External risk intelligence

Skipper File Upload Arbitrary Code Execution

CVE advisorySeverity: CRITICAL (CVSS 9.8)

CVE-2022-27262

Skipper is a body parser and file upload middleware for the Sails.js framework, which is commonly used to build internet-facing web applications and APIs. Because file upload functionality is a standard feature exposed to users in these web applications, the vulnerable component is likely to be reachable from the internet in common deployment patterns.

Unrestricted File Upload

Sailsjs Skipper

0.9.1

Halo Surface Signal: 4 out of 5 — likely to be public-facing.

External exposure likelihood

Horizon Alert

Summary of the vulnerability and why it matters

An arbitrary file upload vulnerability exists in a component used for processing file uploads in web applications. If exploited, this could allow an attacker to execute malicious code on affected systems, posing a significant risk to system integrity and confidentiality. The main concern is confirming relevance and exposure, as the vulnerability is reachable via the network.

Upload feature allows code execution.
It impacts system integrity and data confidentiality.
Confirm if this file upload tool is in use.

Attack Path

How an attacker could exploit the issue

An attacker can exploit this vulnerability by uploading a specially crafted file through the file upload module of Skipper. This is possible because the module does not properly validate uploaded files, allowing for the upload of malicious code. Successful exploitation could lead to arbitrary code execution on the server.

No authentication or special privileges needed.
Uploading a crafted file triggers the vulnerability.
Arbitrary code execution on the server.

Live Threat

Current exploitation, exposure, and threat context

This vulnerability could allow an attacker to upload and execute arbitrary code on a server running the Skipper file upload module. This could occur when the system is processing file uploads, potentially leading to unauthorized access and control over the affected system.

Arbitrary code execution on server.
Via crafted file upload.
System compromise and data loss.

Operational Fix

Recommended remediation, mitigation, and detection steps

The Skipper file upload module's arbitrary file upload vulnerability requires immediate attention from teams responsible for the application infrastructure and the Sails.js framework. The first practical step is to identify all instances of Skipper, confirm their accessibility, assess their business criticality, and then assign an owner for remediation planning.

Application owners should own the issue.
Verify deployment reachability and criticality.
Plan remediation based on risk assessment.

Supplementary metadata

CVSS vector

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Halo Threat Intelligence helps prioritize remediation with Halo Surface Signal and H/A/L/O context. Start exposure validation with a free external attack surface trial.

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Frequently asked questions

What is Skipper in the context of CVE-2022-27262?

Skipper is a middleware component designed for the Sails.js framework. It acts as a body parser specifically to handle and process file uploads within web applications. Developers integrate it into their Node.js environments to simplify the task of receiving, managing, and storing files submitted by users through web forms or API endpoints.

How does CVE-2022-27262 enable code execution?

This vulnerability falls under the Unrestricted Upload of File with Dangerous Type weakness class (CWE-434). It occurs because the software fails to properly inspect or restrict the types of files being uploaded. By submitting a crafted file designed to act as a script, an attacker can trick the server into treating the file as executable code, which the system then runs.

Do I need special access to trigger CVE-2022-27262?

No. The vulnerability does not require the attacker to have an account, special privileges, or prior authentication. Simply accessing the file upload functionality exposed by the application is sufficient. Note that the vulnerability is specifically triggered by the upload of the malicious file itself; legitimate, non-malicious file uploads do not inherently activate the code execution path.

Is my system at risk if it uses Skipper?

Halo Surface Signal indicates that because Skipper is typically used in internet-facing web applications to handle user uploads, it is often reachable from the public internet. If your application uses this component and is accessible online, it may be exposed. You should determine if your public-facing web services rely on this specific middleware to process incoming files.

What should I do if I run this technology?

Start by conducting an inventory to locate all instances of Skipper within your infrastructure. Once identified, evaluate the business criticality and network exposure of the applications using it. Assign clear ownership for these systems so that teams can track the installation, assess potential impacts on your data, and coordinate a path toward patching or removing the vulnerable component.

References

Written by Nicholas Merritt

Nicholas Merritt is VP of Security Solutions at Halo Security. With more than 25 years across application security, vulnerability prioritization, and offensive security, he helps teams translate threat data into practical exposure validation and remediation focus. He authors Halo Threat Intelligence CVE advisories using Halo Surface Signal and H/A/L/O context to prioritize internet-facing risk.