threat-modeling.md

Threat Model Analysis for fyne-io/fyne

Threat: Threat 1: Buffer Overflow in Fyne's Rendering Engine

Description: An attacker crafts malicious input (e.g., a specially designed image, text string, or custom widget data) that, when processed by Fyne's rendering engine, causes a buffer overflow. This could overwrite adjacent memory, potentially leading to arbitrary code execution. The attacker might exploit a vulnerability in how Fyne handles image scaling, text layout, or custom widget rendering. Impact: Arbitrary code execution on the user's system, potentially leading to complete system compromise. Affected Fyne Component: fyne.io/fyne/v2/canvas (and related sub-packages like canvas/raster, canvas/text), potentially platform-specific rendering backends (OpenGL, etc.). Risk Severity: Critical *Mitigation Strategies: * Developer: * Fyne developers should conduct rigorous fuzz testing of the rendering engine with various inputs. * Implement robust bounds checking in all rendering-related code. * Use memory-safe languages or techniques (Go's built-in bounds checking helps, but vulnerabilities are still possible). * Regularly audit the rendering code for potential buffer overflow vulnerabilities. * Application Developer: * Keep Fyne updated to the latest version. * Validate and sanitize all user-provided data before passing it to Fyne widgets, especially images and text. * Avoid using overly complex or custom-drawn widgets unless absolutely necessary and thoroughly tested.

Threat: Threat 2: Cross-Context Scripting (XCS) in widget.Entry or widget.RichText (with widget.Webview)

Description: If an application displays user-provided text in a widget.Entry or widget.RichText without proper sanitization, and this text is later used within a widget.Webview, an attacker could inject malicious scripts. This leverages the interaction between Fyne widgets and a web context. Impact: The attacker could execute arbitrary JavaScript within the context of the widget.Webview, potentially accessing local files (if the webview is configured to allow it) or communicating with external servers. Affected Fyne Component: fyne.io/fyne/v2/widget.Entry, fyne.io/fyne/v2/widget.RichText, fyne.io/fyne/v2/widget.Webview (specifically when used together). Risk Severity: High *Mitigation Strategies: * Developer: * Always sanitize and escape user-provided text before displaying it in a widget.Entry or widget.RichText, especially if that text might be used in a widget.Webview later. * Use HTML escaping if the text might be used in a widget.Webview. * Configure the widget.Webview securely: * Disable JavaScript if it's not absolutely necessary. * Restrict access to local files using appropriate settings. * Consider using a Content Security Policy (CSP) within the webview. * Application Developer: * Avoid mixing contexts. If possible, don't use user input from Fyne widgets directly within a widget.Webview. If you must, perform thorough sanitization.

Threat: Threat 3: Information Disclosure via fyne.io/fyne/v2/storage (if Fyne's implementation is flawed)

Description: While application developers are responsible for encrypting sensitive data, a hypothetical vulnerability within Fyne's storage implementation itself could lead to information disclosure. For example, if Fyne incorrectly handles file permissions, uses a predictable storage location, or has a bug in its abstraction layer that bypasses platform-specific security mechanisms. This is distinct from the application developer misusing the API. Impact: Disclosure of sensitive information stored using Fyne's storage API, even if the application developer attempts to encrypt it (because the underlying Fyne implementation is flawed). Affected Fyne Component: fyne.io/fyne/v2/storage. Risk Severity: High *Mitigation Strategies: * Fyne Developer: * Thoroughly audit the storage implementation on all supported platforms to ensure it correctly uses platform-specific secure storage mechanisms (Keychain, Credential Manager, etc.). * Ensure that file permissions are set correctly to prevent unauthorized access. * Avoid using predictable or easily guessable storage locations. * Provide clear documentation on the security guarantees of the storage API and any limitations. * Application Developer: * Keep Fyne updated. * While you should encrypt data yourself, be aware that a Fyne bug could still expose it. Consider using platform-specific APIs directly for highly sensitive data if you have concerns about Fyne's storage implementation.

Threat: Threat 4: DLL Hijacking on Windows (Affecting Fyne's Dependencies)

Description: Fyne (or one of its dependencies) loads a DLL from an insecure location on Windows. An attacker places a malicious DLL with the same name in a directory that's searched before the legitimate DLL's location (e.g., the application's directory, the current working directory). When the application loads the DLL, it loads the malicious one instead. Impact: Arbitrary code execution with the privileges of the application. Affected Fyne Component: Any Fyne component that uses external DLLs (this is platform-specific and depends on Fyne's dependencies). Risk Severity: High *Mitigation Strategies: * Developer: * Ensure that all DLLs are loaded from trusted locations (e.g., the system directory, a signed application directory). * Use absolute paths when loading DLLs. * Use the SetDllDirectory function to restrict the DLL search path. * Digitally sign all DLLs. * Application Developer/User: * Install the application in a secure location (e.g., Program Files). * Avoid running the application from untrusted directories. * Keep the operating system and antivirus software up to date.