| /* |
| * Copyright (C) 2014 The Android Open Source Project |
| * |
| * Licensed under the Apache License, Version 2.0 (the "License"); |
| * you may not use this file except in compliance with the License. |
| * You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an "AS IS" BASIS, |
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| * See the License for the specific language governing permissions and |
| * limitations under the License. |
| */ |
| |
| package com.android.tools.lint.checks; |
| |
| import com.android.annotations.NonNull; |
| import com.android.annotations.Nullable; |
| import com.android.tools.lint.client.api.JavaEvaluator; |
| import com.android.tools.lint.client.api.JavaParser; |
| import com.android.tools.lint.detector.api.Category; |
| import com.android.tools.lint.detector.api.ConstantEvaluator; |
| import com.android.tools.lint.detector.api.Detector; |
| import com.android.tools.lint.detector.api.Detector.JavaPsiScanner; |
| import com.android.tools.lint.detector.api.Implementation; |
| import com.android.tools.lint.detector.api.Issue; |
| import com.android.tools.lint.detector.api.JavaContext; |
| import com.android.tools.lint.detector.api.Scope; |
| import com.android.tools.lint.detector.api.Severity; |
| import com.intellij.psi.JavaElementVisitor; |
| import com.intellij.psi.PsiExpression; |
| import com.intellij.psi.PsiMethod; |
| import com.intellij.psi.PsiMethodCallExpression; |
| |
| import java.util.Collections; |
| import java.util.List; |
| |
| public class GetSignaturesDetector extends Detector implements JavaPsiScanner { |
| public static final Issue ISSUE = Issue.create( |
| "PackageManagerGetSignatures", //$NON-NLS-1$ |
| "Potential Multiple Certificate Exploit", |
| "Improper validation of app signatures could lead to issues where a malicious app " + |
| "submits itself to the Play Store with both its real certificate and a fake " + |
| "certificate and gains access to functionality or information it shouldn't " + |
| "have due to another application only checking for the fake certificate and " + |
| "ignoring the rest. Please make sure to validate all signatures returned " + |
| "by this method.", |
| Category.SECURITY, |
| 8, |
| Severity.INFORMATIONAL, |
| new Implementation( |
| GetSignaturesDetector.class, |
| Scope.JAVA_FILE_SCOPE)) |
| .addMoreInfo("https://bluebox.com/technical/android-fake-id-vulnerability/"); |
| |
| private static final String PACKAGE_MANAGER_CLASS = "android.content.pm.PackageManager"; //$NON-NLS-1$ |
| private static final String GET_PACKAGE_INFO = "getPackageInfo"; //$NON-NLS-1$ |
| private static final int GET_SIGNATURES_FLAG = 0x00000040; //$NON-NLS-1$ |
| |
| // ---- Implements JavaScanner ---- |
| |
| @Override |
| @Nullable |
| public List<String> getApplicableMethodNames() { |
| return Collections.singletonList(GET_PACKAGE_INFO); |
| } |
| |
| @Override |
| public void visitMethod(@NonNull JavaContext context, @Nullable JavaElementVisitor visitor, |
| @NonNull PsiMethodCallExpression node, @NonNull PsiMethod method) { |
| JavaEvaluator evaluator = context.getEvaluator(); |
| if (!evaluator.methodMatches(method, PACKAGE_MANAGER_CLASS, true, |
| JavaParser.TYPE_STRING, |
| JavaParser.TYPE_INT)) { |
| return; |
| } |
| |
| PsiExpression[] arguments = node.getArgumentList().getExpressions(); |
| if (arguments.length == 2) { |
| PsiExpression second = arguments[1]; |
| Object number = ConstantEvaluator.evaluate(context, second); |
| if (number instanceof Number) { |
| int flagValue = ((Number)number).intValue(); |
| maybeReportIssue(flagValue, context, node, second); |
| } |
| } |
| } |
| |
| private static void maybeReportIssue( |
| int flagValue, JavaContext context, PsiMethodCallExpression node, |
| PsiExpression last) { |
| if ((flagValue & GET_SIGNATURES_FLAG) != 0) { |
| context.report(ISSUE, node, context.getLocation(last), |
| "Reading app signatures from getPackageInfo: The app signatures " |
| + "could be exploited if not validated properly; " |
| + "see issue explanation for details."); |
| } |
| } |
| } |