CVE-2017-12261 in Identity Services Engine
Summary
by MITRE
A vulnerability in the restricted shell of the Cisco Identity Services Engine (ISE) that is accessible via SSH could allow an authenticated, local attacker to run arbitrary CLI commands with elevated privileges. The vulnerability is due to incomplete input validation of the user input for CLI commands issued at the restricted shell. An attacker could exploit this vulnerability by authenticating to the targeted device and executing commands that could lead to elevated privileges. An attacker would need valid user credentials to the device to exploit this vulnerability. The vulnerability affects the following Cisco Identity Services Engine (ISE) products running Release 1.4, 2.0, 2.0.1, 2.1.0: ISE, ISE Express, ISE Virtual Appliance. Cisco Bug IDs: CSCve74916.
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Analysis
by VulDB Data Team • 01/21/2021
The vulnerability identified as CVE-2017-12261 represents a critical privilege escalation flaw within the Cisco Identity Services Engine (ISE) platform that operates at the restricted shell level accessible via Secure Shell protocol. This security weakness specifically targets the input validation mechanisms implemented within the command line interface of the ISE system, creating a pathway for authenticated local attackers to bypass intended security restrictions and execute arbitrary commands with elevated privileges. The vulnerability resides in the restricted shell environment where user inputs are not adequately sanitized or validated before processing, allowing malicious command sequences to be interpreted and executed with higher privilege levels than initially permitted. The affected products include various releases of Cisco ISE, ISE Express, and ISE Virtual Appliance running versions 1.4, 2.0, 2.0.1, and 2.1.0, indicating a widespread impact across multiple deployment scenarios and configurations.
The technical exploitation of this vulnerability stems from incomplete input validation procedures within the restricted shell environment, which fails to properly sanitize user inputs before executing CLI commands. This incomplete validation creates a condition where maliciously crafted input sequences can be processed by the system's command interpreter, potentially allowing attackers to inject commands that would normally be restricted or filtered out. The vulnerability specifically affects the authentication and authorization mechanisms within the restricted shell context, where legitimate user credentials are required to establish access but are subsequently insufficient to prevent privilege escalation once inside the system. The flaw essentially allows an attacker who has already authenticated to the device to escalate their privileges and execute commands that would otherwise be restricted to administrative users or system processes. This represents a classic privilege escalation vulnerability where the system's intended access controls are bypassed through inadequate input sanitization.
The operational impact of CVE-2017-12261 extends beyond simple unauthorized command execution, as it provides attackers with the capability to gain elevated privileges and potentially compromise the entire ISE infrastructure. An attacker who successfully exploits this vulnerability could access sensitive network authentication data, modify user access policies, disable security features, or even gain access to underlying network devices managed by the ISE platform. The restricted shell environment, which is designed to limit user capabilities and prevent unauthorized access to critical system functions, becomes ineffective due to this flaw. This vulnerability could enable attackers to establish persistent access to the network infrastructure, manipulate authentication decisions, or disrupt critical network services that depend on the ISE platform for identity management and access control. The potential for lateral movement within the network increases significantly as attackers can leverage the elevated privileges to access other systems that rely on ISE for authentication services.
Organizations affected by this vulnerability should implement immediate mitigation strategies including applying the relevant Cisco security patches and updates that address the input validation issues within the restricted shell environment. The remediation process requires careful consideration of the specific ISE versions in use, as different releases may require different patching approaches and compatibility considerations. Network administrators should also implement additional monitoring and logging controls to detect unauthorized access attempts or suspicious command execution patterns within the ISE environment. The vulnerability aligns with CWE-20, which describes improper input validation as a fundamental weakness in software security that can lead to various attack vectors including privilege escalation. From an adversarial perspective, this vulnerability maps to ATT&CK technique T1068, which covers privilege escalation through the exploitation of system vulnerabilities, and T1078, which addresses legitimate credentials usage for persistence and access. Organizations should conduct comprehensive security assessments to identify all instances of affected ISE deployments and ensure that proper access controls and monitoring mechanisms are in place to detect and prevent exploitation attempts. The vulnerability underscores the critical importance of proper input validation and privilege separation in security-critical systems, particularly those handling identity and access management functions within enterprise networks.