Incident Background

On the night of May 19, 2025, the web services team at Company A (anonymized for confidentiality) detected a major disruption: every file in a public download directory had suddenly become inaccessible. Believing it to be a system glitch, the team was preparing to begin standard troubleshooting procedures, focusing on server configurations.

At the same time, the Sangfor Athena MDR (Managed Detection and Response) team detected an unauthorized web shell that had been uploaded to the same web server and immediately notified Company A’s team (see Figure 1). This confirmed that the disruption was not a simple technical fault but the result of a more serious issue—an active cyberattack. The Sangfor Athena MDR team then promptly launched incident response procedures.

Sangfor Athena MDR notifies Company A of the cybersecurity event

Figure 1 - Sangfor Athena MDR notifies Company A of the cybersecurity event

The Issue: Unauthorized File Upload Vulnerability

Athena MDR analysis traced the root cause of the attack to an unauthenticated file upload vulnerability in an outdated script (see Figure 2). The attacker uploaded multiple malicious files in an attempt to exploit the vulnerability (see Figure 3), one of which successfully triggered a 500 Internal Server Error on the web server, rendering all files under the download path inaccessible.

Improper access control in debugging pages exposes an unauthorized file upload vulnerability

Figure 2 - Improper access control in debugging pages exposes an unauthorized file upload vulnerability 

Multiple file uploads were tested by the intruder using patterns consistent with the OWASP WSTG-BUSL-08 and WSTG-BUSL-09 testing guides

Figure 3 - Multiple file uploads were tested by the intruder using patterns consistent with the OWASP WSTG-BUSL-08 and WSTG-BUSL-09 testing guides 

Some of the uploaded files had the presence of malicious commands (see Figure 4).

[Green box] Preview of various malicious commands attempted to be uploaded and executed on the web server via the insecure web upload page

Figure 4 - [Green box] Preview of various malicious commands attempted to be uploaded and executed on the web server via the insecure web upload page 

Had they remained undiscovered, these hidden backdoors could have enabled repeated or persistent access by threat actors. The MDR team worked closely with Company A to validate and permanently remove the malicious scripts, effectively eliminating the risk of re-exploitation.

Containment & Remediation by Athena MDR Experts

Since Company A’s top priority was restoring access to the download directory, the MDR team, after briefing the management on the incident and obtaining approval, promptly removed the malicious file. This action immediately restored access to the affected repository. 

Following the full remediation of the incident, the Sangfor Athena MDR team transitioned from incident response to strategic advisory—providing Company A with tailored recommendations to reduce risk exposure and enhance cyber resilience in alignment with industry best practices.

Sangfor Athena MDR Values

For security leaders like CIOs and CISOs seeking to reduce operational risk and improve detection and response maturity, Sangfor Athena MDR serves as a strategic partner. We ensure that each incident becomes an opportunity to strengthen overall security posture.

Based on the case study above, it is evident that Athena MDR plays a critical role in delivering:

1) Rapid Response and Resolution

Sangfor Athena MDR acted fast. Within a day, the team identified the root cause, removed the malicious file, and restored system functionality. This prevented a prolonged outage that could have disrupted company-wide business operations the following workday.

2) 24/7 Continuous Vigilance

By providing round-the-clock monitoring, detection, and response, Sangfor Athena MDR helped mitigate the incident during non-business hours, when the security internal team was unavailable.

3) Deep Technical Expertise

The team did more than just resolve the surface issue. They conducted a thorough analysis to understand the underlying cause and ensured that no additional threats were present in the environment.

4) Collaborative Risk Mitigation

Sangfor worked closely with Company A to investigate the root cause, clearly explain the nature of the threat, cleanse the affected systems, and provide actionable guidance to prevent recurrence and address any residual risks.

5) Reinforcing Digital Trust

Through a prompt, expert-driven response, Sangfor Athena MDR helped restore stakeholder confidence. Company A and its partners now have increased trust in the security of their operations, regardless of evolving cybersecurity threats or future intrusion attempts.

6) Enhanced Readiness and SOC Maturity

By implementing the MDR team’s recommendations, Company A improved its SOC maturity by gaining the experience to detect and respond to future threats more effectively and efficiently.

Learn More About Sangfor Athena MDR

For a deeper look at how Athena MDR can protect your business with real-time threat detection and expert-led response, visit the Athena MDR service webpage or contact us directly with your enquiries.

 

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