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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.FuzzerSecurityIssueCritical
import com.code_intelligence.jazzer.api.HookType
import com.code_intelligence.jazzer.api.Jazzer
import com.code_intelligence.jazzer.api.MethodHook
import java.lang.invoke.MethodHandle
/**
* Detects unsafe execution of OS commands using [ProcessBuilder].
* Executing OS commands based on attacker-controlled data could lead to arbitrary could execution.
*
* All public methods providing the command to execute end up in [java.lang.ProcessImpl.start],
* so calls to this method are hooked.
* Only the first entry of the given command array is analyzed. It states the executable and must
* not include attacker provided data.
*/
@Suppress("unused_parameter", "unused")
object OsCommandInjection {
// Short and probably non-existing command name
private const val COMMAND = "jazze"
@MethodHook(
type = HookType.BEFORE,
targetClassName = "java.lang.ProcessImpl",
targetMethod = "start",
additionalClassesToHook = ["java.lang.ProcessBuilder"]
)
@JvmStatic
fun processImplStartHook(method: MethodHandle?, alwaysNull: Any?, args: Array<Any?>, hookId: Int) {
// Calling ProcessBuilder already checks if command array is empty
@Suppress("UNCHECKED_CAST")
(args[0] as? Array<String>)?.first().let { cmd ->
if (cmd == COMMAND) {
Jazzer.reportFindingFromHook(
FuzzerSecurityIssueCritical(
"""OS Command Injection
Executing OS commands with attacker-controlled data can lead to remote code execution."""
)
)
} else {
Jazzer.guideTowardsEquality(cmd, COMMAND, hookId)
}
}
}
}
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