CVE-2023-29182 in FortiOS
Summary
by MITRE • 08/17/2023
A stack-based buffer overflow vulnerability [CWE-121] in Fortinet FortiOS before 7.0.3 allows a privileged attacker to execute arbitrary code via specially crafted CLI commands, provided the attacker were able to evade FortiOS stack protections.
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Analysis
by VulDB Data Team • 09/02/2023
The vulnerability identified as CVE-2023-29182 represents a critical stack-based buffer overflow flaw classified under CWE-121 within Fortinet FortiOS versions prior to 7.0.3. This vulnerability exists in the command line interface processing mechanism where the system fails to properly validate input length before copying data to a fixed-size stack buffer. The flaw specifically manifests when handling specially crafted CLI commands that exceed the allocated buffer space, creating a condition where adjacent memory locations can be overwritten with attacker-controlled data.
The technical implementation of this vulnerability leverages the fundamental weakness of stack-based buffer overflows where input validation is insufficient to prevent excessive data from being written to stack memory regions. When a privileged attacker submits malicious CLI commands containing oversized payloads, the system's input handling routines fail to enforce proper bounds checking, allowing the overflow to occur. This condition creates opportunities for memory corruption that can be exploited to redirect program execution flow. The vulnerability requires an attacker to already possess privileged access to the system, as the exploitation targets the command line interface processing which typically requires administrative credentials. However, the requirement for privileged access does not diminish the severity of the vulnerability since such credentials are often targeted in security breaches and can be obtained through various attack vectors.
The operational impact of this vulnerability extends beyond simple code execution as it provides a potential pathway for privilege escalation and persistent access within the network infrastructure. When successfully exploited, the buffer overflow can allow an attacker to execute arbitrary code with the privileges of the FortiOS process, which typically runs with elevated system permissions. This capability enables attackers to gain unauthorized access to sensitive network data, modify security policies, establish backdoors, or conduct further reconnaissance within the network environment. The vulnerability's presence in the CLI processing layer means that legitimate administrative functions could be disrupted while simultaneously providing a covert channel for malicious activity. Network security administrators face significant challenges in detecting such exploits since they may appear as legitimate administrative commands, making the vulnerability particularly dangerous in environments where logging and monitoring are insufficient.
The exploitation of this vulnerability aligns with several tactics described in the MITRE ATT&CK framework, particularly those related to privilege escalation and execution through command-line interfaces. The requirement for a privileged attacker position this vulnerability within the context of lateral movement and persistence tactics where attackers have already gained initial access to administrative accounts. Security professionals should consider implementing additional monitoring for anomalous CLI command patterns and ensure that all FortiOS devices are updated to version 7.0.3 or later. The vulnerability's classification under CWE-121 indicates that it stems from inadequate bounds checking in stack-based memory operations, a common pattern that should be addressed through proper input validation and secure coding practices. Organizations should also implement network segmentation and access controls to limit the potential impact of successful exploitation, while maintaining regular security assessments to identify similar vulnerabilities across their network infrastructure. The presence of stack protection mechanisms within FortiOS suggests that the system employs some level of security hardening, but the vulnerability demonstrates that these protections can be bypassed by sophisticated attackers.