CVE-2023-23777 - OS Command Injection Vulnerability in FortiWeb Allowing Arbitrary Bash Command Execution

A recent vulnerability, assigned the identifier CVE-2023-23777, has been discovered affecting FortiWeb versions 7..1 and below, all versions of 6.4, and 6.3.18 and below. This vulnerability, classified as an OS Command Injection (CWE-78), allows an authenticated attacker with privileges to potentially execute arbitrary bash commands through specially crafted command parameters. This blog post details the vulnerability, provides a code snippet demonstrating the issue, and discusses possible mitigation strategies.

Vulnerability

The CVE-2023-23777 vulnerability involves the improper neutralization of special elements used in an OS command in FortiWeb. An attacker with the appropriate privileges can exploit this vulnerability by crafting specific CLI backup parameters that inject arbitrary bash commands into the system. This can potentially lead to unauthorized access and control over affected FortiWeb systems.

Exploit details

In order to exploit this vulnerability, the attacker would require authenticated access to the target system as well as sufficient privileges to manipulate CLI backup parameters. The following is a code snippet demonstrating an example exploit:

# Attacker injects malicious command
backup_config = "backup.tar.gz; rm -rf /important/data"
# FortiWeb improperly neutralizes special elements in backup_config
cmd = "tar -czvf " + backup_config + " /etc/config"
# Resulting command: tar -czvf backup.tar.gz; rm -rf /important/data /etc/config
os.system(cmd)

In this example, the attacker has maliciously modified the backup_config parameter to include a bash command following a semicolon. When FortiWeb constructs and executes the OS command using the attacker-controlled backup_config parameter, the malicious command is executed, leading to potential data loss and unauthorized access.

For further details about this vulnerability, consult the following resources

1. CVE-2023-23777: The MITRE Corporation's official entry for this vulnerability, including the description, affected versions, and references.
2. CWE-78: MITRE's Common Weakness Enumeration entry for OS Command Injection vulnerabilities, providing background information and common consequences.
3. FortiWeb Security Advisory: An (imaginary) official security advisory from Fortinet discussing the vulnerability, affected versions, and recommended mitigation strategies.

Mitigation

To protect against the exploitation of CVE-2023-23777, it is recommended to follow the mitigation strategies provided by Fortinet:

1. Update to the latest version of FortiWeb: Systems administrators should promptly update their affected FortiWeb installations to version 7..2 or newer, or version 6.3.19 or newer for the 6.3.x branch.
2. Limit access: Ensure that only trusted personnel have access to FortiWeb administrative interfaces, and enforce the principle of least privilege to minimize the potential for unauthorized access and manipulation.
3. Network segmentation: Isolate FortiWeb systems from untrusted or less secure networks to reduce the potential attack surface.
4. Regular monitoring and auditing: Regularly examine logs and system configurations for signs of unauthorized access or potential security weaknesses.

Conclusion

The CVE-2023-23777 vulnerability is a significant security concern for organizations using affected versions of FortiWeb. By understanding the exploit details and implementing the recommended mitigation strategies, organizations can better safeguard their critical assets and remain resilient against potential attacks.

Timeline

Published on: 07/11/2023 09:15:09 UTC
Last modified on: 11/07/2023 04:07:56 UTC