1 // Copyright 2021 Google LLC 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 //////////////////////////////////////////////////////////////////////////////// 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 DenylistFuzzer { fuzzerTestOneInput(FuzzedDataProvider data)23 public static void fuzzerTestOneInput(FuzzedDataProvider data) { 24 String input = data.consumeRemainingAsString(); 25 String output; 26 try { 27 output = JsonSanitizer.sanitize(input, 10); 28 } catch (ArrayIndexOutOfBoundsException e) { 29 // ArrayIndexOutOfBoundsException is expected if nesting depth is 30 // exceeded. 31 return; 32 } 33 34 // Check for forbidden substrings. As these would enable Cross-Site 35 // Scripting, treat every finding as a high severity vulnerability. 36 assert !output.contains("</script") 37 : new FuzzerSecurityIssueHigh("Output contains </script"); 38 assert !output.contains("]]>") 39 : new FuzzerSecurityIssueHigh("Output contains ]]>"); 40 41 // Check for more forbidden substrings. As these would not directly enable 42 // Cross-Site Scripting in general, but may impact script execution on the 43 // embedding page, treat each finding as a medium severity vulnerability. 44 assert !output.contains("<script") 45 : new FuzzerSecurityIssueMedium("Output contains <script"); 46 assert !output.contains("<!--") 47 : new FuzzerSecurityIssueMedium("Output contains <!--"); 48 } 49 } 50