CVE-2023-20009 in ESA
Summary
by MITRE • 03/01/2023
A vulnerability in the Web UI and administrative CLI of the Cisco Secure Email Gateway (ESA) and Cisco Secure Email and Web Manager (SMA) could allow an authenticated remote attacker and or authenticated local attacker to escalate their privilege level and gain root access. The attacker has to have a valid user credential with at least a [[privilege of operator - validate actual name]]. The vulnerability is due to the processing of a specially crafted SNMP configuration file. An attacker could exploit this vulnerability by authenticating to the targeted device and uploading a specially crafted SNMP configuration file that when uploaded could allow for the execution of commands as root. An exploit could allow the attacker to gain root access on the device.
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Analysis
by VulDB Data Team • 03/16/2023
This vulnerability resides within the Cisco Secure Email Gateway (ESA) and Cisco Secure Email and Web Manager (SMA) platforms, representing a critical privilege escalation flaw that can be exploited by authenticated attackers. The vulnerability specifically affects the web user interface and administrative command-line interface components of these security appliances, creating a pathway for attackers to elevate their privileges from operator level to root access. The flaw manifests through improper handling of specially crafted SNMP configuration files, which when processed by the affected systems can trigger unauthorized command execution with the highest system privileges. This represents a significant security risk as it allows attackers with minimal credentials to gain complete system control over email security appliances that are typically considered critical infrastructure components within enterprise networks.
The technical exploitation mechanism relies on the processing of malicious SNMP configuration files that contain crafted payloads designed to manipulate the underlying system. When an authenticated user uploads such a file through the web interface or CLI, the system fails to properly validate or sanitize the input, leading to unintended command execution with root privileges. This type of vulnerability falls under CWE-20, which describes improper input validation, and more specifically aligns with CWE-78, which addresses OS command injection vulnerabilities. The attack vector requires an authenticated session with operator-level privileges, typically limited to users who can perform basic management functions but not full administrative access. However, the vulnerability's design allows these limited users to bypass normal privilege boundaries through the SNMP configuration file processing mechanism, effectively circumventing the intended access controls.
The operational impact of this vulnerability extends far beyond simple privilege escalation, as it provides attackers with complete control over email security appliances that are fundamental to enterprise communications and security infrastructure. Once root access is achieved, attackers can modify system configurations, disable security features, access all email traffic, manipulate spam and malware filtering rules, and potentially use the compromised appliance as a pivot point for further attacks within the network. The vulnerability affects Cisco ESA and SMA appliances running specific software versions, making it particularly concerning for organizations that have deployed these platforms as part of their email security architecture. From an adversary perspective, this vulnerability maps to ATT&CK technique T1068, which covers local privilege escalation, and T1566, which involves social engineering through malicious file downloads or uploads.
Organizations should prioritize immediate remediation through official Cisco security advisories and patches, as this vulnerability can be exploited remotely by authenticated users with minimal privileges. The recommended mitigation strategy includes implementing strict access controls and limiting user accounts to the minimum necessary privileges, along with monitoring for unauthorized file uploads through the web interface. Network segmentation and monitoring of administrative interfaces can help detect suspicious activities, while regular security assessments should verify that no unauthorized modifications have occurred. The vulnerability demonstrates the importance of proper input validation and privilege separation in security appliances, as the system should never allow a user with operator privileges to execute commands with root-level access through configuration file processing. Administrators should also consider implementing additional security measures such as file integrity monitoring and privileged access management solutions to reduce the attack surface and prevent exploitation of similar vulnerabilities in the future.