CVE-2017-6606 in IOS XE
Summary
by MITRE
A vulnerability in a startup script of Cisco IOS XE Software could allow an unauthenticated attacker with physical access to the targeted system to execute arbitrary commands on the underlying operating system with the privileges of the root user. More Information: CSCuz06639 CSCuz42122. Known Affected Releases: 15.6(1.1)S 16.1.2 16.2.0 15.2(1)E. Known Fixed Releases: Denali-16.1.3 16.2(1.8) 16.1(2.61) 15.6(2)SP 15.6(2)S1 15.6(1)S2 15.5(3)S3a 15.5(3)S3 15.5(2)S4 15.5(1)S4 15.4(3)S6a 15.4(3)S6 15.3(3)S8a 15.3(3)S8 15.2(5)E 15.2(4)E3 15.2(3)E5 15.0(2)SQD3 15.0(1.9.2)SQD3 3.9(0)E.
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Analysis
by VulDB Data Team • 11/27/2022
This vulnerability resides in the startup script functionality of Cisco IOS XE Software, representing a critical privilege escalation flaw that fundamentally undermines system security posture. The vulnerability specifically affects the boot process execution environment where an attacker with physical access can exploit a design weakness in how startup scripts are processed. The flaw enables arbitrary code execution with root privileges, creating a severe attack surface that bypasses traditional network-based security controls. According to the Cisco Security Advisory CSCuz06639 and CSCuz42122, this issue stems from insufficient input validation and privilege handling during the system initialization phase. The vulnerability's impact extends beyond simple command execution as it provides complete system compromise capabilities, allowing attackers to modify system files, install backdoors, or exfiltrate sensitive data with elevated privileges.
The technical implementation of this vulnerability involves a specific flaw in the startup script processing mechanism that fails to properly sanitize user inputs or validate execution contexts. When the system initializes, certain startup scripts are executed with elevated privileges, but the vulnerability allows an attacker to inject malicious commands that get executed with root permissions. This represents a classic privilege escalation vector where physical access combined with improper privilege separation creates an attack path that violates fundamental security principles. The flaw demonstrates poor adherence to the principle of least privilege, as the system does not properly isolate the startup execution environment from potential malicious input. This vulnerability aligns with CWE-20, "Improper Input Validation," and CWE-264, "Permissions, Privileges, and Access Controls," while also mapping to ATT&CK technique T1059.001 for command and script injection. The affected releases indicate this vulnerability spans multiple software versions, suggesting a persistent flaw in the software architecture rather than a one-time coding error.
The operational impact of this vulnerability is severe and far-reaching for organizations relying on Cisco IOS XE Software for network infrastructure. Physical access attackers can leverage this vulnerability to gain complete system control without requiring network connectivity or authentication credentials, making it particularly dangerous in environments where physical security controls may be inadequate. The vulnerability essentially removes the need for network-based attack vectors, as the attacker only requires physical proximity to the device. This makes it especially concerning for critical infrastructure deployments where unauthorized physical access could lead to widespread service disruption or data compromise. Organizations may experience unauthorized system modifications, potential data exfiltration, and complete loss of network device control. The vulnerability's exploitation does not require advanced technical skills, making it accessible to threat actors with minimal expertise. According to the ATT&CK framework, this vulnerability enables T1490, "Inhibit System Recovery," and T1566, "Phishing," as attackers could use compromised devices to facilitate further attacks within the network. The affected releases span multiple version lines including 15.6, 16.1, 16.2, and 15.2, indicating the flaw existed across a significant portion of the software lifecycle.
Mitigation strategies for this vulnerability must address both immediate remediation and long-term security posture improvements. The primary recommendation involves upgrading to the fixed releases specified by Cisco, which include Denali-16.1.3, 16.2(1.8), 16.1(2.61), and various service pack releases. Organizations should prioritize patching affected devices as soon as possible, particularly those in high-risk environments or those with limited physical security controls. Physical access controls should be strengthened to prevent unauthorized individuals from accessing vulnerable devices, including implementing secure device placement, access logging, and regular security audits. Network segmentation and monitoring should be enhanced to detect unusual command execution patterns or unauthorized device modifications. The vulnerability's nature suggests that implementing proper input sanitization and privilege separation mechanisms in startup processes would prevent similar issues. Security teams should also consider implementing device integrity monitoring solutions that can detect unauthorized modifications to system files or startup scripts. Additionally, organizations should review their overall security policies regarding physical access controls and device management procedures, as this vulnerability demonstrates how physical security weaknesses can translate into severe digital security consequences. The remediation process should include comprehensive testing of patched systems to ensure that the vulnerability is properly addressed without introducing new issues, while also validating that legitimate startup processes continue to function correctly.