Add sanitization to log messages to reduce chance of tokens ending up in server logs

server/logging/Logger.ts

@@ -1,6 +1,6 @@
 import { IncomingMessage } from "http";
 import chalk from "chalk";
-import { isEmpty } from "lodash";
+import { isEmpty, isArray, isObject, isString } from "lodash";
 import winston from "winston";
 import env from "@server/env";
 import Metrics from "@server/logging/Metrics";
@@ -27,7 +27,7 @@ type Extra = Record<string, any>;
 class Logger {
   output: winston.Logger;
 
-  constructor() {
+  public constructor() {
     this.output = winston.createLogger({
       level: env.LOG_LEVEL,
     });
@@ -54,8 +54,8 @@ class Logger {
    * @param category A log message category that will be prepended
    * @param extra Arbitrary data to be logged that will appear in prod logs
    */
-  info(label: LogCategory, message: string, extra?: Extra) {
-    this.output.info(message, { ...extra, label });
+  public info(label: LogCategory, message: string, extra?: Extra) {
+    this.output.info(message, { ...this.sanitize(extra), label });
   }
 
   /**
@@ -64,8 +64,8 @@ class Logger {
    * @param category A log message category that will be prepended
    * @param extra Arbitrary data to be logged that will appear in prod logs
    */
-  debug(label: LogCategory, message: string, extra?: Extra) {
-    this.output.debug(message, { ...extra, label });
+  public debug(label: LogCategory, message: string, extra?: Extra) {
+    this.output.debug(message, { ...this.sanitize(extra), label });
   }
 
   /**
@@ -74,7 +74,7 @@ class Logger {
    * @param message A warning message
    * @param extra Arbitrary data to be logged that will appear in prod logs
    */
-  warn(message: string, extra?: Extra) {
+  public warn(message: string, extra?: Extra) {
     Metrics.increment("logger.warning");
 
     if (env.SENTRY_DSN) {
@@ -90,7 +90,7 @@ class Logger {
     }
 
     if (isProduction) {
-      this.output.warn(message, extra);
+      this.output.warn(message, this.sanitize(extra));
     } else if (extra) {
       console.warn(message, extra);
     } else {
@@ -106,7 +106,7 @@ class Logger {
    * @param extra Arbitrary data to be logged that will appear in prod logs
    * @param request An optional request object to attach to the error
    */
-  error(
+  public error(
     message: string,
     error: Error,
     extra?: Extra,
@@ -122,7 +122,7 @@ class Logger {
         scope.setLevel("error");
 
         for (const key in extra) {
-          scope.setExtra(key, extra[key]);
+          scope.setExtra(key, this.sanitize(extra[key]));
         }
 
         if (request) {
@@ -147,6 +147,56 @@ class Logger {
       });
     }
   }
+
+  /**
+   * Sanitize data attached to logs and errors to remove sensitive information.
+   *
+   * @param input The data to sanitize
+   * @returns The sanitized data
+   */
+  private sanitize<T>(input: T): T {
+    // Short circuit if we're not in production to enable easier debugging
+    if (!isProduction) {
+      return input;
+    }
+
+    const sensitiveFields = [
+      "accessToken",
+      "refreshToken",
+      "token",
+      "password",
+      "content",
+    ];
+
+    if (isString(input)) {
+      if (sensitiveFields.some((field) => input.includes(field))) {
+        return "[Filtered]" as T;
+      }
+    }
+
+    if (isArray(input)) {
+      return input.map(this.sanitize) as T;
+    }
+
+    if (isObject(input)) {
+      const output = { ...input };
+
+      for (const key of Object.keys(output)) {
+        if (isObject(output[key])) {
+          output[key] = this.sanitize(output[key]);
+        } else if (isArray(output[key])) {
+          output[key] = output[key].map(this.sanitize);
+        } else if (sensitiveFields.includes(key)) {
+          output[key] = "[Filtered]";
+        } else {
+          output[key] = this.sanitize(output[key]);
+        }
+      }
+      return output;
+    }
+
+    return input;
+  }
 }
 
 export default new Logger();