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// Copyright 2021 Code Intelligence GmbH
//
// 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.code_intelligence.jazzer.sanitizers
import com.code_intelligence.jazzer.api.HookType
import com.code_intelligence.jazzer.api.Jazzer
import com.code_intelligence.jazzer.api.MethodHook
import com.code_intelligence.jazzer.api.MethodHooks
import java.lang.invoke.MethodHandle
/**
* Detects injectable inputs to an expression language interpreter which may lead to remote code execution.
*/
@Suppress("unused_parameter", "unused")
object ExpressionLanguageInjection {
/**
* Try to call the default constructor of the honeypot class.
*/
private const val EXPRESSION_LANGUAGE_ATTACK =
"\${\"\".getClass().forName(\"$HONEYPOT_CLASS_NAME\").newInstance()}"
@MethodHooks(
MethodHook(
type = HookType.BEFORE,
targetClassName = "javax.el.ExpressionFactory",
targetMethod = "createValueExpression",
),
MethodHook(
type = HookType.BEFORE,
targetClassName = "javax.el.ExpressionFactory",
targetMethod = "createMethodExpression",
),
MethodHook(
type = HookType.BEFORE,
targetClassName = "jakarta.el.ExpressionFactory",
targetMethod = "createValueExpression",
),
MethodHook(
type = HookType.BEFORE,
targetClassName = "jakarta.el.ExpressionFactory",
targetMethod = "createMethodExpression",
),
)
@JvmStatic
fun hookElExpressionFactory(
method: MethodHandle?,
thisObject: Any?,
arguments: Array<Any>,
hookId: Int
) {
val expression = arguments[1] as? String ?: return
Jazzer.guideTowardsContainment(expression, EXPRESSION_LANGUAGE_ATTACK, hookId)
}
// With default configurations the argument to
// ConstraintValidatorContext.buildConstraintViolationWithTemplate() will be evaluated by an
// Expression Language interpreter which allows arbitrary code execution if the attacker has
// control of the method argument.
//
// References: CVE-2018-16621
// https://securitylab.github.com/research/bean-validation-RCE/
@MethodHook(
type = HookType.BEFORE,
targetClassName = "javax.validation.ConstraintValidatorContext",
targetMethod = "buildConstraintViolationWithTemplate"
)
@JvmStatic
fun hookBuildConstraintViolationWithTemplate(
method: MethodHandle?,
thisObject: Any?,
arguments: Array<Any>,
hookId: Int
) {
val message = arguments[0] as String
Jazzer.guideTowardsContainment(message, EXPRESSION_LANGUAGE_ATTACK, hookId)
}
}
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