Horizon Alert
Summary of the vulnerability and why it matters
A vulnerability exists in the crypto engine of the Cisco Integrated Services Module for VPN (ISM-VPN) that runs Cisco IOS Software. This flaw could allow an attacker to disrupt services. The issue stems from how the device handles VPN traffic.
- Cisco ISM-VPN and Cisco IOS Software
- Insufficient handling of VPN traffic
- Denial of service impacting operations
Attack Path
How an attacker could exploit the issue
An unauthenticated, remote attacker can exploit this vulnerability by sending crafted VPN traffic to an affected device. This can cause the device to hang or crash, resulting in a denial-of-service condition that impacts network operations. The vulnerability is related to the crypto engine's insufficient handling of VPN traffic within the Cisco Integrated Services Module for VPN (ISM-VPN).
- Exposure condition: Public-facing VPN service.
- Attacker starting point: Remote network access.
- Trigger and result: Crafted VPN traffic causes denial of service.
Live Threat
Current exploitation, exposure, and threat context
A remote, unauthenticated attacker can exploit this vulnerability by sending specially crafted VPN traffic to an affected device. This exploit can cause the device to hang or crash, leading to a denial-of-service condition. The vulnerability is present in the crypto engine of the Cisco Integrated Services Module for VPN (ISM-VPN) running Cisco IOS Software. The U.S. Cybersecurity and Infrastructure Security Agency (CISA) has added this vulnerability to its Known Exploited Vulnerabilities (KEV) catalog, indicating active exploitation in the wild.
- Likely attacker skill level: Unknown, but likely requires technical expertise.
- Required access or conditions: Remote and unauthenticated network access.
- Business risk or urgency: High; requires immediate attention.
Priority actions
Operational Fix
Recommended remediation, mitigation, and detection steps
This vulnerability could allow an unauthenticated, remote attacker to cause a denial-of-service condition on affected Cisco devices. The issue stems from insufficient handling of VPN traffic, potentially leading to device hangs or crashes. The risk is categorized as external, meaning the attack vector is over the network.
- Identify exposed VPN modules.
- Restrict VPN traffic access.
- Apply vendor fixes and verify.
- Monitor for related issues.
