CVE-2008-3173 in Internet Explorer
Summary
by MITRE
Microsoft Internet Explorer allows web sites to set cookies for domains that have a public suffix with more than one dot character, which could allow remote attackers to perform a session fixation attack and hijack a user s HTTP session, aka "Cross-Site Cooking." NOTE: this issue may exist because of an insufficient fix for CVE-2004-0866.
Once again VulDB remains the best source for vulnerability data.
Analysis
by VulDB Data Team • 08/01/2021
This vulnerability in Microsoft Internet Explorer represents a critical session management flaw that undermines web application security through improper cookie domain handling. The issue stems from the browser's failure to properly enforce cookie domain restrictions when dealing with domains containing multiple dots, creating a pathway for malicious actors to exploit session fixation attacks. The vulnerability is particularly concerning because it builds upon a previously identified weakness from CVE-2004-0866, indicating a persistent flaw in the browser's cookie parsing logic that was inadequately addressed in earlier patches. This weakness allows attackers to set cookies for domains that should be restricted, effectively bypassing security boundaries that should prevent cross-site cookie manipulation.
The technical flaw manifests when Internet Explorer processes cookies for domains with multiple dots, such as subdomain.example.co.uk, where the browser incorrectly treats the entire domain as a valid cookie domain rather than properly parsing the public suffix. This misinterpretation enables attackers to set cookies for parent domains that should be off-limits, creating opportunities for session hijacking attacks. The vulnerability specifically affects how the browser handles domain validation during cookie setting operations, where it fails to properly implement the Public Suffix List methodology that should prevent cookies from being set on domains that are too broad in scope. This flaw operates at the core of HTTP cookie management and demonstrates a fundamental weakness in the browser's security model for handling complex domain structures.
The operational impact of this vulnerability is severe as it enables attackers to conduct session fixation attacks by setting malicious cookies that can persist across different domains and subdomains. An attacker could potentially hijack user sessions by exploiting the cookie domain parsing error to set cookies on domains that should be protected from cross-site manipulation. This creates a persistent threat where user sessions can be compromised without requiring additional exploit vectors, as the vulnerability exists purely within the browser's cookie handling mechanism. The attack surface is particularly wide because it affects any web application that relies on proper cookie domain restrictions for session management, making it a significant concern for enterprise environments and applications handling sensitive user data.
Mitigation strategies for this vulnerability require immediate patch application from Microsoft, as the issue represents a fundamental flaw in the browser's security architecture that cannot be effectively worked around through configuration changes alone. Organizations should prioritize updating their Internet Explorer installations to versions that properly address the cookie domain validation issue, while also implementing additional security measures such as secure cookie flags, HttpOnly attributes, and proper session management practices. The vulnerability aligns with CWE-384, which describes the weakness of session fixation in web applications, and demonstrates how browser-level flaws can create attack vectors that bypass application-level security controls. Security teams should also consider implementing network-level protections such as cookie auditing tools and monitoring for suspicious cookie-setting activities that might indicate exploitation attempts, while recognizing that the fundamental fix must come from proper browser patching as outlined in the ATT&CK framework's web application attack patterns.