CVE-2006-0544 in Internet Explorer
Summary
by MITRE
urlmon.dll in Microsoft Internet Explorer 7.0 beta 2 (aka 7.0.5296.0) allows remote attackers to cause a denial of service (application crash) and possibly execute arbitrary code via a BGSOUND element with its SRC attribute set to "file://" followed by a large number of "-" (dash of hyphen) characters.
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Analysis
by VulDB Data Team • 07/07/2021
The vulnerability identified as CVE-2006-0544 represents a critical security flaw within Microsoft Internet Explorer 7.0 beta 2, specifically within the urlmon.dll component that handles URL moniker operations. This issue manifests through the improper handling of BGSOUND elements in HTML documents, creating a pathway for remote attackers to exploit the browser's processing mechanisms. The vulnerability is particularly concerning as it can lead to both denial of service conditions and potential arbitrary code execution, making it a significant threat to user security and system integrity.
The technical flaw occurs when Internet Explorer encounters a BGSOUND element with its SRC attribute pointing to a file:// URL followed by an excessive number of dash characters. This specific construction triggers a buffer overflow condition within the urlmon.dll library, where the application fails to properly validate the length and composition of the URL parameter. The vulnerability stems from inadequate input sanitization and bounds checking mechanisms within the browser's HTML parsing engine, allowing maliciously crafted URLs to cause memory corruption. The use of file:// protocol combined with excessive hyphen characters creates a scenario where the application's internal buffer management fails to handle the malformed input properly, leading to unpredictable behavior.
From an operational perspective, this vulnerability presents a severe risk to enterprise environments where users may inadvertently encounter malicious web content. The remote exploitation capability means that attackers can deliver malicious payloads through web pages without requiring local system access, making it particularly dangerous in corporate networks. The potential for arbitrary code execution transforms this denial of service vulnerability into a full compromise vector, allowing attackers to execute malicious code with the privileges of the affected user. This vulnerability could be leveraged in phishing attacks, drive-by downloads, or as part of multi-stage attack campaigns, making it a valuable target for threat actors seeking to establish persistent access to systems.
The impact of this vulnerability aligns with CWE-121, which describes heap-based buffer overflow conditions, and demonstrates characteristics consistent with ATT&CK technique T1203, involving exploitation of remote services through web-based attacks. Organizations should implement immediate mitigations including disabling the BGSOUND element processing, applying security patches from Microsoft, and implementing network-based restrictions to prevent access to potentially malicious web content. Additionally, browser hardening measures such as disabling automatic execution of embedded content and implementing strict content security policies can help reduce the attack surface. Security monitoring should focus on detecting unusual network traffic patterns and potential exploitation attempts targeting this specific vulnerability, as the malicious HTML constructs may be detected through web application firewalls or intrusion detection systems configured to identify such patterns.