Refactor genhex into shelltool

For convenience, I've rewritten my old shellcode parser program in
Python.  It is moved to the shellcode templates dir and renamed to
shelltool.

As a new feature, shelltool will now check the result for NULL bytes and
newline bytes that may cause problems in an exploit.

Signed-off-by: Malfurious <m@lfurio.us>

1 files changed, 30 insertions, 0 deletions

diff --git a/templates/shellcode/shelltool.py b/templates/shellcode/shelltool.py
new file mode 100755
index 0000000..b95a8cd
--- /dev/null
+++ b/templates/shellcode/shelltool.py
@@ -0,0 +1,30 @@
+#!/usr/bin/env python
+
+# This script will convert shellcode disassembly into an escaped string literal
+# and warn about problematic bytes in the payload.
+#     objdump -d elf | ./shelltool.py
+
+import sys
+
+name = None
+bytecode = []
+badchars = [ 0x00, 0x0a ]
+
+for line in sys.stdin:
+    for tok in line.split():
+        if name is None:
+            name = tok
+        if len(tok) == 2:
+            try:
+                bytecode.append(int(tok, base=16))
+            except:
+                pass
+
+result = ''.join([ "\\x%02x"%(x) for x in bytecode ])
+result = f'{name}"{result}"'
+
+for x in badchars:
+    if x in bytecode:
+        result += f'    **0x{"%02x"%(x)} detected**'
+
+print(result)