Horizon Alert
Summary of the vulnerability and why it matters
The libcasper(3) library, used in FreeBSD, communicates with helper processes. A weakness in how it manages communication channels can lead to stack corruption. If a program using this library runs with elevated privileges, this corruption could be exploited for local privilege escalation.
- Vulnerable FreeBSD library component.
- Failure to limit file descriptor usage.
- Potential for unauthorized system access.
Attack Path
How an attacker could exploit the issue
The libcasper library communicates with helper processes using UNIX domain sockets and a select system call. An issue exists where the library does not validate that the socket descriptor count fits within the select system call's limit. This could lead to stack corruption if an application using libcasper opens a large number of file descriptors without properly closing them. If the affected application runs with root privileges, this corruption could enable local privilege escalation.
- Requires local access to the system.
- Attacker causes many file descriptors.
- Triggers stack corruption for privilege escalation.
Live Threat
Current exploitation, exposure, and threat context
A vulnerability exists that could allow for privilege escalation on affected systems. This occurs when an application using libcasper(3) opens a large number of file descriptors without properly closing them. If the application runs with root privileges, this condition could be exploited to gain elevated access. The risk is associated with local access, meaning an attacker would need to be on the system already to trigger the vulnerability.
- Likely attacker skill level: Low
- Required access or conditions: Local access required
- Business risk or urgency: Moderate
Priority actions
Operational Fix
Recommended remediation, mitigation, and detection steps
A vulnerability exists in libcasper(3) that could allow a local attacker to escalate privileges. The issue stems from a failure to properly validate the size of file descriptors used with the select(2) system call, potentially leading to stack corruption if the application runs with elevated privileges. Organizations should prioritize understanding their exposure and mitigating this risk.
- Identify systems using libcasper(3).
- Limit file descriptor usage where possible.
- Apply vendor fixes and verify.
- Monitor for related activities.
