CVE-2024-26010: Fortinet FortiOS Buffer Overflow Flaw

CVE-2024-26010 Overview

CVE-2024-26010 is a stack-based buffer overflow vulnerability affecting multiple Fortinet products including FortiOS, FortiPAM, FortiProxy, and FortiSwitchManager. This memory corruption flaw allows remote attackers to potentially execute unauthorized code or commands by sending specially crafted network packets to vulnerable devices. The vulnerability stems from improper bounds checking during packet processing, which can lead to stack memory corruption.

Critical Impact

Remote attackers can exploit this stack-based buffer overflow to execute arbitrary code on affected Fortinet appliances, potentially gaining full control of enterprise network security infrastructure.

Affected Products

• Fortinet FortiOS versions 7.4.0-7.4.3, 7.2.0-7.2.7, 7.0.0-7.0.14, 6.4.0-6.4.15, 6.2.0-6.2.16, 6.0.0-6.0.18
• Fortinet FortiPAM versions 1.2.0, 1.1.0-1.1.2, 1.0.0-1.0.3
• Fortinet FortiProxy versions 7.4.0-7.4.2, 7.2.0-7.2.9, 7.0.0-7.0.15, 2.0.0-2.0.13, 1.2.0-1.2.13, 1.1.0-1.1.6, 1.0.0-1.0.7
• Fortinet FortiSwitchManager versions 7.2.0-7.2.3, 7.0.1-7.0.3

Discovery Timeline

• June 11, 2024 - CVE-2024-26010 published to NVD
• December 11, 2024 - Last updated in NVD database

Technical Details for CVE-2024-26010

Vulnerability Analysis

This vulnerability is classified under CWE-121 (Stack-based Buffer Overflow) and CWE-787 (Out-of-bounds Write). The flaw exists in the packet processing routines of multiple Fortinet security appliances. When these devices receive specially crafted network packets, insufficient validation of input data length allows an attacker to overflow stack-allocated buffers.

The attack requires network access and user interaction, adding complexity to successful exploitation. However, the potential impact is severe—successful exploitation can lead to complete compromise of confidentiality, integrity, and availability of the affected system. Given that Fortinet products serve as critical network security infrastructure (firewalls, proxy servers, privileged access management), compromise of these devices can cascade into broader network security failures.

Root Cause

The root cause is improper bounds checking during the processing of network packet data. When parsing certain packet structures, the vulnerable code copies data into a fixed-size stack buffer without adequately verifying that the input data length does not exceed the buffer capacity. This allows an attacker to overwrite adjacent stack memory, including return addresses and other critical control data.

Attack Vector

The vulnerability is exploitable over the network, though exploitation requires certain conditions to be met including user interaction. An attacker would craft malicious network packets designed to trigger the buffer overflow condition. The specially crafted packets contain oversized data fields that, when processed by the vulnerable Fortinet appliance, cause stack memory corruption.

The attack mechanism involves sending network packets containing data that exceeds the expected buffer size. When the vulnerable code processes these packets, the excess data overwrites adjacent stack memory. If the attacker carefully controls the overflow data, they can overwrite the function's return address, redirecting execution flow to attacker-controlled code.

For technical details regarding the specific packet structures involved, refer to the FortiGuard Security Advisory.

Detection Methods for CVE-2024-26010

Indicators of Compromise

• Unusual crash logs or core dumps from Fortinet appliances indicating memory corruption
• Unexpected network traffic patterns or malformed packets targeting Fortinet management interfaces
• Process anomalies or unexpected child processes spawned by Fortinet services
• System integrity alerts indicating modification of critical files or configurations

Detection Strategies

• Monitor network traffic for anomalously large or malformed packets destined for Fortinet appliances
• Implement intrusion detection signatures to identify potential exploitation attempts
• Enable enhanced logging on Fortinet devices to capture detailed packet processing information
• Deploy endpoint detection and response (EDR) solutions capable of detecting memory corruption exploitation attempts

Monitoring Recommendations

• Configure SIEM alerts for Fortinet device crashes, restarts, or memory-related errors
• Establish baseline network behavior and alert on deviations in traffic to Fortinet management ports
• Monitor for unauthorized configuration changes on Fortinet appliances
• Review Fortinet device logs regularly for signs of exploitation attempts or successful compromise

How to Mitigate CVE-2024-26010

Immediate Actions Required

• Identify all Fortinet FortiOS, FortiPAM, FortiProxy, and FortiSwitchManager deployments in your environment
• Cross-reference installed versions against the affected version ranges listed above
• Prioritize patching for internet-facing and critical infrastructure devices
• Implement network segmentation to limit exposure of vulnerable appliances during the patching process

Patch Information

Fortinet has released security updates to address this vulnerability. Organizations should upgrade to patched versions as specified in the official FortiGuard Security Advisory FG-IR-24-036. Review the advisory for specific fixed version numbers for each affected product line.

Workarounds

• Restrict network access to Fortinet device management interfaces to trusted networks only
• Implement strict firewall rules to limit who can send packets to affected appliances
• Enable additional logging and monitoring to detect potential exploitation attempts
• Consider deploying a web application firewall (WAF) or intrusion prevention system (IPS) in front of vulnerable devices

# Example: Restrict management interface access (FortiOS CLI)
config system interface
    edit "mgmt"
        set allowaccess ping https ssh
        set trusted-hosts 10.0.0.0/8 192.168.1.0/24
    next
end