JEP290机制详解：Java反序列化漏洞的防护新标准<\/h1>

0x00 背景介绍<\/h2>

JEP290是Oracle在2016年提出的Java增强提案，最初是为Java 9设计的新特性，但随后被向下移植到JDK 6、7、8版本中。该机制的主要目的是提供一套标准化的反序列化防护方案，有效缓解Java反序列化漏洞带来的安全风险。<\/p>

版本支持情况<\/strong>：<\/p>

JDK 8u121<\/li>
JDK 7u131<\/li>
JDK 6u141<\/li> <\/ul>
0x01 JEP290核心机制<\/h2>
JEP290主要实现了以下安全机制：<\/p>

类过滤机制<\/strong>：提供黑白名单方式限制可反序列化的类<\/li>
复杂度限制<\/strong>：控制反序列化的深度和复杂度<\/li>
RMI验证<\/strong>：为RMI远程调用对象提供类验证机制<\/li>
可配置过滤<\/strong>：支持通过properties文件定义过滤器<\/li> <\/ol>
ObjectInputFilter接口<\/h3>
JEP290的核心是ObjectInputFilter<\/code>接口，开发者可以通过ObjectInputStream.setInternalObjectInputFilter()<\/code>方法设置过滤器。在反序列化过程中，底层会根据过滤器规则进行判断，返回三种状态：<\/p>
Status.ACCEPT<\/code>：允许反序列化<\/li> Status.REJECT<\/code>：拒绝反序列化<\/li> Status.UNDECIDED<\/code>：未决定，由后续过滤器决定<\/li> <\/ul> 0x02 配置方式<\/h2> JEP290提供了两种配置过滤器的方式：<\/p> 系统属性配置<\/strong>：<\/p> System.<\/span>setProperty<\/span>(<\/span>"jdk.serialFilter"<\/span>,<\/span> "规则表达式"<\/span>);<\/span> <\/span><\/span><\/code><\/pre><\/li> 配置文件<\/strong>：修改conf\/security\/java.properties<\/code>文件<\/p> <\/li> <\/ol> 0x03 RMI过滤机制详解<\/h2> RMI(远程方法调用)是Java反序列化漏洞的高发区域。JEP290为RMI引入了专门的过滤机制：<\/p> 过滤流程<\/h3> 在导出远程对象前，先执行过滤器逻辑<\/li> 反序列化时检查每个类是否符合过滤规则<\/li> 对于不符合规则的类直接抛出异常<\/li> <\/ol> 核心过滤逻辑<\/h3> 在RegistryImpl.registryFilter<\/code>方法中，RMI对远程对象的检查条件如下：<\/p> return<\/span> String.<\/span>class<\/span> !=<\/span> var2 &&<\/span> <\/span><\/span> !<\/span>Number.<\/span>class<\/span>.<\/span>isAssignableFrom<\/span>(<\/span>var2)<\/span> &&<\/span> <\/span><\/span> !<\/span>Remote.<\/span>class<\/span>.<\/span>isAssignableFrom<\/span>(<\/span>var2)<\/span> &&<\/span> <\/span><\/span> !<\/span>Proxy.<\/span>class<\/span>.<\/span>isAssignableFrom<\/span>(<\/span>var2)<\/span> &&<\/span> <\/span><\/span> !<\/span>UnicastRef.<\/span>class<\/span>.<\/span>isAssignableFrom<\/span>(<\/span>var2)<\/span> &&<\/span> <\/span><\/span> !<\/span>RMIClientSocketFactory.<\/span>class<\/span>.<\/span>isAssignableFrom<\/span>(<\/span>var2)<\/span> &&<\/span> <\/span><\/span> !<\/span>RMIServerSocketFactory.<\/span>class<\/span>.<\/span>isAssignableFrom<\/span>(<\/span>var2)<\/span> &&<\/span> <\/span><\/span> !<\/span>ActivationID.<\/span>class<\/span>.<\/span>isAssignableFrom<\/span>(<\/span>var2)<\/span> &&<\/span> <\/span><\/span> !<\/span>UID.<\/span>class<\/span>.<\/span>isAssignableFrom<\/span>(<\/span>var2)<\/span> <\/span><\/span> ?<\/span> Status.<\/span>REJECTED<\/span> :<\/span> Status.<\/span>ALLOWED<\/span>;<\/span> <\/span><\/span><\/code><\/pre>这个规则明确禁止了AnnotationInvocationHandler<\/code>等常用于攻击的类。<\/p> 0x04 技术实现细节<\/h2> 反序列化检查流程<\/h3> ObjectInputStream.readObject()<\/code>开始反序列化<\/li> 调用readObject0()<\/code>方法<\/li> 进入readOrdinaryObject()<\/code> → readClassDesc()<\/code> → readProxyDesc()<\/code><\/li> 获取接口并逐个调用filterCheck<\/code>方法检查<\/li> 最后对对象本身进行检查<\/li> <\/ol> 过滤器检查方法<\/h3> private<\/span> Status filterCheck<\/span>(<\/span>Class<?><\/span> clazz,<\/span> int<\/span> arrayLength)<\/span> {<\/span> <\/span><\/span> if<\/span> (<\/span>serialFilter !=<\/span> null<\/span>)<\/span> {<\/span> <\/span><\/span> return<\/span> serialFilter.<\/span>checkInput<\/span>(<\/span>new<\/span> FilterValues(<\/span>clazz,<\/span> arrayLength,<\/span> ...));<\/span> <\/span><\/span> }<\/span> <\/span><\/span> return<\/span> Status.<\/span>UNDECIDED<\/span>;<\/span> <\/span><\/span>}<\/span> <\/span><\/span><\/code><\/pre>0x05 安全影响分析<\/h2> 防护效果<\/strong>：<\/p> 有效拦截了已知的恶意反序列化链<\/li> 提供了标准化的防护方案，减少了自定义过滤器的实现风险<\/li> <\/ul> <\/li> 局限性<\/strong>：<\/p> 黑名单机制仍可能遗漏某些库或新出现的gadgets<\/li> 开发者配置不当仍可能导致防护失效<\/li> 不覆盖所有Java序列化场景<\/li> <\/ul> <\/li> 绕过可能性<\/strong>：<\/p> 寻找不在黑名单中的新gadget链<\/li> 利用白名单中的类构造攻击链<\/li> 针对特定应用的定制化绕过<\/li> <\/ul> <\/li> <\/ol> 0x06 最佳实践建议<\/h2> 及时更新JDK<\/strong>：确保使用支持JEP290的JDK版本<\/li> 配置严格规则<\/strong>：尽可能使用白名单而非黑名单<\/li> 自定义过滤器<\/strong>：根据应用特点扩展过滤规则<\/li> 监控与审计<\/strong>：记录被拦截的序列化尝试<\/li> 深度防御<\/strong>：JEP290应作为安全策略的一部分，而非唯一防护措施<\/li> <\/ol> 0x07 总结<\/h2> JEP290机制的引入标志着Java官方对反序列化安全问题的高度重视，为开发者提供了标准化的防护方案。虽然不能完全消除反序列化漏洞的风险，但显著提高了攻击门槛，迫使攻击者寻找更复杂、更受限的攻击路径。开发者应当充分了解这一机制，合理配置并配合其他安全措施，构建纵深防御体系。<\/p>