CVE-2023-42782 in FortiAnalyzer
Summary
by MITRE • 10/25/2023
A insufficient verification of data authenticity vulnerability [CWE-345] in FortiAnalyzer version 7.4.0 and below 7.2.3 allows a remote unauthenticated attacker to send messages to the syslog server of FortiAnalyzer via the knoweldge of an authorized device serial number.
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Analysis
by VulDB Data Team • 10/25/2023
This vulnerability represents a critical weakness in FortiAnalyzer's authentication mechanisms that stems from inadequate verification of data authenticity as classified under CWE-345. The flaw exists in versions 7.4.0 and below 7.2.3 of the security information and event management platform, creating a significant attack surface for remote threat actors. The vulnerability specifically affects the syslog server component where legitimate device serial numbers can be exploited by unauthorized parties to inject malicious messages into the system. This weakness fundamentally undermines the integrity of the logging infrastructure by allowing attackers to bypass normal authentication requirements through simple reconnaissance of valid serial numbers.
The technical implementation of this vulnerability exploits the lack of proper cryptographic verification or digital signature validation when processing incoming syslog messages. Attackers who obtain knowledge of a legitimate device serial number can leverage this information to send forged syslog messages to the FortiAnalyzer system without requiring authentication credentials. The flaw essentially creates a backdoor mechanism where the system accepts messages based solely on serial number validation rather than implementing robust authentication protocols. This design flaw allows for potential data manipulation, injection of false security events, and disruption of legitimate logging operations. The vulnerability is particularly concerning because it requires no prior authentication and can be exploited remotely, making it accessible to anyone who can discover valid serial numbers within the network.
The operational impact of this vulnerability extends beyond simple message injection to potentially compromise the entire security monitoring infrastructure. An attacker could flood the system with false positive alerts, creating alert fatigue that could mask actual security incidents. The integrity of security logs becomes compromised as malicious entries can be intermixed with legitimate system messages, making forensic analysis and threat hunting significantly more challenging. This vulnerability could also enable attackers to manipulate security event correlations, potentially allowing them to hide their activities within legitimate traffic patterns. The affected FortiAnalyzer versions may be widely deployed in enterprise environments, amplifying the potential impact of this vulnerability across multiple organizations that rely on accurate security logging for threat detection and compliance reporting.
Organizations should immediately implement mitigations including network segmentation to limit access to syslog ports, deployment of additional authentication layers, and monitoring for unusual syslog message patterns. The vulnerability aligns with ATT&CK technique T1070.002 for "Indicator Removal on Host" as attackers could potentially cover their tracks by injecting false log entries. Security teams should also consider implementing network access controls to restrict syslog message transmission to authorized devices only. Regular updates to FortiAnalyzer versions should be prioritized, with particular attention to versions 7.2.3 and above where the vulnerability has been addressed. Additionally, organizations should conduct thorough audits of their serial number management practices and implement more robust device identification mechanisms that do not rely solely on easily discoverable identifiers. The vulnerability demonstrates the critical importance of implementing multi-factor authentication and proper cryptographic verification in security infrastructure components to prevent unauthorized access and maintain data integrity across the entire security monitoring ecosystem.