Cisco Talos has recently noticed a sudden spike in exploitation attempts against a specific vulnerability in our Cisco Adaptive Security Appliance (ASA) and Firepower Appliance. The vulnerability, CVE-2018-0296, is a denial-of-service and information disclosure directory traversal bug found in the web framework of the appliance. The attacker can use a specially crafted URL to cause the ASA appliance to reboot or disclose unauthenticated information.
This vulnerability was first noticed being exploited publicly back in June 2018, but it appeared to increase in frequency in the past several days and weeks. As such, we are advising all customers to ensure they are running a non-affected version of code. Additionally, we want to highlight that there is a Snort signature in place to detect this specific attack (46897). Concerned customers should ensure it is enabled in applicable policies that could detect this exploitation attempt.