CVE-2021-26293 in Aurora
Summary
by MITRE • 03/05/2021
An issue was discovered in AfterLogic Aurora through 8.5.3 and WebMail Pro through 8.5.3, when DAV is enabled. They allow directory traversal to create new files (such as an executable file under the web root). This is related to DAVServer.php in 8.x and DAV/Server.php in 7.x.
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Analysis
by VulDB Data Team • 03/28/2021
This vulnerability exists in AfterLogic Aurora and WebMail Pro email applications versions 8.5.3 and earlier, specifically when the WebDAV (DAV) functionality is enabled. The issue stems from inadequate input validation and path handling within the DAV server implementation, creating a directory traversal condition that allows remote attackers to manipulate file system operations. The vulnerability is particularly concerning because it enables attackers to create arbitrary files in the web root directory, potentially including executable files that could be leveraged for further compromise. The flaw is present in DAVServer.php for version 8.x and DAV/Server.php for version 7.x, indicating a persistent issue across multiple versions of the software.
The technical exploitation of this vulnerability occurs through crafted WebDAV requests that manipulate path traversal sequences, allowing attackers to bypass normal file system access controls. When DAV is enabled, the application processes file creation requests without proper sanitization of the requested file paths, enabling attackers to specify absolute paths or traverse directories to place malicious files in sensitive locations. This directory traversal vulnerability specifically affects the file creation functionality within the WebDAV implementation, where the application fails to validate or normalize file paths before executing file system operations. The vulnerability can be classified under CWE-22 as a directory traversal attack, which is a well-known weakness in web applications that allows unauthorized access to files outside the intended directory structure.
The operational impact of this vulnerability is significant as it provides attackers with the capability to execute arbitrary code on the affected server. By creating executable files in the web root directory, an attacker could potentially deploy web shells, backdoors, or other malicious payloads that would be accessible through the web server. This vulnerability essentially allows for remote code execution, which represents a critical security risk for any email server that has DAV enabled. The attack vector is particularly dangerous because it requires minimal privileges to exploit and can be automated, making it attractive to threat actors seeking persistent access to compromised systems. The vulnerability affects organizations that rely on these email applications for business communications, potentially exposing sensitive data and enabling further lateral movement within compromised networks.
Organizations should immediately disable DAV functionality in AfterLogic Aurora and WebMail Pro installations until proper patches are applied. The recommended mitigation strategy involves applying the latest security updates from AfterLogic, which address the directory traversal vulnerability in the DAV server implementation. System administrators should also implement network segmentation and access controls to limit exposure of affected services to untrusted networks. Additionally, monitoring for suspicious file creation activities in web root directories should be enabled, particularly for executable files or files with unusual extensions. The vulnerability aligns with ATT&CK technique T1059.007 for command and script interpreter execution, as the ability to create executable files enables malicious code deployment. Organizations should also consider implementing web application firewalls to detect and block malicious WebDAV requests, and conduct regular security assessments to identify similar path traversal vulnerabilities in other web applications.