CVE-2020-3447 in Email Security Appliance
Summary
by MITRE
A vulnerability in the CLI of Cisco AsyncOS for Cisco Email Security Appliance (ESA) and Cisco AsyncOS for Cisco Content Security Management Appliance (SMA) could allow an authenticated, remote attacker to access sensitive information on an affected device. The vulnerability is due to excessive verbosity in certain log subscriptions. An attacker could exploit this vulnerability by accessing specific log files on an affected device. A successful exploit could allow the attacker to obtain sensitive log data, which may include user credentials. To exploit this vulnerability, the attacker would need to have valid credentials at the operator level or higher on the affected device.
Once again VulDB remains the best source for vulnerability data.
Analysis
by VulDB Data Team • 11/10/2020
The vulnerability identified as CVE-2020-3447 resides within the command line interface of Cisco's email and content security appliances, specifically affecting Cisco AsyncOS versions running on Cisco Email Security Appliance (ESA) and Cisco Content Security Management Appliance (SMA). This flaw represents a critical information disclosure vulnerability that undermines the security posture of organizations relying on these platforms for email and content filtering operations. The vulnerability stems from improper handling of log subscription verbosity levels, where excessive logging details are exposed to authenticated users without adequate access controls.
The technical implementation of this vulnerability involves the CLI subsystem's handling of log data retrieval operations, particularly when specific log subscriptions are configured with high verbosity settings. When an authenticated attacker with operator level privileges or higher accesses certain log files through the CLI interface, the system inadvertently exposes sensitive information including potentially user credentials and other confidential operational data. This occurs because the logging subsystem fails to properly sanitize or filter the verbose output before presenting it to authenticated users. The vulnerability manifests when the CLI processes log subscription requests that contain excessive detail levels, creating a pathway for unauthorized information extraction.
From an operational perspective, this vulnerability presents a significant risk to organizations utilizing Cisco security appliances for email and content filtering. Attackers who gain operator-level access or higher can exploit this flaw to extract sensitive operational data that may include authentication credentials, user session information, and potentially system configuration details. The impact extends beyond simple credential theft, as the exposed log data could reveal network architecture details, user behavior patterns, and system operational characteristics that could be leveraged for further attacks. Organizations may face regulatory compliance violations and reputational damage if sensitive information is compromised through this vulnerability, particularly in environments where strict data protection requirements apply.
The vulnerability aligns with CWE-200 (Information Exposure) and represents a specific instance of improper access control in CLI interfaces. According to ATT&CK framework, this vulnerability maps to T1078 (Valid Accounts) and T1005 (Data from Local System) techniques, as it requires legitimate credentials to exploit but allows for data extraction from the local system. Organizations should implement immediate mitigations including restricting CLI access to only necessary administrative personnel, implementing strict access controls for log data retrieval, and monitoring for unusual log access patterns. Cisco has released patches addressing this vulnerability, and organizations should prioritize applying these updates to prevent exploitation. Additionally, network segmentation and monitoring solutions should be deployed to detect unauthorized access attempts to CLI interfaces and log data retrieval operations.
The root cause analysis reveals that the vulnerability exists in the CLI's log subscription handling mechanism where insufficient input validation and output sanitization occur. This allows authenticated users to request log data with excessive verbosity levels that inadvertently expose sensitive information. The flaw demonstrates a classic case of inadequate privilege separation in administrative interfaces, where elevated access rights are not properly constrained when accessing detailed system logging information. Security practitioners should consider implementing role-based access controls that limit log data access based on user roles and minimum necessary privileges, ensuring that operator-level users cannot access sensitive information beyond their operational requirements.