CVE-2005-3430 in MailSite Express
Summary
by MITRE
Incomplete blacklist vulnerability in Rockliffe MailSite Express before 6.1.22 allows remote attackers to upload and execute arbitrary script files by giving the files specific extensions, such as (1) .unk, (2) .asa, and possibly (3) .htr and (4) .aspx, which are not filtered like the .asp extension.
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Analysis
by VulDB Data Team • 06/24/2018
The vulnerability described in CVE-2005-3430 represents a critical incomplete blacklist security flaw within Rockliffe MailSite Express version 6.1.22 and earlier. This issue stems from the software's inadequate filtering mechanisms that fail to properly block all potentially dangerous file extensions from being uploaded and executed within the mail server environment. The vulnerability specifically affects the file upload validation process where the system maintains a blacklist of file extensions that should be rejected, but this list is incomplete and does not account for all script execution extensions that could be exploited by malicious actors.
The technical exploitation of this vulnerability relies on the fact that certain file extensions commonly used for web scripting and server-side execution are not included in the software's filtering rules. Extensions such as .unk, .asa, .htr, and .aspx are not properly blocked by the application's security controls, allowing attackers to upload malicious files with these extensions. The .asa extension is particularly significant as it is used by Microsoft Internet Information Services for active server pages, while .htr files are used for HTML server-side includes in IIS environments. The .aspx extension represents Microsoft's ASP.NET page execution format, all of which can execute code on the server when processed by the web server component.
This vulnerability creates a severe operational impact as it allows remote attackers to execute arbitrary code on the target system without requiring authentication or privileged access. The attack vector is straightforward - an attacker simply needs to upload a malicious file with one of the permitted extensions and then access it through the web interface, potentially leading to complete system compromise. The vulnerability demonstrates poor input validation and security by design flaws in the application's file handling mechanism, which directly violates fundamental security principles outlined in the CWE-20 category for Improper Input Validation. The incomplete blacklist approach creates a false sense of security, as attackers can easily discover and exploit the gaps in the filtering rules through simple experimentation.
The security implications extend beyond simple code execution to include potential privilege escalation, data exfiltration, and system persistence mechanisms. Attackers could upload web shells or backdoor scripts that would allow them to maintain long-term access to the compromised system, making this vulnerability particularly dangerous in enterprise environments where mail servers often contain sensitive organizational data. The vulnerability's exploitation aligns with several ATT&CK techniques including T1190 for Exploit Public-Facing Application and T1059 for Command and Scripting Interpreter, as it enables attackers to execute malicious scripts and commands on the target system. Organizations should consider implementing multiple layers of defense including network segmentation, web application firewalls, and comprehensive file type validation to mitigate this risk, as the vulnerability demonstrates the critical importance of maintaining complete and up-to-date security policies rather than relying on incomplete protection mechanisms.