CVE-2003-1582 in IIS
Summary
by MITRE
Microsoft Internet Information Services (IIS) 6.0, when DNS resolution is enabled for client IP addresses, allows remote attackers to inject arbitrary text into log files via an HTTP request in conjunction with a crafted DNS response, as demonstrated by injecting XSS sequences, related to an "Inverse Lookup Log Corruption (ILLC)" issue.
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Analysis
by VulDB Data Team • 04/30/2026
The vulnerability described in CVE-2003-1582 represents a critical security flaw in Microsoft Internet Information Services version 6.0 that exploits the interaction between DNS resolution and web server logging mechanisms. This issue specifically affects systems where IIS 6.0 is configured to perform reverse DNS lookups on client IP addresses, creating an attack surface that adversaries can leverage to manipulate server log files through carefully crafted network responses. The flaw enables remote attackers to inject arbitrary text into the web server's log files, potentially allowing for cross-site scripting attacks when log files are subsequently viewed by administrators or automated systems. This vulnerability operates through a sophisticated attack chain that combines network-level manipulation with application-level logging behavior, making it particularly dangerous in enterprise environments where log monitoring and analysis are critical security controls.
The technical implementation of this vulnerability stems from the way IIS 6.0 handles inverse DNS lookups when processing HTTP requests. When DNS resolution is enabled for client IP addresses, the web server performs a reverse DNS query to resolve the client's IP address to a hostname. The flaw occurs because IIS does not properly sanitize or validate the DNS response data before incorporating it into log files. Attackers can manipulate DNS responses to include malicious content such as XSS sequences, which then get embedded into the log files during the logging process. This creates a persistent attack vector where malicious code can be stored in the server's logs and executed when administrators or security tools view these log files, effectively transforming the logging infrastructure itself into an attack platform. The vulnerability specifically relates to CWE-117, which addresses improper output neutralization for logs, and demonstrates how seemingly benign logging functionality can become a security risk when input validation is inadequate. The attack requires the attacker to control or influence DNS responses, which can be achieved through DNS cache poisoning, man-in-the-middle attacks, or by compromising DNS servers within the network infrastructure.
The operational impact of this vulnerability extends beyond simple log file corruption, as it can facilitate more sophisticated attacks that leverage the logging infrastructure itself. When administrators or security monitoring tools access log files containing injected malicious content, they inadvertently execute the embedded XSS payloads, potentially compromising their systems or allowing attackers to gain additional privileges. This creates a significant risk in environments where log files are regularly reviewed by security personnel or where automated log analysis systems parse log content for threat detection. The vulnerability is particularly concerning in large enterprise environments where IIS servers are extensively logged and where log files are shared across multiple systems or integrated with security information and event management (SIEM) solutions. The attack can remain undetected for extended periods since the malicious content is embedded within legitimate-looking log entries, making it difficult for security teams to identify compromised systems through traditional log analysis methods. This vulnerability also impacts the integrity of security audit trails and forensic investigations, as compromised log files can no longer be trusted as accurate representations of system activity.
Organizations should implement multiple layers of defense to mitigate this vulnerability, beginning with disabling reverse DNS lookups in IIS 6.0 when they are not required for legitimate business purposes. The most effective immediate mitigation involves configuring IIS to disable DNS resolution for client IP addresses in the logging process, which prevents the injection of malicious content through DNS manipulation. Security administrators should also implement proper log file validation and sanitization processes that can detect and remove suspicious content from log files before they are analyzed or stored. Additionally, network segmentation and DNS security measures such as DNSSEC implementation can help prevent DNS cache poisoning attacks that are commonly used to exploit this vulnerability. Organizations should also consider implementing network monitoring solutions that can detect anomalous DNS response patterns and alert security teams to potential attacks targeting this specific vulnerability. The ATT&CK framework categorizes this type of attack under T1070.002 for "Indicator Removal on Host: File Deletion" and T1566.002 for "Phishing: Spearphishing Attachment" when considering how attackers might use compromised logging systems to deliver malicious payloads to system administrators. Regular security assessments and vulnerability scanning should include checks for this specific configuration issue, and organizations should maintain updated security patches and configuration baselines to prevent exploitation of this and similar logging-related vulnerabilities.