounds

• Restrict management interface access using firewall rules to allow connections only from trusted administrator workstations
• Implement VPN requirements for remote management access to FortiAnalyzer and FortiManager systems
• Deploy web application firewalls or intrusion prevention systems in front of management interfaces to filter malicious traffic
• Disable any unnecessary network services on affected systems to reduce the attack surface

# Example: Restrict management access to specific trusted networks
# On FortiAnalyzer/FortiManager CLI:
config system interface
    edit "mgmt"
        set allowaccess ping https ssh
        set trust-ip-1 192.168.1.0/24
        set trust-ip-2 10.0.0.0/8
    next
end