scrap growth one nop at a time, store disassembly

Dockerfile

@@ -2,5 +2,5 @@ FROM ubuntu:bionic
 ENV DEBIAN_FRONTEND=noninteractive
 
 RUN apt-get update && apt-get install -y \
-  python3-sqlalchemy \
-  yasm
+  python3-capstone \
+  python3-sqlalchemy

sins/__init__.py

@@ -1,4 +1,4 @@
 #!/usr/bin/env python3
 from .run import sins
-from .mutation import generation, flip, seed_shell
+from .mutation import generation, mutate
 from .orm import db_config, ScrapNode

sins/disassemble.py

@@ -0,0 +1,13 @@
+#! /usr/bin/env python3
+from capstone import Cs, CS_ARCH_X86, CS_MODE_64
+import json
+
+capstone = Cs(CS_ARCH_X86, CS_MODE_64)
+
+def disasm(shellcode: bytes)->str:
+    opcodes = list()
+
+    for opcode in capstone.disasm(shellcode, 0):
+        opcodes.append([opcode.mnemonic, opcode.op_str])
+
+    return opcodes

sins/mutation.py

@@ -4,14 +4,6 @@ from random import randint
 import ctypes
 import mmap
 
-template_shell = b''.join([
-    b'\x55',              # push   rbp
-    b'\x48\x89\xe5',      # mov    rbp,rsp
-    b'\x48\x89\x7d\xf8',  # mov    QWORD [rbp-0x8],rdi
-    b'\x48\x8b\x45\xf8',  # mov    rax,QWORD [rbp-0x8]
-    b'\x5d',              # pop    rbp
-    b'\xc3'])             # ret
-
 seed_shell = b''.join([
     b'\x55',
     b'\x48\x89\xe5',
@@ -22,8 +14,19 @@ seed_shell = b''.join([
     b'\x5d',
     b'\xc3'])
 
+# use template to declutter output, todo
+seed_shell = b''.join([
+    b'\x55',              # push   rbp
+    b'\x48\x89\xe5',      # mov    rbp,rsp
+    b'\x90' * 8,          # nop
+    b'\x48\x89\x7d\xf8',  # mov    QWORD [rbp-0x8],rdi
+    b'\x90' * 8,          # nop
+    b'\x48\x8b\x45\xf8',  # mov    rax,QWORD [rbp-0x8]
+    b'\x5d',              # pop    rbp
+    b'\xc3'])             # ret
 
-def flip(shellcode: bytes):
+
+def mutate(shellcode: bytes):
     shellcode = bytearray(shellcode)
     offset = randint(0, len(shellcode) - 1)
     flip = randint(0, 255)
@@ -47,3 +50,17 @@ def generation(queue: Queue, shellcode: bytes):
     result = function(shellcode_len)
 
     queue.put(result)
+
+
+def growth(*, shellcode: bytes, length: int) -> bytes:
+    shellcode = bytearray(shellcode)
+
+    # slow growth and stop shrinking
+    if length > len(shellcode):
+        growth = 1
+    else:
+        growth = 0
+
+    shellcode = shellcode + (b'\x90' * growth)
+
+    return bytes(shellcode)

sins/orm.py

@@ -6,11 +6,11 @@ from sqlalchemy import LargeBinary, Column, ForeignKey, Integer, String, DateTim
 from sqlalchemy.ext.declarative import declarative_base
 from sqlalchemy.orm import Session, relationship, backref
 from sqlalchemy.orm.collections import attribute_mapped_collection
-import logging
+import json
+
+from .disassemble import disasm
 
-logger = logging.getLogger('sins')
 now = '{0:%Y%m%dT%H%M%S}'.format(datetime.utcnow())
-
 Base = declarative_base()
 
 
@@ -29,7 +29,7 @@ class ScrapNode(Base):
     mtime = Column(DateTime, onupdate=datetime.utcnow)
     parent_id = Column(Integer, ForeignKey(id))
     checksum = Column(String)
-    stdout = Column(String)
+    disasm = Column(String)
     image = Column(LargeBinary)
 
     children = relationship(
@@ -43,16 +43,18 @@ class ScrapNode(Base):
         self.image = child
         self.length = len(child)
         self.sha1sum
+        self.disasm = disasm(child)
 
     def __repr__(self):
         values = {
             'checksum': self.checksum,
             'length': self.length,
+            'disasm': self.disasm,
             'parent_id': self.parent_id,
             'id': self.id,
         }
 
-        return str(values)
+        return json.dumps(values, indent=1)
 
     @property
     def sha1sum(self):
@@ -64,3 +66,12 @@ class ScrapNode(Base):
         self.checksum = checksum.hexdigest()
 
         return self.checksum
+
+
+def disasm(shellcode: bytes) -> str:
+    opcodes = list()
+
+    for opcode in capstone.disasm(shellcode, 0):
+        opcodes += f'{opcode.mnemonic}    {opcode.op_str}\n'
+
+    return opcodes

sins/run.py

@@ -8,7 +8,7 @@ from sqlalchemy import exists, desc
 from tempfile import TemporaryDirectory
 import logging
 
-from .mutation import generation, flip, seed_shell
+from .mutation import generation, mutate, seed_shell, growth
 from .orm import db_config, ScrapNode
 
 
@@ -48,18 +48,6 @@ def sins():
 
     logger.info(now)
 
-    seed_data = seed_shell
-
-    if args.seed:
-        seed = Path(args.seed)
-
-        with seed.open('rb') as seed_file:
-            seed_data = seed_file.read()
-
-    seed = ScrapNode(child=seed_data)
-
-    logger.debug(f'seed:\n{seed}')
-
     if args.output:
         db_path = Path(f'{args.output}/sins.sqlite')
     else:
@@ -68,38 +56,48 @@ def sins():
 
     session = db_config(db_path)
     logger.info(f'db_path: {db_path}')
+    recent = session.query(ScrapNode).order_by(desc('ctime')).first()
 
     if args.seed:
+        seed_path = Path(args.seed)
+
+        with seed_path.open('rb') as seed_file:
+            seed_data = seed_file.read()
+
+        seed = ScrapNode(child=seed_data)
+
         exists = session.query(ScrapNode).filter(
             ScrapNode.checksum == seed.checksum)
 
         if exists:
             seed = exists[0]
-
         else:
             session.add(seed)
             session.commit()
+        logger.debug(f'args.seed:\n{seed}')
+    elif recent:
+        seed = recent
+        logger.debug(f'recent:\n{seed}')
     else:
-        recent = session.query(ScrapNode).order_by(desc('ctime')).first()
-
-        if recent:
-            logger.debug(f'recent:\n{recent}')
-            seed = recent
+        seed = ScrapNode(child=seed_shell)
+        session.add(seed)
+        session.commit()
+        logger.debug(f'seed_shell:\n{seed}')
 
     parent = seed
-
     queue = Queue()
 
     while True:
         lineage = 0
-        scrap = flip(parent.image)
 
         while lineage < args.lineage:
+            scrap = mutate(parent.image)
             logger.debug(f'lineage: {lineage}')
             result = None
 
             proc = Process(target=generation, args=(queue, scrap))
             proc.start()
+
             try:
                 result = queue.get(timeout=1)
             except Empty:
@@ -110,10 +108,11 @@ def sins():
                 lineage += 1
                 continue
 
+            scrap = growth(shellcode=scrap, length=result)
+
             parent = ScrapNode(child=scrap, parent_id=parent.id)
-            parent.length = result
             session.add(parent)
             session.commit()
+
             logger.info(f'scrap:\n{parent}')
             lineage = 0
-            scrap = flip(parent.image)