CVE-2022-20729 in Firepower Threat Defense
Summary
by MITRE • 05/03/2022
A vulnerability in CLI of Cisco Firepower Threat Defense (FTD) Software could allow an authenticated, local attacker to inject XML into the command parser. This vulnerability is due to insufficient input validation. An attacker could exploit this vulnerability by including crafted input in commands. A successful exploit could allow the attacker to inject XML into the command parser, which could result in unexpected processing of the command and unexpected command output.
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Analysis
by VulDB Data Team • 05/05/2022
Cisco Firepower Threat Defense software contains a critical command line interface vulnerability that enables authenticated local attackers to perform XML injection attacks through insufficient input validation mechanisms. This vulnerability specifically affects the XML command parser within the FTD CLI, creating a pathway for attackers to manipulate command execution flows by introducing malicious XML content into command inputs. The flaw stems from inadequate sanitization of user-supplied data before processing within the XML parser, allowing crafted payloads to bypass normal input validation checks and be interpreted as part of the command structure rather than as simple data.
The technical exploitation of this vulnerability requires an attacker to possess valid authentication credentials for the FTD system, establishing a local attack vector that leverages existing access privileges to escalate command processing behavior. When malicious XML content is included in CLI commands, the parser processes this injected XML alongside legitimate command parameters, potentially causing the system to execute unintended operations or produce unexpected output that could reveal system information or facilitate further exploitation. This vulnerability aligns with CWE-94, which describes insufficient input validation leading to code injection, and specifically manifests as an XML injection vulnerability within command line interfaces.
The operational impact of this vulnerability extends beyond simple command manipulation, as successful exploitation could enable attackers to access sensitive system information, modify command behavior, or potentially execute arbitrary code within the context of the CLI process. Attackers could leverage this weakness to craft commands that appear legitimate to the system but contain hidden XML payloads that alter execution flow or extract data through unexpected command responses. The local nature of this vulnerability means that attackers do not require network access to exploit it, making it particularly concerning for environments where physical access or legitimate administrative credentials are compromised. This weakness maps to attack techniques in the MITRE ATT&CK framework under T1059.006 for Command and Scripting Interpreter with XML injection methods.
Organizations should implement immediate mitigations including enforcing strict input validation controls within the FTD CLI, applying the latest security patches from Cisco, and implementing principle of least privilege access controls for CLI access. Network segmentation and monitoring of CLI activities can help detect anomalous command patterns that might indicate exploitation attempts. Security teams should also consider implementing additional authentication controls and access logging for CLI sessions to detect unauthorized access attempts. The vulnerability demonstrates the importance of validating all user inputs in command processing systems and highlights the risks associated with insufficient sanitization of structured data formats like XML within CLI environments. Regular security assessments of CLI interfaces and input validation mechanisms should be conducted to identify similar weaknesses that could enable similar injection attacks.