CVE-2023-28528 is an OS command injection vulnerability identified in IBM AIX operating system versions 7.1, 7.2, 7.3, and the Virtual I/O Server (VIOS) 3.1. The flaw exists in the invscout command, which improperly neutralizes special characters or elements used in OS commands, allowing a non-privileged local user to inject and execute arbitrary commands on the underlying system. This vulnerability is classified under CWE-78, indicating improper sanitization of inputs that are incorporated into OS command execution. The vulnerability does not require any user interaction or prior authentication, making it easier for local attackers to exploit. The CVSS v3.1 base score of 8.4 reflects a high severity due to the potential for complete system compromise, including full control over confidentiality, integrity, and availability of the affected system. While no public exploits have been reported yet, the presence of this vulnerability in widely used IBM AIX versions, especially in enterprise and critical infrastructure environments, poses a significant risk. The invscout command is typically used for system inventory and monitoring, so exploitation could allow attackers to escalate privileges or execute malicious payloads stealthily. As the vulnerability affects local users, the attack vector is limited to those with some level of access to the system, but the lack of required privileges lowers the barrier for exploitation. IBM has published the vulnerability details but has not yet released patches, so mitigation currently relies on access control and monitoring.

For European organizations, this vulnerability presents a critical risk especially in sectors relying on IBM AIX for mission-critical workloads such as finance, telecommunications, manufacturing, and government infrastructure. Exploitation could lead to unauthorized command execution, enabling attackers to manipulate system configurations, exfiltrate sensitive data, disrupt services, or establish persistent backdoors. The high severity score indicates that confidentiality, integrity, and availability could all be severely impacted. Given that the vulnerability can be exploited by non-privileged local users, insider threats or attackers gaining limited access through other means could leverage this flaw to escalate privileges and compromise entire systems. This is particularly concerning for organizations with complex, multi-user environments or those that allow remote access to AIX systems via jump hosts or VPNs. The absence of known exploits in the wild provides a window for proactive defense, but also means organizations must act swiftly to prevent potential future attacks. The impact extends to virtualized environments using VIOS 3.1, which are common in enterprise data centers, increasing the scope of affected systems.

1. Immediately restrict local user access to IBM AIX systems, especially limiting the number of users who can execute the invscout command or have shell access. 2. Implement strict access control policies and use role-based access controls (RBAC) to minimize permissions granted to local users. 3. Monitor and audit usage of the invscout command and related system commands for unusual or unauthorized activity. 4. Employ host-based intrusion detection systems (HIDS) to detect anomalous command executions or privilege escalations. 5. Isolate critical AIX systems from less trusted networks and users to reduce the risk of local exploitation. 6. Regularly review and harden system configurations, disabling unnecessary services and commands where possible. 7. Stay updated with IBM security advisories and apply official patches or updates as soon as they become available. 8. Consider deploying application whitelisting or command execution restrictions to prevent unauthorized command injections. 9. Educate system administrators and users about the risks and signs of exploitation related to this vulnerability. 10. In virtualized environments using VIOS, ensure that virtual machine isolation and access controls are enforced to prevent lateral movement.