CVE-2021-42669 is a critical file upload vulnerability affecting the Engineers Online Portal. This vulnerability allows attackers to upload a PHP web shell through the avatar upload functionality, ultimately enabling remote command execution on the server. The vulnerability is classified as critical with a CVSS score of 9.8, indicating a severe risk to organizations.
The vulnerability exists in the dashboard_teacher.php file, which allows users to change their avatars via teacher_avatar.php. Uploads are stored in the /admin/uploads/ directory, making them accessible to all users. An attacker could exploit this by uploading a malicious PHP file that executes system commands on the server.
Risk to organizations includes unauthorized access to sensitive information and potential server compromise, as attackers may execute arbitrary commands through the uploaded web shell. Given the criticality of this vulnerability, organizations must prioritize patching immediately.
The vulnerability was published on November 5, 2021. While it has been modified since its initial discovery, the urgency for remediation remains high due to its severe impact and the potential for exploitation.
Vulnerability Details
CVE-2021-42669 is characterized as a file upload vulnerability, which allows an attacker to upload arbitrary files to the server. The CVSS score is 9.8, reflecting its critical severity level, primarily due to the high impact on confidentiality, integrity, and availability. The affected product is the Engineers Online Portal, developed by Engineers Online Portal Project. The CWE classification for this vulnerability is CWE-434, indicating unrestricted file upload.
Technical Analysis
The root cause of CVE-2021-42669 lies in the lack of proper validation and restrictions on file uploads. Attackers can exploit this vulnerability by uploading a PHP web shell to the server through a seemingly innocuous functionality meant for avatar updates.
The attack vector is network-based, requiring low attack complexity as no special privileges or user interaction is needed. This makes the vulnerability particularly dangerous. The uploaded files are stored in a publicly accessible directory, which allows attackers to execute commands by accessing the web shell directly.
Confidentiality, integrity, and availability are all significantly impacted, as an attacker can access sensitive data, manipulate files, and disrupt service availability.
Risk & Impact Analysis
The real-world deployment risk associated with CVE-2021-42669 is substantial. Organizations utilizing the Engineers Online Portal may face severe consequences, including unauthorized access to sensitive information, data breaches, and service disruptions.
Given its critical CVSS score of 9.8 and its potential for exploitation, organizations should address this vulnerability in their priority patch cycle to mitigate risks effectively. The urgency for remediation is further emphasized by the high percentile score of the EPSS, indicating a significant probability of active exploitation in the wild.
Exploitation Status
Signal | Status |
|---|---|
Known Exploit | Yes |
Public PoC | Yes |
Actively Exploited | No |
Ransomware Use | No |
Affected Versions
The vulnerability affects all versions of the Engineers Online Portal prior to the vendor's patch. Organizations should verify their version and apply the necessary updates.
Mitigation & Remediation
Organizations should prioritize patching the Engineers Online Portal to address CVE-2021-42669. The vendor's patch should be applied immediately to mitigate risks associated with this vulnerability. In cases where patching is not immediately feasible, consider implementing the following workarounds:
1. Restrict file uploads to only allow specific file types, such as images, and validate file content.
2. Configure proper permissions on the /admin/uploads/ directory to prevent unauthorized access.
3. Monitor uploads and server logs for any suspicious activity.
Continuous penetration testing can also help validate the effectiveness of security measures put in place.
Detection Guidance
Organizations should monitor their systems for the following indicators of compromise:
1. Unusual file uploads in the /admin/uploads/ directory.
2. Unexpected changes to user avatars or user permissions.
3. Logs indicating the execution of unexpected commands.
AppSecure Threat Intelligence Insight
CVE-2021-42669 highlights the importance of secure file handling within web applications. The vulnerability exemplifies a common attack vector where improper input validation leads to remote code execution. Security teams should learn from this incident to enhance file upload mechanisms, ensuring they incorporate strict validation and monitoring.
Organizations should consider implementing a comprehensive vulnerability management program to identify and remediate similar weaknesses proactively.
Long-term, organizations should foster a culture of security awareness among developers and implement practices such as penetration testing to continuously assess and improve their security posture.
By learning from vulnerabilities like CVE-2021-42669, organizations can better defend against future threats and safeguard their digital assets.
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
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