CVE-2018-0095 in Email Security Appliance
Summary
by MITRE
A vulnerability in the administrative shell of Cisco AsyncOS on Cisco Email Security Appliance (ESA) and Content Security Management Appliance (SMA) could allow an 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 level of a guest user. The vulnerability is due to an incorrect networking configuration at the administrative shell CLI. An attacker could exploit this vulnerability by authenticating to the targeted device and issuing a set of crafted, malicious commands at the administrative shell. An exploit could allow the attacker to gain root access on the device. Cisco Bug IDs: CSCvb34303, CSCvb35726.
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Analysis
by VulDB Data Team • 02/01/2021
The vulnerability identified as CVE-2018-0095 represents a critical privilege escalation flaw within the administrative shell of Cisco AsyncOS operating on Email Security Appliances and Content Security Management Appliances. This security weakness specifically targets the command-line interface of the administrative shell where improper network configuration creates opportunities for malicious exploitation. The vulnerability requires only a valid user credential with guest-level privileges to initiate exploitation, making it particularly concerning as it can be leveraged by attackers who have already gained some level of access to the system. The flaw stems from inadequate validation and handling of administrative commands within the shell environment, creating a pathway for authenticated local attackers to escalate their privileges beyond the initial access level.
The technical exploitation of this vulnerability occurs through carefully crafted commands issued within the administrative shell interface. Attackers with guest-level credentials can manipulate the shell's networking configuration to execute malicious operations that ultimately result in root access. The vulnerability is categorized under CWE-269 Privilege Escalation, specifically involving improper privilege management within administrative interfaces. The exploitation process involves leveraging the misconfigured shell environment to bypass normal access controls and elevate privileges to the highest system level. This type of attack aligns with ATT&CK technique T1068 Privilege Escalation through the manipulation of system interfaces and command execution environments.
The operational impact of CVE-2018-0095 extends beyond simple privilege escalation as it provides attackers with complete system control over affected Cisco appliances. Once root access is achieved, malicious actors can modify system configurations, install backdoors, access all email traffic, and potentially use the compromised appliance as a pivot point for attacking other network segments. The vulnerability affects multiple Cisco products including the Email Security Appliance and Content Security Management Appliance, making it a widespread concern for organizations relying on these security solutions. The attack vector remains local to the device itself, meaning that exploitation does not require network exposure or external attack surfaces, though it can be leveraged as a stepping stone for broader network compromise. The vulnerability's impact is particularly severe because it undermines the fundamental security model of these appliances, which are designed to protect network email traffic and content.
Organizations should implement immediate mitigations including applying the relevant Cisco security patches and updates that address the administrative shell configuration issues. System administrators should also enforce strict access controls and privilege management policies, ensuring that only necessary personnel have access to administrative functions. Network segmentation and monitoring of administrative shell activities can help detect unauthorized access attempts. The vulnerability demonstrates the importance of proper access control implementation in administrative interfaces and highlights the need for regular security assessments of critical infrastructure components. Additionally, organizations should consider implementing multi-factor authentication for administrative access and maintain comprehensive audit logs of all administrative activities to detect potential exploitation attempts. The Cisco bug IDs CSCvb34303 and CSCvb35726 indicate that this was a known issue requiring specific patches to resolve the underlying configuration problems in the administrative shell environment.