CVE-2008-2686 in Flux CMS
Summary
by MITRE
webinc/bxe/scripts/loadsave.php in Flux CMS 1.5.0 and earlier allows remote attackers to execute arbitrary code by overwriting a PHP file in webinc/bxe/scripts/ via a filename in the XML parameter and PHP sequences in the request body, then making a direct request for this filename.
Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.
Analysis
by VulDB Data Team • 10/27/2024
This vulnerability exists in Flux CMS version 1.5.0 and earlier where the webinc/bxe/scripts/loadsave.php script fails to properly validate user input when processing XML data. The flaw allows remote attackers to perform arbitrary code execution by manipulating the XML parameter to specify a target PHP file within the webinc/bxe/scripts/ directory. When an attacker crafts a malicious request containing PHP code sequences in the body and specifies a filename in the XML parameter, the system processes this input without adequate sanitization, enabling the attacker to overwrite existing PHP files with malicious content. The vulnerability stems from improper input validation and inadequate file handling mechanisms that permit arbitrary file operations in a web-accessible directory. This represents a classic file inclusion vulnerability that falls under CWE-94, which describes the execution of arbitrary code due to insufficient input validation. The attack vector is particularly dangerous as it allows attackers to directly overwrite critical system files, potentially leading to complete system compromise. The vulnerability is further exacerbated by the fact that the target directory is web-accessible, meaning that once a malicious file is written, it can be executed directly through HTTP requests, making it an ideal candidate for persistent backdoor deployment.
The operational impact of this vulnerability extends beyond simple code execution to encompass full system compromise and persistent access. An attacker who successfully exploits this vulnerability can gain the ability to upload malicious PHP scripts that execute with the privileges of the web server, potentially allowing for data exfiltration, system enumeration, and further lateral movement within the network. The vulnerability allows for the creation of backdoors that can persist across system reboots, as the malicious files remain in the web-accessible directory structure. This type of vulnerability aligns with ATT&CK technique T1505.003 for "Web Shell" and T1059.007 for "Command and Scripting Interpreter: PowerShell" as it provides a mechanism for attackers to establish persistent access. The attack chain typically involves initial exploitation through the XML parameter manipulation followed by direct HTTP requests to execute the malicious PHP code, which can then be used to establish reverse shells or perform additional malicious activities.
Mitigation strategies for this vulnerability must address both the immediate code execution risk and the underlying architectural flaws that enabled the exploitation. Organizations should immediately upgrade to Flux CMS version 1.5.1 or later where this vulnerability has been patched through proper input validation and file handling mechanisms. The fix involves implementing strict validation of filenames in XML parameters, ensuring that only pre-approved file paths and extensions are accepted. Additionally, implementing proper access controls through web server configuration to restrict direct execution of PHP files in the webinc/bxe/scripts/ directory would significantly reduce the attack surface. Network segmentation and firewall rules should be configured to limit access to the vulnerable directory structure. The implementation of web application firewalls with signature-based detection for suspicious XML parameter patterns and PHP code sequences would provide additional defense layers. Regular security audits of file permissions and directory access controls should be conducted to prevent unauthorized file creation and modification. Organizations should also implement proper input sanitization techniques including the use of allowlists for valid filenames and character sets, as well as the principle of least privilege for web server accounts to minimize the potential impact of successful exploitation.