CVE-2011-3285 in ASA
Summary
by MITRE
CRLF injection vulnerability in /+CSCOE+/logon.html on Cisco Adaptive Security Appliances (ASA) 5500 series devices with software 8.0 through 8.4 allows remote attackers to inject arbitrary HTTP headers and conduct HTTP response splitting attacks via unspecified vectors, aka Bug ID CSCth63101.
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Analysis
by VulDB Data Team • 12/01/2021
The CVE-2011-3285 vulnerability represents a critical CRLF injection flaw in Cisco Adaptive Security Appliances (ASA) 5500 series devices running software versions 8.0 through 8.4. This vulnerability specifically affects the /+CSCOE+/logon.html web interface component, which serves as the primary authentication portal for administrators to access the ASA management interface. The vulnerability stems from inadequate input validation and sanitization within the web application layer of the ASA software, creating a pathway for remote attackers to manipulate HTTP response headers through carefully crafted malicious input.
The technical exploitation of this vulnerability occurs through the manipulation of CRLF (Carriage Return Line Feed) sequences within HTTP headers, allowing attackers to inject arbitrary HTTP headers into the response stream. This injection capability enables attackers to perform HTTP response splitting attacks by inserting malicious headers that can redirect users to malicious websites or inject malicious content into web responses. The vulnerability exists because the ASA software fails to properly sanitize user-supplied input before incorporating it into HTTP response headers, creating a direct injection vector that bypasses normal security controls.
The operational impact of this vulnerability is significant as it provides remote attackers with the ability to manipulate web responses without requiring authentication to the ASA device itself. Attackers can leverage this vulnerability to conduct session hijacking attacks, redirect users to phishing sites, or inject malicious content into legitimate web responses. The vulnerability affects the web-based management interface of the ASA, which means that any user who accesses the device's management portal could potentially be exposed to these attacks. This creates a risk for network administrators who may inadvertently access compromised web responses or for attackers who can leverage the vulnerability to escalate privileges within the network infrastructure.
Security professionals should note that this vulnerability aligns with CWE-113, which describes improper neutralization of CRLF characters in HTTP headers, and maps to ATT&CK techniques such as T1566 for credential access and T1071 for application layer protocol usage. The vulnerability demonstrates the importance of input validation and output encoding in web applications, particularly in network infrastructure devices that handle authentication and management functions. Organizations should implement immediate mitigations including patching affected devices to software versions that address the vulnerability, implementing network segmentation to limit access to management interfaces, and monitoring for suspicious HTTP traffic patterns that may indicate exploitation attempts.
The remediation approach requires organizations to upgrade their Cisco ASA 5500 series devices to software versions that have been patched to address the CRLF injection vulnerability. Cisco released security advisories and patches for this vulnerability, and organizations should consult the official Cisco security bulletins for specific version requirements and installation procedures. Network administrators should also consider implementing additional security controls such as web application firewalls, monitoring for unusual HTTP header patterns, and restricting access to management interfaces through network access control lists to minimize the attack surface and reduce the risk of exploitation.