CVE-2009-1262 in FortiClient
Summary
by MITRE
Format string vulnerability in Fortinet FortiClient 3.0.614, and possibly earlier, allows local users to execute arbitrary code via format string specifiers in the VPN connection name.
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Analysis
by VulDB Data Team • 04/06/2025
The vulnerability identified as CVE-2009-1262 represents a critical format string vulnerability affecting Fortinet FortiClient version 3.0.614 and potentially earlier releases. This security flaw resides within the VPN connection name handling mechanism of the client software, creating a pathway for local attackers to execute arbitrary code on affected systems. The vulnerability stems from improper input validation and handling of user-supplied data within the application's string formatting functions, which are commonly exploited in buffer overflow and code execution attacks.
The technical implementation of this vulnerability occurs when the FortiClient application processes VPN connection names that contain format string specifiers such as %s, %d, or other printf-style formatting characters. When these malformed strings are processed through vulnerable printf-family functions without proper sanitization, the application's memory layout becomes corrupted, potentially allowing an attacker to manipulate stack pointers and execute malicious code. This type of vulnerability falls under the CWE-134 category of Use of Externally-Controlled Format String, which is classified as a high-severity issue in the Common Weakness Enumeration catalog. The attack vector is particularly concerning because it requires only local system access, making it accessible to users who already have legitimate credentials or system privileges.
The operational impact of this vulnerability extends beyond simple code execution, as local attackers with minimal privileges can leverage this flaw to escalate their system access and potentially gain administrative control over the affected device. The vulnerability affects enterprise environments where FortiClient is deployed for remote access, as compromised endpoints could serve as entry points for broader network infiltration. From an adversarial perspective, this vulnerability aligns with techniques described in the MITRE ATT&CK framework under the T1059.007 sub-technique for Command and Scripting Interpreter: PowerShell, where attackers exploit local vulnerabilities to establish persistent access. The local execution requirement reduces detection likelihood compared to remote exploits, making this vulnerability particularly dangerous in environments where endpoint protection is insufficient.
Mitigation strategies for CVE-2009-1262 should prioritize immediate patching of FortiClient installations to versions that address the format string vulnerability in the VPN connection handling functionality. Organizations should implement strict input validation controls within their VPN client configurations to prevent the acceptance of format string specifiers in connection name fields. Network segmentation and privilege separation measures can limit the potential impact of successful exploitation by reducing local user privileges and implementing principle of least privilege access controls. Security monitoring should focus on detecting unusual process execution patterns and memory access anomalies that might indicate exploitation attempts. Additionally, regular vulnerability assessments and penetration testing should be conducted to identify similar format string vulnerabilities in other network security tools and applications. The remediation process should include comprehensive testing of patched versions to ensure that the vulnerability is fully resolved without introducing regressions in functionality.