CVE-2002-2313 in Eudora
Summary
by MITRE
Eudora email client 5.1.1, with "use Microsoft viewer" enabled, allows remote attackers to execute arbitrary programs via an HTML email message containing a META refresh tag that references an embedded .mhtml file with ActiveX controls that execute a second embedded program, which is processed by Internet Explorer.
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Analysis
by VulDB Data Team • 01/21/2019
This vulnerability exists in Eudora email client version 5.1.1 when the "use Microsoft viewer" feature is enabled, creating a dangerous chain of execution that can be exploited by remote attackers. The flaw leverages the client's handling of HTML email messages and its integration with Internet Explorer's rendering engine to execute arbitrary code on vulnerable systems. The attack vector involves a specially crafted HTML email that contains a META refresh tag directing the client to process an embedded .mhtml file. This .mhtml file contains ActiveX controls that are designed to execute a second embedded program, effectively bypassing traditional email security measures by utilizing the trusted Internet Explorer rendering environment.
The technical implementation of this vulnerability exploits the trust relationship between Eudora and Internet Explorer, where the email client delegates HTML rendering to the browser component rather than processing content independently. When the META refresh tag is encountered, it triggers the automatic download and processing of the embedded .mhtml file, which contains malicious ActiveX components. These ActiveX controls are specifically crafted to execute additional payloads, creating a multi-stage attack that can escalate privileges or install malware on the target system. The vulnerability demonstrates a classic cross-application exploitation pattern where one application (Eudora) inadvertently enables another application (Internet Explorer) to execute malicious code through its integrated viewer functionality.
From an operational perspective, this vulnerability represents a significant security risk for users who have the Microsoft viewer enabled in their Eudora configuration, as it requires no special privileges or complex social engineering to exploit. The attack can be delivered through standard email communication channels, making it particularly dangerous in corporate environments where email is the primary communication medium. The exploit chain is relatively straightforward for attackers to implement, as it only requires crafting an HTML email with specific META refresh and embedded content elements that leverage existing browser capabilities. This vulnerability falls under the CWE-74 standard for Improper Neutralization of Special Elements in Output Used by a Downstream Component, specifically in the context of HTML injection and cross-application code execution.
The attack pattern aligns with several ATT&CK techniques including T1203 - Exploitation for Client Execution and T1059 - Command and Scripting Interpreter, as the vulnerability enables execution of arbitrary programs through legitimate email client functionality. Organizations using Eudora 5.1.1 with the Microsoft viewer enabled should implement immediate mitigations including disabling the "use Microsoft viewer" option, updating to newer versions of the email client, and implementing email content filtering that blocks META refresh tags and embedded ActiveX controls. Network-level protections should also be deployed to monitor for suspicious email content patterns that may indicate attempts to exploit this vulnerability, particularly focusing on .mhtml file attachments and embedded HTML content with refresh directives that could trigger the malicious execution chain.