CVE-2023-20186 in IOS
Summary
by MITRE • 10/25/2023
A vulnerability in the Authentication, Authorization, and Accounting (AAA) feature of Cisco IOS Software and Cisco IOS XE Software could allow an authenticated, remote attacker to bypass command authorization and copy files to or from the file system of an affected device using the Secure Copy Protocol (SCP).
This vulnerability is due to incorrect processing of SCP commands in AAA command authorization checks. An attacker with valid credentials and level 15 privileges could exploit this vulnerability by using SCP to connect to an affected device from an external machine. A successful exploit could allow the attacker to obtain or change the configuration of the affected device and put files on or retrieve files from the affected device.
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Analysis
by VulDB Data Team • 10/25/2023
This vulnerability resides within the authentication, authorization, and accounting framework of Cisco's networking software, specifically affecting both IOS and IOS XE operating systems. The flaw manifests in the AAA command authorization mechanism where the system fails to properly validate SCP commands, creating a bypass opportunity for authenticated attackers. The vulnerability represents a critical weakness in Cisco's privilege management system, where legitimate administrative access does not properly enforce the security boundaries that should prevent unauthorized file operations. This issue directly impacts the integrity and confidentiality of network device configurations and stored data, as it allows attackers to manipulate the device's file system through standard network protocols.
The technical implementation of this vulnerability stems from improper handling of Secure Copy Protocol commands within the AAA authorization framework. When an authenticated user with level 15 privileges attempts to establish an SCP connection to an affected device, the system's command authorization checks fail to properly validate whether the user should be permitted to perform file system operations through SCP. This processing error creates a gap in the authorization chain that allows attackers to execute file operations that should be restricted. The flaw essentially permits an attacker to circumvent the normal command authorization flow that would typically prevent file system modifications or transfers, effectively elevating their operational capabilities beyond what their assigned privileges should allow.
The operational impact of this vulnerability extends beyond simple privilege escalation, as it provides attackers with the capability to manipulate critical network infrastructure components. An attacker who successfully exploits this vulnerability can copy files to and from the device's file system, potentially allowing them to extract sensitive configuration data, install malicious software, or modify device behavior. This capability represents a significant threat to network security, as it allows adversaries to compromise the integrity of network devices and potentially use them as stepping stones for further attacks. The vulnerability's remote nature means that attackers do not require physical access to the device, making it particularly dangerous in environments where network devices are accessible from external networks.
Organizations affected by this vulnerability should implement immediate mitigations to protect their network infrastructure. The primary recommendation involves applying the latest security patches provided by Cisco, which address the specific AAA authorization processing flaw. Network administrators should also consider implementing additional controls such as restricting SCP access to trusted network segments, implementing stricter access controls for level 15 accounts, and monitoring for unusual file system operations. From a cybersecurity perspective, this vulnerability aligns with CWE-284 (Improper Access Control) and could be categorized under ATT&CK technique T1566 (Phishing) if attackers initially gain access through social engineering before exploiting this specific authorization bypass. The vulnerability demonstrates the critical importance of proper authorization validation in network security systems and highlights the need for comprehensive security testing of authentication mechanisms.