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Threat Model Analysis for slackhq/slacktextviewcontroller

Threat: Input Manipulation via Custom Attachments

  • Description: An attacker could craft a malicious attachment (e.g., a specially formatted image or file) that exploits a vulnerability in the SLKTextViewController's attachment handling logic. This could lead to code execution, denial of service, or data corruption. The attacker might also try to inject malicious data through custom attachment previews. This is direct because it targets the specific attachment processing mechanisms within STVC.
  • Impact: Application crash, arbitrary code execution (in severe cases), data corruption, denial of service. Could compromise the entire application and potentially the device.
  • Affected Component: SLKTextViewController's attachment handling, including SLKAttachment objects, custom NSTextAttachment subclasses, and the textView:shouldInteractWithAttachment:inRange:interaction: delegate method. Custom attachment preview views are also at risk.
  • Risk Severity: Critical (if code execution is possible) / High (if denial of service or data corruption is possible).
  • Mitigation Strategies:
    • Thoroughly validate all attachment data before processing it. Check file types, sizes, and contents for anomalies, using robust validation routines, not just file extensions.
    • Use secure libraries for handling different attachment types (e.g., image processing, file parsing). Ensure these libraries are kept up-to-date.
    • Avoid executing code from attachments directly. If absolutely necessary, use extreme caution and strong sandboxing.
    • Implement sandboxing or other isolation techniques to limit the impact of a compromised attachment, preventing it from accessing other parts of the application or system.
    • Sanitize and validate data displayed in custom attachment previews. Assume preview data is potentially malicious.
    • Regularly update dependencies and libraries used for attachment handling, patching any known vulnerabilities.

Threat: Data Leakage via Autocomplete Suggestions

  • Description: An attacker could analyze network traffic or application memory to glean sensitive information displayed in custom autocomplete suggestions. If the autocomplete logic pulls data from an insecure source (e.g., a local cache that's not properly encrypted, or a backend API without proper authorization), the attacker could retrieve this data. The attacker might also try to manipulate the autocomplete data source to inject malicious suggestions. This is direct because it targets STVC's custom autocomplete features.
  • Impact: Exposure of sensitive user data (e.g., previously entered messages, contact information, API keys if improperly handled). Could lead to identity theft, financial loss, or unauthorized access to other systems.
  • Affected Component: SLKTextViewController's autocomplete functionality, specifically custom implementations of textView:completionForPrefix:range:. The SLKAutoCompletionView and any custom data sources used for autocomplete suggestions are also affected.
  • Risk Severity: High (if sensitive data is involved).
  • Mitigation Strategies:
    • Ensure autocomplete data sources are secure. Use encrypted storage for local caches and implement proper authentication/authorization for backend APIs.
    • Avoid storing sensitive data in autocomplete suggestions. If unavoidable, use strong encryption and consider short-lived caches.
    • Validate and sanitize data retrieved from autocomplete data sources before displaying it.
    • Limit the scope of data exposed in autocomplete suggestions (e.g., only show relevant snippets, not entire messages).
    • Implement rate limiting on autocomplete requests to prevent attackers from rapidly querying the data source.

Threat: Pasteboard Data Exposure

  • Description: An attacker with access to the device (especially a jailbroken device) could monitor the pasteboard for sensitive data copied into the SLKTextViewController. If the application doesn't clear the pasteboard after processing the input, the data remains accessible to other applications. This is direct because it involves STVC's interaction with the system pasteboard.
  • Impact: Exposure of sensitive data copied into the text view (e.g., passwords, API keys, confidential messages). Could lead to unauthorized access, data breaches, or other malicious activities.
  • Affected Component: The SLKTextView component and its interaction with the system pasteboard (UIPasteboard). The canPaste: method and any custom paste handling logic are relevant.
  • Risk Severity: High (if sensitive data is handled).
  • Mitigation Strategies:
    • Programmatically clear the pasteboard (UIPasteboard.general.string = "") after the input is processed (e.g., after the message is sent). This is the most crucial mitigation.
    • Consider disabling copy/paste functionality entirely for SLKTextView instances that handle highly sensitive data. Use textView.editable = NO or override canPerformAction:withSender: to prevent pasting. This is a strong, but potentially user-unfriendly, mitigation.
    • Educate users about the risks of pasting sensitive information.
    • Use the UIPasteboardDetectionPattern (iOS 14+) to detect and warn users about potentially sensitive content on the pasteboard.

Threat: Improper Handling of Text Attributes

  • Description: If custom text attributes (e.g., for styling, mentions, or custom links) are not handled correctly within the SLKTextView, an attacker might be able to inject malicious data or cause unexpected behavior. A poorly handled URL scheme, specifically within the context of STVC's text rendering, could lead to the execution of arbitrary code. This is direct because it targets how STVC processes and displays attributed strings.
    • Impact: Potential for code execution (if URL schemes are mishandled), application crashes, or unexpected UI behavior.
    • Affected Component: SLKTextView and its handling of NSAttributedString and custom NSTextAttachment subclasses. The textView:shouldInteractWithURL:inRange:interaction: delegate method is particularly relevant.
    • Risk Severity: High (if code execution is possible).
    • Mitigation Strategies:
      • Thoroughly validate all URLs and other custom attributes before processing them within the SLKTextView.
      • Use a whitelist of allowed URL schemes, strictly enforcing this list.
      • Avoid executing code based on user-provided attributes without proper sanitization and validation. Assume all attributes are potentially malicious.
      • Use the system-provided URL handling mechanisms whenever possible, and ensure they are used securely.