CVE-2016-1288 in Web Security Appliance
Summary
by MITRE
The HTTPS Proxy feature in Cisco AsyncOS before 8.5.3-051 and 9.x before 9.0.0-485 on Web Security Appliance (WSA) devices allows remote attackers to cause a denial of service (service outage) by leveraging certain intranet connectivity and sending a malformed HTTPS request, aka Bug ID CSCuu24840.
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Analysis
by VulDB Data Team • 07/08/2022
The vulnerability described in CVE-2016-1288 represents a critical denial of service flaw within Cisco's Web Security Appliance platform that affects multiple software versions including AsyncOS 8.5.3-051 and earlier releases, as well as 9.x versions prior to 9.0.0-485. This issue specifically targets the HTTPS proxy functionality that is integral to the Web Security Appliance's operation, which serves as a critical security control for organizations managing web traffic and content filtering. The vulnerability resides in how the appliance processes certain HTTPS requests that originate from internal network sources, creating a scenario where remote attackers can exploit this weakness to disrupt service availability.
The technical exploitation mechanism involves attackers leveraging their ability to establish intranet connectivity to the affected WSA device and then sending specifically crafted malformed HTTPS requests that trigger a processing error within the proxy component. This flaw falls under the category of improper input validation as outlined in CWE-20, where the system fails to properly validate or sanitize incoming request data before processing. The vulnerability is particularly concerning because it allows remote attackers to cause a service outage without requiring authentication or physical access to the device, making it an attractive target for malicious actors seeking to disrupt business operations.
The operational impact of this vulnerability extends beyond simple service disruption as it can lead to complete loss of web security protection for organizations relying on the affected WSA appliances. When exploited successfully, the denial of service condition can result in complete interruption of web traffic filtering capabilities, potentially allowing malicious web content to bypass security controls. Organizations may experience significant downtime while administrators work to restore service, and the attack can occur from external networks, making it difficult to distinguish from legitimate network issues. The vulnerability particularly affects enterprises that depend on centralized web security management and have extensive internal network connectivity to their security appliances.
Security professionals should consider this vulnerability in the context of the MITRE ATT&CK framework, specifically under the T1499 technique for Network Denial of Service, where adversaries seek to disrupt network services through various methods. The weakness creates a persistent risk for organizations that may not immediately detect the service disruption, as the attack can be subtle and may not generate obvious security alerts. Organizations should prioritize patching their affected WSA appliances to address this vulnerability, as the fix typically involves updating to the patched versions that contain improved input validation and request processing mechanisms. Additionally, network segmentation and monitoring solutions should be implemented to detect unusual traffic patterns that might indicate exploitation attempts, and regular security assessments should be conducted to identify similar vulnerabilities in other network security components.