Trustwave SpiderLabs Uncovers Critical Cybersecurity Vulnerabilities Exposing Manufacturers to Costly Attacks. Learn More

Trustwave SpiderLabs Uncovers Critical Cybersecurity Vulnerabilities Exposing Manufacturers to Costly Attacks. Learn More

Managed Detection & Response

Eradicate cyberthreats with world-class intel and expertise

Managed Security Services

Expand your team’s capabilities and strengthen your security posture

Consulting & Professional Services

Tap into our global team of tenured cybersecurity specialists

Penetration Testing

Subscription- or project-based testing, delivered by global experts

Database Security

Get ahead of database risk, protect data and exceed compliance requirements

Email Security & Management

Catch email threats others miss with layered security & maximum control

Co-Managed SOC (SIEM)

Eliminate alert fatigue, focus your SecOps team, stop threats fast, and reduce cyber risk

Microsoft Exchange Server Attacks
Stay protected against emerging threats
Rapidly Secure New Environments
Security for rapid response situations
Securing the Cloud
Safely navigate and stay protected
Securing the IoT Landscape
Test, monitor and secure network objects
Why Trustwave
The Trustwave Approach
Awards and Accolades
Trustwave SpiderLabs Team
Trustwave Fusion Platform
SpiderLabs Fusion Center
Security Operations Centers
Technology Alliance Partners
Key alliances who align and support our ecosystem of security offerings
Trustwave PartnerOne Program
Join forces with Trustwave to protect against the most advance cybersecurity threats
SpiderLabs Blog

Vulnerability Causing Deletion of All Users in CrushFTP Admin Area

During a recent penetration test, Trustwave SpiderLabs researchers discovered a weak input validation vulnerability in the CrushFTP application which caused the deletion of all users. CrushFTP is a secure high- speed file transfer server that runs on almost any OS. It handles a wide array of protocols, and security options. It gives the server administrator the ability to customize, monitor, and control every aspect of the server’s operations:

CrushFTP stores details of registered users within the filesystem in the users/MainUsers directory.

The contents of this directory are shown below, with the default users crushadmin, default, and TempAccount, each having their own directory.


Figure 1: MainUsers directory content

Admin users have privileges to create additional accounts on the web interface. While testing for weak input validation, researchers tried various special characters in the username and realized that quotes and periods were not being blocked. As a result, it became possible to create a user named ““.” When this particular user was selected to be deleted the “.” was parsed directly to the filesystem without sanitization and was taken to mean part of the path which resulted in all users being removed.

The below screenshot shows the user manager page on the web interface.


Figure 2: User manager page on the web interface


A new directory containing details for the user ““.” was created on the file system.



Figure 3: New directory details for user “”.”


The user ““.” was selected to be deleted.



Figure 4: Deleting user “”.”


The below log lines show commands sent to the server when the user ““.” was deleted.

SERVER|10/26/2022 01:50:39.523|SETTINGS:users/MainUsers/&quot delete

SERVER|10/26/2022 01:50:39.532|SETTINGS:users/MainUsers/. Delete

The “.” was parsed directly to the filesystem without sanitization and all folders under MainUsers were deleted.



Figure 5: All folders under MainUsers deleted


On the web interface, researchers saw that the user list was empty.


Figure 6: Empty user list


As a result, users were not able to login.



Figure 7: Failed login


Responsible Disclosure

As a part of Trustwave’s Responsible Disclosure policy, we reached out to the vendor to ensure that a patch was released prior to public disclosure. CrushFTP was responsive and easy to work with throughout this process. The vendor fixed this issue in version 10.3.0_44:


Post-authentication vulnerabilities are often overlooked. However, when the post-authentication vulnerability exposes an administrator to attack, these issues deserve a closer look due to the risk associated with a successful attack. Given the right circumstances, a successful exploit can produce disastrous results.  


TWSL2023-002: Input validation Vulnerability in CRUSHFTP

Trustwave SpiderLabs Security Advisory TWSL2023-002

Latest SpiderLabs Blogs

Trustwave SpiderLabs Report: LockBit 3.0 Ransomware Vs. the Manufacturing Sector

As the manufacturing sector continues its digital transformation, Operational Technology (OT), Industrial Control Systems (ICS), and Supervisory Control and Data Acquisition (SCADA) are becoming...

Read More

Overview of the Cyberwarfare used in Israel – Hamas War

On October 7, 2023, the Palestinian organization Hamas launched the biggest attack on Israel in years, resulting in numerous casualties and hostages taken. Israel responded with a large-scale ground...

Read More

The 2023 Retail Services Sector Threat Landscape: A Trustwave Threat Intelligence Briefing

The annual holiday shopping season is poised for a surge in spending, a fact well-known to retailers, consumers, and cybercriminals alike. The latter group, however, is poised to exploit any...

Read More