/**
* Find Security Bugs
* Copyright (c) Philippe Arteau, All rights reserved.
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 3.0 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library.
*/
package com.h3xstream.findsecbugs.cookie;
import com.h3xstream.findsecbugs.common.ByteCode;
import edu.umd.cs.findbugs.BugInstance;
import edu.umd.cs.findbugs.BugReporter;
import edu.umd.cs.findbugs.Detector;
import edu.umd.cs.findbugs.Priorities;
import edu.umd.cs.findbugs.ba.CFG;
import edu.umd.cs.findbugs.ba.CFGBuilderException;
import edu.umd.cs.findbugs.ba.ClassContext;
import edu.umd.cs.findbugs.ba.Location;
import org.apache.bcel.classfile.JavaClass;
import org.apache.bcel.classfile.Method;
import org.apache.bcel.generic.ALOAD;
import org.apache.bcel.generic.ASTORE;
import org.apache.bcel.generic.ConstantPoolGen;
import org.apache.bcel.generic.INVOKESPECIAL;
import org.apache.bcel.generic.INVOKEVIRTUAL;
import org.apache.bcel.generic.Instruction;
import java.util.Iterator;
import org.apache.bcel.generic.InstructionHandle;
public class CookieFlagsDetector implements Detector {
private static final String INSECURE_COOKIE_TYPE = "INSECURE_COOKIE";
private static final String HTTPONLY_COOKIE_TYPE = "HTTPONLY_COOKIE";
private BugReporter bugReporter;
private static final int TRUE_INT_VALUE = 1;
public CookieFlagsDetector(BugReporter bugReporter) {
this.bugReporter = bugReporter;
}
@Override
public void visitClassContext(ClassContext classContext) {
JavaClass javaClass = classContext.getJavaClass();
Method[] methodList = javaClass.getMethods();
for (Method m : methodList) {
try {
analyzeMethod(m,classContext);
} catch (CFGBuilderException e) {
}
}
}
private void analyzeMethod(Method m, ClassContext classContext) throws CFGBuilderException {
//System.out.println("==="+m.getName()+"===");
ConstantPoolGen cpg = classContext.getConstantPoolGen();
CFG cfg = classContext.getCFG(m);
for (Iterator<Location> i = cfg.locationIterator(); i.hasNext(); ) {
Location loc = i.next();
//ByteCode.printOpCode(loc.getHandle().getInstruction(), cpg);
Instruction inst = loc.getHandle().getInstruction();
if(inst instanceof INVOKESPECIAL) {
INVOKESPECIAL invoke = (INVOKESPECIAL) inst;
if ("javax.servlet.http.Cookie".equals(invoke.getClassName(cpg)) &&
"<init>".equals(invoke.getMethodName(cpg))) {
// The following call should push the cookie onto the stack
Instruction cookieStoreInstruction = loc.getHandle().getNext().getInstruction();
if (cookieStoreInstruction instanceof ASTORE) {
// We will use the position of the object on the stack to track the cookie
ASTORE storeInstruction = (ASTORE)cookieStoreInstruction;
Location setSecureLocation = getSetSecureLocation(cpg, loc, storeInstruction.getIndex());
if (setSecureLocation == null) {
JavaClass javaClass = classContext.getJavaClass();
bugReporter.reportBug(new BugInstance(this, INSECURE_COOKIE_TYPE, Priorities.NORMAL_PRIORITY) //
.addClass(javaClass)
.addMethod(javaClass, m)
.addSourceLine(classContext, m, loc));
}
Location setHttpOnlyLocation = getSetHttpOnlyLocation(cpg, loc, storeInstruction.getIndex());
if (setHttpOnlyLocation == null) {
JavaClass javaClass = classContext.getJavaClass();
bugReporter.reportBug(new BugInstance(this, HTTPONLY_COOKIE_TYPE, Priorities.NORMAL_PRIORITY) //
.addClass(javaClass)
.addMethod(javaClass, m)
.addSourceLine(classContext, m, loc));
}
}
}
}
}
}
/**
* This method is used to track calls made on a specific object. For instance, this could be used to track if "setHttpOnly(true)"
* was executed on a specific cookie object.
*
* This allows the detector to find interchanged calls like this
*
* Cookie cookie1 = new Cookie("f", "foo"); <- This cookie is unsafe
* Cookie cookie2 = new Cookie("b", "bar"); <- This cookie is safe
* cookie1.setHttpOnly(false);
* cookie2.setHttpOnly(true);
*
* @param cpg ConstantPoolGen
* @param startLocation The Location of the cookie initialization call.
* @param objectStackLocation The index of the cookie on the stack.
* @param invokeInstruction The instruction we want to detect.s
* @return The location of the invoke instruction provided for the cookie at a specific index on the stack.
*/
private Location getCookieInstructionLocation(ConstantPoolGen cpg, Location startLocation, int objectStackLocation, String invokeInstruction) {
Location location = startLocation;
InstructionHandle handle = location.getHandle();
int loadedStackValue = 0;
// Loop until we find the setSecure call for this cookie
while (handle.getNext() != null) {
handle = handle.getNext();
Instruction nextInst = handle.getInstruction();
// We check if the index of the cookie used for this invoke is the same as the one provided
if (nextInst instanceof ALOAD) {
ALOAD loadInst = (ALOAD)nextInst;
loadedStackValue = loadInst.getIndex();
}
if (nextInst instanceof INVOKEVIRTUAL
&& loadedStackValue == objectStackLocation) {
INVOKEVIRTUAL invoke = (INVOKEVIRTUAL) nextInst;
String methodNameWithSignature = invoke.getClassName(cpg) + "." + invoke.getMethodName(cpg);
if (methodNameWithSignature.equals(invokeInstruction)) {
Integer val = ByteCode.getConstantInt(handle.getPrev());
if (val != null && val == TRUE_INT_VALUE) {
return new Location(handle, location.getBasicBlock());
}
}
}
}
return null;
}
private Location getSetSecureLocation(ConstantPoolGen cpg, Location startLocation, int stackLocation) {
return getCookieInstructionLocation(cpg, startLocation, stackLocation, "javax.servlet.http.Cookie.setSecure");
}
private Location getSetHttpOnlyLocation(ConstantPoolGen cpg, Location startLocation, int stackLocation) {
return getCookieInstructionLocation(cpg, startLocation, stackLocation, "javax.servlet.http.Cookie.setHttpOnly");
}
@Override
public void report() {
}
}