def emul_symb(ir_arch, ircfg, mdis, states_todo, states_done):
while states_todo:
addr, symbols, conds = states_todo.pop()
print('*' * 40, "addr", addr, '*' * 40)
if (addr, symbols, conds) in states_done:
print('Known state, skipping', addr)
continue
states_done.add((addr, symbols, conds))
symbexec = SymbolicExecutionEngine(ir_arch)
symbexec.symbols = symbols.copy()
if ir_arch.pc in symbexec.symbols:
del symbexec.symbols[ir_arch.pc]
irblock = get_block(ir_arch, ircfg, mdis, addr)
print('Run block:')
print(irblock)
addr = symbexec.eval_updt_irblock(irblock)
print('Final state:')
symbexec.dump(mems=False)
assert addr is not None
if isinstance(addr, ExprCond):
# Create 2 states, each including complementary conditions
cond_group_a = {addr.cond: ExprInt(0, addr.cond.size)}
cond_group_b = {addr.cond: ExprInt(1, addr.cond.size)}
addr_a = expr_simp(
symbexec.eval_expr(addr.replace_expr(cond_group_a), {}))
addr_b = expr_simp(
symbexec.eval_expr(addr.replace_expr(cond_group_b), {}))
if not (addr_a.is_int() or addr_a.is_loc() and addr_b.is_int()
or addr_b.is_loc()):
print(str(addr_a), str(addr_b))
raise ValueError("Unsupported condition")
if isinstance(addr_a, ExprInt):
addr_a = int(addr_a.arg)
if isinstance(addr_b, ExprInt):
addr_b = int(addr_b.arg)
states_todo.add(
(addr_a, symbexec.symbols.copy(),
tuple(list(conds) + list(viewitems(cond_group_a)))))
states_todo.add(
(addr_b, symbexec.symbols.copy(),
tuple(list(conds) + list(viewitems(cond_group_b)))))
elif addr == ret_addr:
print('Return address reached')
continue
elif addr.is_int():
addr = int(addr.arg)
states_todo.add((addr, symbexec.symbols.copy(), tuple(conds)))
elif addr.is_loc():
states_todo.add((addr, symbexec.symbols.copy(), tuple(conds)))
else:
raise ValueError("Unsupported destination")
def intra_block_flow_symb(ir_arch, _, flow_graph, irblock, in_nodes,
out_nodes):
symbols_init = ir_arch.arch.regs.regs_init.copy()
sb = SymbolicExecutionEngine(ir_arch, symbols_init)
sb.eval_updt_irblock(irblock)
print('*' * 40)
print(irblock)
out = sb.modified(mems=False)
current_nodes = {}
# Gen mem arg to mem node links
for dst, src in out:
src = sb.eval_expr(dst)
for n in [dst, src]:
all_mems = set()
all_mems.update(get_expr_mem(n))
for n in all_mems:
node_n_w = get_node_name(irblock.loc_key, 0, n)
if not n == src:
continue
o_r = n.ptr.get_r(mem_read=False, cst_read=True)
for i, n_r in enumerate(o_r):
if n_r in current_nodes:
node_n_r = current_nodes[n_r]
else:
node_n_r = get_node_name(irblock.loc_key, i, n_r)
if not n_r in in_nodes:
in_nodes[n_r] = node_n_r
flow_graph.add_uniq_edge(node_n_r, node_n_w)
# Gen data flow links
for dst in out:
src = sb.eval_expr(dst)
nodes_r = src.get_r(mem_read=False, cst_read=True)
nodes_w = set([dst])
for n_r in nodes_r:
if n_r in current_nodes:
node_n_r = current_nodes[n_r]
else:
node_n_r = get_node_name(irblock.loc_key, 0, n_r)
if not n_r in in_nodes:
in_nodes[n_r] = node_n_r
flow_graph.add_node(node_n_r)
for n_w in nodes_w:
node_n_w = get_node_name(irblock.loc_key, 1, n_w)
out_nodes[n_w] = node_n_w
flow_graph.add_node(node_n_w)
flow_graph.add_uniq_edge(node_n_r, node_n_w)
def exec_instruction(mn_str, init_values, results, index=0, offset=0):
"""Symbolically execute an instruction and check the expected results."""
# Assemble and disassemble the instruction
instr = mn_mep.fromstring(mn_str, "b")
instr.mode = "b"
mn_bin = mn_mep.asm(instr)[index]
try:
instr = mn_mep.dis(mn_bin, "b")
except Disasm_Exception:
assert (False) # miasm don't know what to do
# Specify the instruction offset and compute the destination label
instr.offset = offset
loc_db = LocationDB()
if instr.dstflow():
instr.dstflow2label(loc_db)
# Get the IR
im = Lifter_MEPb(loc_db)
iir, eiir = im.get_ir(instr)
# Filter out IRDst
iir = [
ir for ir in iir
if not (isinstance(ir, ExprAssign) and isinstance(ir.dst, ExprId)
and ir.dst.name == "IRDst")
]
# Prepare symbolic execution
sb = SymbolicExecutionEngine(LifterModelCallMepb(loc_db), regs_init)
# Assign int values before symbolic evaluation
for expr_id, expr_value in init_values:
sb.symbols[expr_id] = expr_value
# Execute the IR
ab = AssignBlock(iir)
sb.eval_updt_assignblk(ab)
# Check if expected expr_id were modified
matched_results = 0
for expr_id, expr_value in results:
result = sb.eval_expr(expr_id)
if isinstance(result, ExprLoc):
addr = loc_db.get_location_offset(result.loc_key)
if expr_value.arg == addr:
matched_results += 1
continue
elif result == expr_value:
matched_results += 1
continue
# Ensure that all expected results were verified
if len(results) is not matched_results:
print("Expected:", results)
print("Modified:", [r for r in sb.modified(mems=False)])
assert (False)
def exec_instruction(mn_str, init_values, results, index=0, offset=0):
"""Symbolically execute an instruction and check the expected results."""
# Assemble and disassemble the instruction
instr = mn_mep.fromstring(mn_str, "b")
instr.mode = "b"
mn_bin = mn_mep.asm(instr)[index]
try:
instr = mn_mep.dis(mn_bin, "b")
except Disasm_Exception:
assert(False) # miasm don't know what to do
# Specify the instruction offset and compute the destination label
instr.offset = offset
loc_db = LocationDB()
if instr.dstflow():
instr.dstflow2label(loc_db)
# Get the IR
im = ir_mepb(loc_db)
iir, eiir = im.get_ir(instr)
# Filter out IRDst
iir = [ir for ir in iir if not (isinstance(ir, ExprAssign) and
isinstance(ir.dst, ExprId) and
ir.dst.name == "IRDst")]
# Prepare symbolic execution
sb = SymbolicExecutionEngine(ir_a_mepb(loc_db), regs_init)
# Assign int values before symbolic evaluation
for expr_id, expr_value in init_values:
sb.symbols[expr_id] = expr_value
# Execute the IR
ab = AssignBlock(iir)
sb.eval_updt_assignblk(ab)
# Check if expected expr_id were modified
matched_results = 0
for expr_id, expr_value in results:
result = sb.eval_expr(expr_id)
if isinstance(result, ExprLoc):
addr = loc_db.get_location_offset(result.loc_key)
if expr_value.arg == addr:
matched_results += 1
continue
elif result == expr_value:
matched_results += 1
continue
# Ensure that all expected results were verified
if len(results) is not matched_results:
print("Expected:", results)
print("Modified:", [r for r in sb.modified(mems=False)])
assert(False)
def emul(self, lifter, ctx=None, step=False):
# Init
ctx_init = {}
if ctx is not None:
ctx_init.update(ctx)
solver = z3.Solver()
symb_exec = SymbolicExecutionEngine(lifter, ctx_init)
history = self.history[::-1]
history_size = len(history)
translator = Translator.to_language("z3")
size = self._ircfg.IRDst.size
for hist_nb, loc_key in enumerate(history, 1):
if hist_nb == history_size and loc_key == self.initial_state.loc_key:
line_nb = self.initial_state.line_nb
else:
line_nb = None
irb = self.irblock_slice(self._ircfg.blocks[loc_key], line_nb)
# Emul the block and get back destination
dst = symb_exec.eval_updt_irblock(irb, step=step)
# Add constraint
if hist_nb < history_size:
next_loc_key = history[hist_nb]
expected = symb_exec.eval_expr(ExprLoc(next_loc_key, size))
solver.add(
self._gen_path_constraints(translator, dst, expected))
# Save the solver
self._solver = solver
# Return only inputs values (others could be wrongs)
return {
element: symb_exec.eval_expr(element)
for element in self.inputs
}
def emul_symb(ir_arch, ircfg, mdis, states_todo, states_done):
while states_todo:
addr, symbols, conds = states_todo.pop()
print('*' * 40, "addr", addr, '*' * 40)
if (addr, symbols, conds) in states_done:
print('Known state, skipping', addr)
continue
states_done.add((addr, symbols, conds))
symbexec = SymbolicExecutionEngine(ir_arch)
symbexec.symbols = symbols.copy()
if ir_arch.pc in symbexec.symbols:
del symbexec.symbols[ir_arch.pc]
irblock = get_block(ir_arch, ircfg, mdis, addr)
print('Run block:')
print(irblock)
addr = symbexec.eval_updt_irblock(irblock)
print('Final state:')
symbexec.dump(mems=False)
assert addr is not None
if isinstance(addr, ExprCond):
# Create 2 states, each including complementary conditions
cond_group_a = {addr.cond: ExprInt(0, addr.cond.size)}
cond_group_b = {addr.cond: ExprInt(1, addr.cond.size)}
addr_a = expr_simp(symbexec.eval_expr(addr.replace_expr(cond_group_a), {}))
addr_b = expr_simp(symbexec.eval_expr(addr.replace_expr(cond_group_b), {}))
if not (addr_a.is_int() or addr_a.is_loc() and
addr_b.is_int() or addr_b.is_loc()):
print(str(addr_a), str(addr_b))
raise ValueError("Unsupported condition")
if isinstance(addr_a, ExprInt):
addr_a = int(addr_a.arg)
if isinstance(addr_b, ExprInt):
addr_b = int(addr_b.arg)
states_todo.add((addr_a, symbexec.symbols.copy(), tuple(list(conds) + list(viewitems(cond_group_a)))))
states_todo.add((addr_b, symbexec.symbols.copy(), tuple(list(conds) + list(viewitems(cond_group_b)))))
elif addr == ret_addr:
print('Return address reached')
continue
elif addr.is_int():
addr = int(addr.arg)
states_todo.add((addr, symbexec.symbols.copy(), tuple(conds)))
elif addr.is_loc():
states_todo.add((addr, symbexec.symbols.copy(), tuple(conds)))
else:
raise ValueError("Unsupported destination")
def _normalize_ircfg(self, conn):
# unalias stack miasm.re/blog/2017/02/03/data_flow_analysis_depgraph.html , but involve base pointer too
# TODO remove manual *BP propagation in normalize_ircfg and use standrad Miasm propagation when it is fixed
# remove composes from bigger to smaller, they are not important for us
bp = {}
prev_offset = None
for irb_loc_key in self.ircfg.walk_breadth_first_forward(LocKey(0)):
irs = []
if irb_loc_key not in self.ircfg.blocks:
continue
irb = self.ircfg.blocks[irb_loc_key]
if irb.dst.is_cond() and irb.dst.cond.is_op() and irb.dst.cond.op == 'CC_EQ':
# TODO propagate cmp ..., arb_int too
# propagate known zeroes to process test eax, eax; jnz ...; lea edi, [eax+4]
symb_exec = SymbolicExecutionEngine(self.ir_arch)
dst = symb_exec.eval_updt_irblock(irb)
if dst.is_cond() and dst.cond.is_id() and not is_bad_expr(dst.cond) and \
symb_exec.eval_expr(dst.cond) == dst.cond:
# add explicit mov ID, 0 to given irb
target_loc = dst.src2
if target_loc.is_int():
target_loc = self.asmcfg.loc_db.get_offset_location(int(target_loc))
elif target_loc.is_loc():
target_loc = target_loc.loc_key
else:
continue
if len(self.ircfg.predecessors(target_loc)) > 1:
continue
target_irb = self.ircfg.blocks[target_loc]
asign_blk = AssignBlock([ExprAssign(dst.cond, ExprInt(0, dst.cond.size))])
assignblks = tuple([asign_blk, *target_irb.assignblks])
new_irb = IRBlock(target_loc, assignblks)
self.ircfg.blocks[target_loc] = new_irb
fix_dct = {}
for assignblk in irb:
offset = prev_offset
if assignblk.instr and assignblk.instr.offset:
offset = assignblk.instr.offset
prev_offset = offset
spd = conn.modules.idc.get_spd(offset)
if spd is not None:
stk_high = ExprInt(spd, self.ir_arch.sp.size)
fix_dct = {self.ir_arch.sp: self.mn.regs.regs_init[self.ir_arch.sp] + stk_high}
fix_dct.update(bp)
else:
logger.warning("Couldn't acquire stack depth at 0x%x" % (offset or 0x0BADF00D))
new_assignblk = {}
for dst, src in assignblk.items():
if src.is_compose():
slc_arg = None
arg = None
for tmp_arg in src.args:
if not tmp_arg.is_slice():
arg = tmp_arg
else:
# we're interested only in bigger to smaller
slc_arg = tmp_arg
if slc_arg and arg and len(arg.get_r()) == 1:
top_to_bottom_visitor = ExprVisitorCallbackTopToBottom(
lambda x: self._resize_top_expr(x, src.size))
src = top_to_bottom_visitor.visit(arg)
if dst == src:
# special compiler anomalies such as lea esp, [esp+0]
continue
if src == self.ir_arch.sp:
src = expr_simp(src.replace_expr(fix_dct))
if bp and src not in bp.values() and irb_loc_key != LocKey(0):
raise RuntimeError("Ambiguous base pointer")
bp.update({dst: src})
fix_dct.update(bp)
else:
src = expr_simp(src.replace_expr(fix_dct))
if dst != self.ir_arch.sp and dst not in bp.keys():
dst = dst.replace_expr(fix_dct)
dst, src = expr_simp(dst), expr_simp(src)
new_assignblk[dst] = src
irs.append(AssignBlock(new_assignblk, instr=assignblk.instr))
self.ircfg.blocks[irb.loc_key] = IRBlock(irb.loc_key, irs)
ircfg = lifter.new_ircfg()
first_block = list(asmcfg.blocks)[0]
lifter.add_asmblock_to_ircfg(first_block, ircfg)
# --- Symbolic execution --- #
from miasm.ir.symbexec import SymbolicExecutionEngine
from miasm.expression.expression import *
symb = SymbolicExecutionEngine(lifter, machine.mn.regs.regs_init)
# irDst contains the offset of next IR basic block to execute
irDst = symb.run_at(ircfg, entry_addr, step=False)
print("IR Dest = ", irDst)
# Provide symbolic context to irDst
expr_flag = ExprId("flag", 32)
result = symb.eval_expr(
expr_simp(
irDst.replace_expr(
{
expr_simp(
ExprMem(machine.mn.regs.EBP_init - ExprInt(0x4, 32), 32)):
expr_flag,
})))
print("IR Dest Semantics = ", result)
# Dump the final state of symbolic execution
# symb.dump()