CVE-2006-7027 in ISA Server
Summary
by MITRE
Microsoft Internet Security and Acceleration (ISA) Server 2004 logs unusual ASCII characters in the Host header, including the tab, which allows remote attackers to manipulate portions of the log file and possibly leverage this for other attacks.
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Analysis
by VulDB Data Team • 10/14/2017
Microsoft Internet Security and Acceleration ISA Server 2004 contains a vulnerability in its logging mechanism that arises from insufficient input validation of the Host header field. The flaw specifically occurs when the server processes HTTP requests containing unusual ASCII characters, particularly tab characters, within the Host header. This vulnerability is categorized under CWE-181 as improper handling of data that could be used for injection attacks, and aligns with ATT&CK technique T1070.004 for Indicator Removal on Host. The vulnerability stems from the server's failure to properly sanitize or escape special characters during log file generation, creating a potential vector for log injection attacks.
The technical implementation of this flaw allows remote attackers to manipulate log file contents by crafting HTTP requests with tab characters in the Host header field. When the ISA Server processes these requests and logs them to its system files, the tab characters can cause unintended formatting within the log entries. This manipulation can disrupt log analysis tools that expect standard text formatting, potentially leading to incorrect parsing of log data and making it difficult to identify legitimate network activity. The vulnerability is particularly concerning because it affects the integrity of the logging infrastructure itself, which is critical for security monitoring and incident response operations.
The operational impact of this vulnerability extends beyond simple log manipulation, as it can be leveraged as a stepping stone for more sophisticated attacks. Attackers can potentially use the log injection capabilities to hide malicious activity within legitimate-looking log entries, making detection significantly more difficult. This type of attack falls under ATT&CK technique T1070.002 for Clear Windows Event Logs, where attackers manipulate system logs to avoid detection. Additionally, the vulnerability can be exploited in conjunction with other attacks that rely on log file analysis for their success, such as those targeting log parsing systems or forensic analysis tools.
Organizations should implement immediate mitigations including input validation for Host header fields, regular log file monitoring for unusual character sequences, and enhanced log parsing security measures. The recommended approach involves configuring ISA Server to reject or sanitize tab and other special characters in HTTP headers before logging. System administrators should also implement log integrity checking mechanisms and consider deploying additional monitoring solutions that can detect anomalous log patterns. According to industry best practices, this vulnerability demonstrates the importance of proper input sanitization as outlined in CWE-172 and aligns with defensive security measures recommended in NIST Special Publication 800-125 for secure logging practices. Regular security updates and patches should be applied to ensure the ISA Server environment remains protected against such vulnerabilities that could compromise the integrity of security monitoring systems.