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How to remediate – AspUpload Test11.asp Arbitrary File Upload

Contents

1. Introduction

The AspUpload Test11.asp Arbitrary File Upload vulnerability allows attackers to upload malicious files to a web server running an ASP script called AspUpload. This can lead to complete compromise of the affected system, allowing data theft, modification or denial of service. Systems commonly affected are those hosting websites using vulnerable versions of AspUpload scripts. A successful exploit could result in loss of confidentiality, integrity and availability.

2. Technical Explanation

The vulnerability exists because an example script distributed with AspUpload does not properly validate file uploads. This allows attackers to upload arbitrary files and store them anywhere on the affected drive. CVE-2001-0938 describes this issue. An attacker could, for instance, upload a malicious ASP script that executes commands on the server.

  • Root cause: Missing input validation when handling file uploads in the AspUpload example script.
  • Exploit mechanism: An attacker sends a crafted HTTP request containing a malicious file to the vulnerable script. The script saves the file to an arbitrary location on the server.
  • Scope: Web servers running ASP scripts with the vulnerable AspUpload component installed.

3. Detection and Assessment

To confirm vulnerability, check for the presence of the example script and its version. A thorough method involves attempting a test upload.

  • Quick checks: Check web server directories for files named ‘test11.asp’ or similar AspUpload scripts.
  • Scanning: Nessus plugin ID 3608 can detect this vulnerability, but results should be verified manually.
  • Logs and evidence: Web server logs may show requests to the vulnerable script with suspicious file names or extensions.
dir C:inetpubwwwroot /s /b test11.asp

4. Solution / Remediation Steps

The solution is currently unknown, but removing the AspUpload example scripts and updating to a patched version (if available) are recommended.

4.1 Preparation

  • Ensure you have access to restore the backup in case of issues. A roll back plan involves restoring from the pre-change backup.
  • Change windows may be required depending on service impact, and approval from system owners is recommended.

4.2 Implementation

  1. Step 1: Locate all instances of ‘test11.asp’ or similar AspUpload example scripts within the web server directories.
  2. Step 2: Delete the identified vulnerable script files.
  3. Step 3: If a patched version of AspUpload is available, download and install it following the vendor’s instructions.

4.3 Config or Code Example

Before

<%@ include file="test11.asp" %>

After

4.4 Security Practices Relevant to This Vulnerability

Practices that directly address this vulnerability type include least privilege and input validation.

  • Practice 1: Least privilege – limiting web server account permissions reduces the impact if an attacker uploads a malicious file.
  • Practice 2: Input validation – rigorously validating all user-supplied data, including file uploads, prevents attackers from submitting harmful content.

4.5 Automation (Optional)

# PowerShell example - use with caution!
# Get-ChildItem -Path C:inetpubwwwroot -Filter test11.asp -Recurse | Remove-Item -Force

5. Verification / Validation

Confirm the fix by checking for the absence of the vulnerable script and attempting a test upload. A simple service smoke test involves browsing the website to ensure functionality remains intact.

  • Post-fix check: Run `dir C:inetpubwwwroot /s /b test11.asp` – no results should be returned.
  • Re-test: Repeat the initial detection steps (directory search) to confirm the script is no longer present.
  • Smoke test: Verify that core website functionality, such as browsing pages and submitting forms, still works as expected.
  • Monitoring: Monitor web server logs for any attempts to access or upload files to the previously vulnerable directory.
dir C:inetpubwwwroot /s /b test11.asp

6. Preventive Measures and Monitoring

Update security baselines to include file upload restrictions, and add checks in CI/CD pipelines to prevent vulnerable code from being deployed.

  • Baselines: Update a web server security baseline or policy to disallow execution of scripts from the uploads directory.
  • Asset and patch process: Implement a regular patch review cycle for all web server components, including ASP scripts.

7. Risks, Side Effects, and Roll Back

Removing the script may break functionality if it is used by other parts of the website. The roll back steps involve restoring from the pre-change backup.

  • Risk or side effect 1: Removing a required script file could cause website errors.
  • Risk or side effect 2: Incorrectly configured web server permissions may prevent access to other files.
  • Roll back: Restore the web server from the pre-change backup.

8. References and Resources

Updated on October 26, 2025

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