CVE-2017-6783 in Web Security Appliance
Summary
by MITRE
A vulnerability in SNMP polling for the Cisco Web Security Appliance (WSA), Email Security Appliance (ESA), and Content Security Management Appliance (SMA) could allow an authenticated, remote attacker to discover confidential information about the appliances that should be available only to an administrative user. The vulnerability occurs because the appliances do not protect confidential information at rest in response to Simple Network Management Protocol (SNMP) poll requests. An attacker could exploit this vulnerability by doing a crafted SNMP poll request to the targeted security appliance. An exploit could allow the attacker to discover confidential information that should be restricted, and the attacker could use this information to conduct additional reconnaissance. The attacker must know the configured SNMP community string to exploit this vulnerability. Cisco Bug IDs: CSCve26106, CSCve26202, CSCve26224. Known Affected Releases: 10.0.0-230 (Web Security Appliance), 9.7.2-065 (Email Security Appliance), and 10.1.0-037 (Content Security Management Appliance).
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Analysis
by VulDB Data Team • 01/09/2021
The vulnerability identified as CVE-2017-6783 represents a significant security weakness in Cisco's line of security appliances including the Web Security Appliance WSA, Email Security Appliance ESA, and Content Security Management Appliance SMA. This flaw resides in the SNMP polling implementation and demonstrates a critical failure in information access control mechanisms. The vulnerability stems from insufficient protection of confidential data at rest when responding to SNMP requests, creating an information disclosure risk that directly violates fundamental security principles of data confidentiality and access control. The issue affects specific software versions where the appliances fail to properly validate and restrict access to sensitive information during SNMP query processing, allowing unauthorized disclosure of administrative-level data.
The technical exploitation of this vulnerability requires an authenticated remote attacker who possesses the valid SNMP community string configured on the target appliance. This prerequisite aligns with CWE-284 which addresses improper access control issues, specifically the failure to properly restrict access to sensitive information. The attacker can craft specific SNMP polling requests that trigger the appliance to respond with confidential data that should normally be restricted to administrative users only. This behavior constitutes a violation of the principle of least privilege and demonstrates inadequate input validation and access control enforcement within the SNMP response handling mechanism. The vulnerability specifically affects the response processing of SNMP queries rather than the query itself, making it a targeted information disclosure flaw that leverages existing authentication mechanisms.
The operational impact of this vulnerability extends beyond simple information disclosure to enable more sophisticated reconnaissance activities by threat actors. When an attacker successfully exploits this vulnerability, they gain access to confidential information that could include system configurations, network topology details, user accounts, or other sensitive administrative data. This intelligence gathering capability allows attackers to conduct more targeted and effective attacks against the affected appliances and potentially the broader network infrastructure they protect. The vulnerability creates a pathway for attackers to escalate their privileges or identify additional attack vectors, making it particularly dangerous in enterprise environments where these appliances serve as critical security controls. The exposure of administrative information undermines the security posture of organizations relying on these appliances for network protection.
Mitigation strategies for CVE-2017-6783 should focus on restricting SNMP access to only trusted administrative networks and implementing strict access controls for SNMP community strings. Organizations must ensure that SNMP community strings are properly configured with strong authentication mechanisms and that SNMP polling is restricted to authorized administrative systems only. The implementation of network segmentation and firewall rules to limit SNMP traffic to trusted sources represents a critical defensive measure. Additionally, regular security assessments should verify that SNMP configurations follow security best practices and that sensitive information is properly protected even when responding to legitimate SNMP queries. The vulnerability highlights the importance of applying security patches promptly and maintaining up-to-date software versions to prevent exploitation of known weaknesses. Organizations should also consider implementing monitoring solutions to detect unauthorized SNMP polling activities that could indicate attempted exploitation of this vulnerability. This case exemplifies the ATT&CK technique of credential access through network service scanning and information gathering, demonstrating how weaknesses in network management protocols can be exploited to compromise security controls.