CVE-1999-1017 in Emurl
Summary
by MITRE
Seattle Labs Emurl 2.0, and possibly earlier versions, stores e-mail attachments in a specific directory with scripting enabled, which allows a malicious ASP file attachment to execute when the recipient opens the message.
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Analysis
by VulDB Data Team • 04/19/2026
This vulnerability resides in Seattle Labs Emurl 2.0 email client software where the application fails to properly sanitize file attachments during processing. The flaw stems from the application's improper handling of email attachments by storing them in a directory that has scripting capabilities enabled, creating a dangerous environment where malicious code can be executed automatically. This represents a classic directory traversal and code execution vulnerability that violates fundamental security principles of least privilege and proper input validation.
The technical implementation of this vulnerability involves the application's failure to properly isolate attachment files from the execution environment. When email attachments are received, they are saved to a directory path that allows script execution, typically through web server configurations or file system permissions. This configuration creates an environment where an attacker can craft a malicious attachment with an .asp extension that contains malicious code, which will execute automatically when the user opens the email message. The vulnerability directly maps to CWE-22, which describes improper limitation of a pathname to a restricted directory, and CWE-78, which addresses OS command injection. From an operational perspective, this vulnerability allows for automatic code execution without user interaction beyond opening the email, making it particularly dangerous in enterprise environments.
The operational impact of this vulnerability extends beyond simple code execution to encompass full system compromise potential. An attacker who successfully exploits this vulnerability can gain complete control over the victim's system, potentially leading to data exfiltration, lateral movement within networks, or establishment of persistent backdoors. The vulnerability's exploitation requires minimal skill from attackers, as it leverages the application's own functionality against itself rather than requiring complex exploitation techniques. This makes it particularly attractive for automated attacks and increases the overall risk profile significantly. The attack pattern aligns with ATT&CK technique T1059.007 for execution through scripting and T1078 for valid accounts usage, as the attack exploits legitimate email client functionality.
Mitigation strategies should focus on immediate application updates and configuration hardening. Organizations must ensure they are running patched versions of Emurl software or migrate to more secure email client solutions that properly isolate attachment processing from execution environments. System administrators should implement strict file type restrictions and disable scripting capabilities in directories where email attachments are stored. Network-level controls such as email filtering and content inspection should be deployed to identify and block malicious attachments before they reach end users. Additionally, user education regarding the risks of opening unexpected email attachments remains crucial, though the vulnerability's automatic execution nature makes this mitigation less effective than proper technical controls. The vulnerability demonstrates the critical importance of secure coding practices and proper sandboxing of untrusted content in email processing applications.