1 // Copyright 2021 Code Intelligence GmbH 2 // 3 // Licensed under the Apache License, Version 2.0 (the "License"); 4 // you may not use this file except in compliance with the License. 5 // You may obtain a copy of the License at 6 // 7 // http://www.apache.org/licenses/LICENSE-2.0 8 // 9 // Unless required by applicable law or agreed to in writing, software 10 // distributed under the License is distributed on an "AS IS" BASIS, 11 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 12 // See the License for the specific language governing permissions and 13 // limitations under the License. 14 15 package com.example; 16 17 import com.code_intelligence.jazzer.api.FuzzedDataProvider; 18 import com.code_intelligence.jazzer.api.FuzzerSecurityIssueHigh; 19 import com.code_intelligence.jazzer.api.FuzzerSecurityIssueMedium; 20 import com.google.json.JsonSanitizer; 21 22 public class JsonSanitizerDenylistFuzzer { fuzzerTestOneInput(FuzzedDataProvider data)23 public static void fuzzerTestOneInput(FuzzedDataProvider data) { 24 String input = data.consumeRemainingAsString(); 25 String validJson; 26 try { 27 validJson = JsonSanitizer.sanitize(input, 10); 28 } catch (Exception e) { 29 return; 30 } 31 32 // Check for forbidden substrings. As these would enable Cross-Site Scripting, treat every 33 // finding as a high severity vulnerability. 34 assert !validJson.contains("</script") 35 : new FuzzerSecurityIssueHigh("Output contains </script"); 36 assert !validJson.contains("]]>") : new FuzzerSecurityIssueHigh("Output contains ]]>"); 37 38 // Check for more forbidden substrings. As these would not directly enable Cross-Site Scripting 39 // in general, but may impact script execution on the embedding page, treat each finding as a 40 // medium severity vulnerability. 41 assert !validJson.contains("<script") 42 : new FuzzerSecurityIssueMedium("Output contains <script"); 43 assert !validJson.contains("<!--") : new FuzzerSecurityIssueMedium("Output contains <!--"); 44 } 45 } 46