CVE-2021-43072 in FortiAnalyzer
Summary
by MITRE • 07/18/2023
A buffer copy without checking size of input ('classic buffer overflow') in Fortinet FortiAnalyzer version 7.0.2 and below, version 6.4.7 and below, version 6.2.9 and below, version 6.0.11 and below, version 5.6.11 and below, FortiManager version 7.0.2 and below, version 6.4.7 and below, version 6.2.9 and below, version 6.0.11 and below, version 5.6.11 and below, FortiOS version 7.0.0 through 7.0.4, 6.4.0 through 6.4.8, 6.2.0 through 6.2.10, 6.0.x and FortiProxy version 7.0.0 through 7.0.3, 2.0.0 through 2.0.8, 1.2.x, 1.1.x and 1.0.x allows attacker to execute unauthorized code or commands via crafted CLI `execute restore image` and `execute certificate remote` operations with the tFTP protocol.
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Analysis
by VulDB Data Team • 10/27/2024
This vulnerability represents a classic buffer overflow condition that exists within multiple Fortinet security products including FortiAnalyzer, FortiManager, FortiOS, and FortiProxy systems. The flaw manifests when processing crafted command line interface inputs during specific restore image and certificate remote operations that utilize the tFTP protocol. The vulnerability stems from insufficient input validation and size checking mechanisms that fail to properly constrain buffer boundaries during data copying operations. This fundamental security weakness allows attackers to overwrite adjacent memory locations with malicious data, potentially leading to arbitrary code execution or command injection attacks.
The technical implementation of this vulnerability involves the execution of specific CLI commands that trigger the buffer overflow condition. When an attacker crafts malicious input parameters for the `execute restore image` and `execute certificate remote` operations, the system fails to validate the input length against the allocated buffer space. This classic buffer overflow scenario enables attackers to overwrite return addresses, function pointers, or other critical memory segments. The vulnerability affects a wide range of Fortinet product versions including FortiAnalyzer 7.0.2 and below, FortiManager 7.0.2 and below, various FortiOS versions from 7.0.0 through 7.0.4 down to 5.6.11 and below, and FortiProxy versions through 7.0.3 and 2.0.8. The exploitation requires remote access capabilities through the tFTP protocol which is commonly used for firmware updates and certificate management operations.
The operational impact of this vulnerability is severe as it provides attackers with potential unauthorized code execution privileges within the affected systems. Successful exploitation could allow attackers to gain full administrative control over the vulnerable Fortinet appliances, enabling them to modify system configurations, extract sensitive data, or establish persistent backdoor access. The remote nature of the attack vector means that threat actors can exploit this vulnerability without requiring physical access to the devices, making it particularly dangerous in networked environments where these appliances serve as critical security infrastructure components. The vulnerability affects systems that rely on tFTP protocol for legitimate operations, creating a window of opportunity for attackers to compromise security controls that are essential for network monitoring and management.
Security professionals should implement immediate mitigations including restricting network access to affected devices, disabling unnecessary tFTP services where possible, and applying the latest firmware updates from Fortinet that address this specific buffer overflow condition. Organizations must also conduct thorough vulnerability assessments to identify all instances of affected Fortinet products within their network infrastructure. The vulnerability aligns with CWE-121, which describes classic stack-based buffer overflow conditions, and represents a significant risk under ATT&CK technique T1059.001 for command and scripting interpreter execution. Network segmentation and monitoring should be enhanced to detect unusual tFTP traffic patterns that might indicate exploitation attempts. Additionally, implementing proper input validation controls and employing address space layout randomization techniques can help reduce the exploitability of similar buffer overflow conditions in the future.