CWE-111 对不安全JNI的直接使用

Direct Use of Unsafe JNI

结构: Simple

Abstraction: Base

状态: Draft

被利用可能性: unkown

基本描述

When a Java application uses the Java Native Interface (JNI) to call code written in another programming language, it can expose the application to weaknesses in that code, even if those weaknesses cannot occur in Java.

扩展描述

Many safety features that programmers may take for granted simply do not apply for native code, so you must carefully review all such code for potential problems. The languages used to implement native code may be more susceptible to buffer overflows and other attacks. Native code is unprotected by the security features enforced by the runtime environment, such as strong typing and array bounds checking.

相关缺陷

  • cwe_Nature: ChildOf cwe_CWE_ID: 695 cwe_View_ID: 1000 cwe_Ordinal: Primary

  • cwe_Nature: ChildOf cwe_CWE_ID: 20 cwe_View_ID: 700 cwe_Ordinal: Primary

  • cwe_Nature: ChildOf cwe_CWE_ID: 20 cwe_View_ID: 699 cwe_Ordinal: Primary

适用平台

Language: {'cwe_Name': 'Java', 'cwe_Prevalence': 'Undetermined'}

常见的影响

范围 影响 注释
Access Control Bypass Protection Mechanism

可能的缓解方案

Implementation

策略:

Implement error handling around the JNI call.

Implementation

策略: Refactoring

Do not use JNI calls if you don't trust the native library.

Implementation

策略: Refactoring

Be reluctant to use JNI calls. A Java API equivalent may exist.

示例代码

例

The following code defines a class named Echo. The class declares one native method (defined below), which uses C to echo commands entered on the console back to the user. The following C code defines the native method implemented in the Echo class:

bad Java

class Echo {

public native void runEcho();
static {

System.loadLibrary("echo");
}
public static void main(String[] args) {

new Echo().runEcho();
}
}

bad C

#include <jni.h>
#include "Echo.h"//the java class above compiled with javah
#include <stdio.h>

JNIEXPORT void JNICALL
Java_Echo_runEcho(JNIEnv *env, jobject obj)
{
char buf[64];
gets(buf);
printf(buf);
}

Because the example is implemented in Java, it may appear that it is immune to memory issues like buffer overflow vulnerabilities. Although Java does do a good job of making memory operations safe, this protection does not extend to vulnerabilities occurring in source code written in other languages that are accessed using the Java Native Interface. Despite the memory protections offered in Java, the C code in this example is vulnerable to a buffer overflow because it makes use of gets(), which does not check the length of its input.

The Sun Java(TM) Tutorial provides the following description of JNI [See Reference]: The JNI framework lets your native method utilize Java objects in the same way that Java code uses these objects. A native method can create Java objects, including arrays and strings, and then inspect and use these objects to perform its tasks. A native method can also inspect and use objects created by Java application code. A native method can even update Java objects that it created or that were passed to it, and these updated objects are available to the Java application. Thus, both the native language side and the Java side of an application can create, update, and access Java objects and then share these objects between them.

The vulnerability in the example above could easily be detected through a source code audit of the native method implementation. This may not be practical or possible depending on the availability of the C source code and the way the project is built, but in many cases it may suffice. However, the ability to share objects between Java and native methods expands the potential risk to much more insidious cases where improper data handling in Java may lead to unexpected vulnerabilities in native code or unsafe operations in native code corrupt data structures in Java. Vulnerabilities in native code accessed through a Java application are typically exploited in the same manner as they are in applications written in the native language. The only challenge to such an attack is for the attacker to identify that the Java application uses native code to perform certain operations. This can be accomplished in a variety of ways, including identifying specific behaviors that are often implemented with native code or by exploiting a system information exposure in the Java application that reveals its use of JNI [See Reference].

分类映射

映射的分类名 ImNode ID Fit Mapped Node Name
7 Pernicious Kingdoms Unsafe JNI
The CERT Oracle Secure Coding Standard for Java (2011) SEC08-J Define wrappers around native methods
SEI CERT Oracle Coding Standard for Java JNI01-J Safely invoke standard APIs that perform tasks using the immediate caller's class loader instance (loadLibrary)
SEI CERT Oracle Coding Standard for Java JNI00-J Imprecise Define wrappers around native methods
Software Fault Patterns SFP3 Use of an improper API

引用