Source: psirt@esri.com
ArcGIS Server versions 11.5 and earlier on Windows and Linux do not sufficiently validate uploaded files, enabling a remote unauthenticated attacker to upload arbitrary files to the server’s designated upload directories. However, the server’s architecture enforces controls that restrict uploaded files to non‑executable storage locations and prevent modification or replacement of existing application components or system configurations. Uploaded files cannot be executed, leveraged to escalate privileges, or used to access sensitive data. Because the issue does not enable execution, service disruption, unauthorized access, or integrity compromise, its impact on confidentiality, integrity, and availability is low. Note that race conditions, secret values, or man‑in‑the‑middle conditions are required for exploitation.
ArcGIS Server versions 11.5 and earlier are vulnerable to arbitrary file upload, allowing attackers to place files on the server. While the vulnerability is limited by architectural constraints preventing code execution, it could be leveraged in conjunction with other vulnerabilities or race conditions to achieve a more significant impact. The primary risk is potential information gathering or a foothold for future attacks.
Step 1: Target Identification: The attacker identifies a vulnerable ArcGIS Server instance running a version 11.5 or earlier on either Windows or Linux.
Step 2: Upload Preparation: The attacker crafts a malicious file to upload. The nature of the file depends on the attacker's goals, but it could be a file designed to exploit a race condition or gather information.
Step 3: File Upload: The attacker uses a crafted request to upload the malicious file to the server's designated upload directory. The request bypasses the insufficient input validation.
Step 4: File Placement: The server, due to the lack of proper validation, accepts the file and stores it in the upload directory.
Step 5: Post-Upload Exploitation (if possible): The attacker attempts to leverage the uploaded file. This step is highly dependent on the server's configuration, other vulnerabilities, and the attacker's creativity. This could involve attempting to trigger a race condition, using the uploaded file to gather information, or attempting to exploit another vulnerability.
The vulnerability stems from insufficient input validation of uploaded files within ArcGIS Server. Specifically, the server fails to adequately sanitize or validate the uploaded files' content, allowing an attacker to upload arbitrary files to designated upload directories. The root cause is a missing or inadequate check on file content or file type, allowing the upload of files that should be rejected. The description mentions that the server's architecture prevents execution and modification of core components. However, the lack of validation opens the door for potential exploitation through race conditions or other vulnerabilities that might allow an attacker to leverage the uploaded files for malicious purposes, such as information gathering or denial-of-service.
No specific APT groups or malware families are directly linked to this vulnerability due to its limited impact. However, any threat actor targeting ArcGIS Server instances could potentially leverage this vulnerability as part of a broader attack chain. Not listed on CISA KEV.
Network traffic analysis: Examine HTTP POST requests to the server, specifically those targeting file upload endpoints. Look for unusual file extensions or content types.
File system monitoring: Monitor the designated upload directories for the creation of unexpected files or files with suspicious names or extensions.
Log analysis: Review server logs for file upload events, paying close attention to any errors or warnings related to file processing. Look for unusual file sizes or upload times.
Intrusion Detection/Prevention Systems (IDS/IPS): Configure rules to detect suspicious file uploads based on file type, content, or request patterns.
Upgrade to ArcGIS Server version 11.6 or later. This is the primary and most effective remediation.
Implement robust input validation: Ensure that all uploaded files are properly validated, including file type, content, and size. Use allowlisting instead of blocklisting.
Restrict upload directories: Limit the allowed file types and sizes that can be uploaded. Configure the server to only accept necessary file types.
Regularly scan the upload directories for suspicious files.
Implement file integrity monitoring to detect unauthorized file modifications.
Harden the server's configuration: Disable unnecessary services and features. Apply the principle of least privilege.
Monitor server logs and network traffic for suspicious activity.