CVE-2008-5430 in Thunderbird
Summary
by MITRE
Mozilla Thunderbird 2.0.14 does not properly handle (1) multipart/mixed e-mail messages with many MIME parts and possibly (2) e-mail messages with many "Content-type: message/rfc822;" headers, which might allow remote attackers to cause a denial of service (stack consumption or other resource consumption) via a large e-mail message, a related issue to CVE-2006-1173.
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Analysis
by VulDB Data Team • 10/22/2018
The vulnerability described in CVE-2008-5430 represents a significant denial of service weakness in Mozilla Thunderbird version 2.0.14 that stems from inadequate handling of complex email message structures. This flaw specifically targets the email client's processing of multipart/mixed email messages containing numerous MIME parts and messages with excessive "Content-type: message/rfc822;" headers. The issue constitutes a classic resource exhaustion attack vector where maliciously crafted emails can trigger excessive memory consumption or stack overflow conditions within the email client's parsing mechanisms. The vulnerability operates by exploiting the client's insufficient bounds checking and memory management when processing these particular email formats, creating a scenario where legitimate email processing becomes computationally expensive and resource-intensive.
The technical implementation of this vulnerability involves the email client's failure to properly validate or limit the number of MIME parts within multipart messages or the count of rfc822 content-type headers in a single email. When Thunderbird encounters an email message with an excessive number of these components, its internal parsing algorithms consume disproportionate amounts of stack memory or heap resources. This behavior aligns with CWE-129, which addresses improper validation of array indices and resource limits, and CWE-400, which covers unspecified resource exhaustion conditions. The flaw essentially creates a scenario where the email client's memory management system becomes overwhelmed during message parsing, leading to application instability or complete crash conditions.
From an operational perspective, this vulnerability presents a substantial risk to organizations relying on Thunderbird for email communication, as it can be exploited through simple email delivery without requiring user interaction beyond opening the malicious message. Attackers can construct email messages with thousands of MIME parts or nested rfc822 headers that cause the client to consume excessive system resources, potentially leading to system-wide performance degradation or complete application failure. The impact extends beyond individual user experience to potential organizational disruption, as multiple users receiving such messages simultaneously could overwhelm system resources. This vulnerability directly relates to the ATT&CK technique T1499.004, which covers network denial of service attacks through resource exhaustion, and represents a common pattern in email client security where parsing vulnerabilities lead to system instability.
The mitigation strategies for this vulnerability should focus on both immediate defensive measures and long-term architectural improvements. Organizations should implement email filtering solutions that can detect and block messages with suspiciously high numbers of MIME parts or rfc822 headers before they reach end-user inboxes. Additionally, upgrading to newer versions of Thunderbird where these parsing issues have been addressed provides the most effective long-term solution. The fix typically involves implementing proper bounds checking on the number of MIME parts processed, establishing reasonable limits on header counts, and improving memory management during email parsing operations. Security administrators should also consider implementing email size limits and content analysis rules that can identify potentially malicious email structures before they can cause resource exhaustion attacks.