A vulnerability, which was classified as problematic, was found in Cisco ASA and Firepower Threat Defense (Firewall Software) (unknown version). Affected is an unknown code block of the component WebVPN Login. The manipulation as part of a Request leads to a resource consumption vulnerability. CWE is classifying the issue as CWE-400. The product does not properly control the allocation and maintenance of a limited resource, thereby enabling an actor to influence the amount of resources consumed, eventually leading to the exhaustion of available resources. This is going to have an impact on availability. CVE summarizes:

A vulnerability in the WebVPN login process of Cisco Adaptive Security Appliance (ASA) Software and Cisco Firepower Threat Defense (FTD) Software could allow an unauthenticated, remote attacker to cause increased CPU utilization on an affected device. The vulnerability is due to excessive processing load for existing WebVPN login operations. An attacker could exploit this vulnerability by sending multiple WebVPN login requests to the device. A successful exploit could allow the attacker to increase CPU load on the device, resulting in a denial of service (DoS) condition.

The bug was discovered 05/01/2019. The weakness was presented 05/03/2019 as cisco-sa-20190501-sd-cpu-dos as confirmed advisory (Website). The advisory is shared for download at tools.cisco.com. This vulnerability is traded as CVE-2018-15388 since 08/17/2018. It is possible to launch the attack remotely. The exploitation doesn't require any form of authentication. There are neither technical details nor an exploit publicly available. The current price for an exploit might be approx. USD $5k-$25k (estimation calculated on 09/12/2023). The MITRE ATT&CK project declares the attack technique as T1499.

The vulnerability was handled as a non-public zero-day exploit for at least 2 days. During that time the estimated underground price was around $5k-$25k. The commercial vulnerability scanner Qualys is able to test this issue with plugin 316449 (Cisco Adaptive Security Appliance Software WebVPN Denial of Service Vulnerability(cisco-sa-20190501-sd-cpu-dos)).

There is no information about possible countermeasures known. It may be suggested to replace the affected object with an alternative product.

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• Firewall Software

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• Cisco

Name

• ASA
• Firepower Threat Defense

License

• commercial

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