From a2cd870eb98e410bd87e5b81e17c8a4e52c40f53 Mon Sep 17 00:00:00 2001
From: Martin Bickel <martin.bickel@continental-corporation.com>
Date: Mon, 20 Feb 2017 18:53:56 +0100
Subject: [PATCH] Added tool for anonymizing ELF files
---
.gitignore | 6 ++
configure.ac | 1 +
examples/Makefile.am | 2 +-
examples/Makefile.in | 2 +-
examples/anonymizer/Makefile.am | 3 +
examples/anonymizer/anonymizer.cpp | 145 +++++++++++++++++++++++++++++
6 files changed, 157 insertions(+), 2 deletions(-)
create mode 100644 examples/anonymizer/Makefile.am
create mode 100644 examples/anonymizer/anonymizer.cpp
diff --git a/.gitignore b/.gitignore
index 01e0b5c..d826675 100644
--- a/.gitignore
+++ b/.gitignore
@@ -11,6 +11,12 @@ ELFIOTest/Debug
ELFIOTest/ELFIOTest.vcxproj.user
examples/ELFDump/Debug
+examples/anonymizer/anonymizer
+examples/elfdump/elfdump
+examples/tutorial/tutorial
+examples/write_obj/write_obj
+examples/writer/writer
+
# generated elf files
elf_examples/*_copy
diff --git a/configure.ac b/configure.ac
index 64ead13..2d94110 100644
--- a/configure.ac
+++ b/configure.ac
@@ -7,6 +7,7 @@ AC_CONFIG_FILES([
examples/elfdump/Makefile
examples/tutorial/Makefile
examples/writer/Makefile
+ examples/anonymizer/Makefile
examples/write_obj/Makefile
])
AC_OUTPUT
diff --git a/examples/Makefile.am b/examples/Makefile.am
index 2dbce66..737e029 100644
--- a/examples/Makefile.am
+++ b/examples/Makefile.am
@@ -1 +1 @@
-SUBDIRS = elfdump tutorial writer write_obj
+SUBDIRS = elfdump tutorial writer write_obj anonymizer
diff --git a/examples/Makefile.in b/examples/Makefile.in
index 3595770..237a9e1 100644
--- a/examples/Makefile.in
+++ b/examples/Makefile.in
@@ -261,7 +261,7 @@ target_alias = @target_alias@
top_build_prefix = @top_build_prefix@
top_builddir = @top_builddir@
top_srcdir = @top_srcdir@
-SUBDIRS = elfdump tutorial writer write_obj
+SUBDIRS = elfdump tutorial writer write_obj Anonymizer
all: all-recursive
.SUFFIXES:
diff --git a/examples/anonymizer/Makefile.am b/examples/anonymizer/Makefile.am
new file mode 100644
index 0000000..214f9c4
--- /dev/null
+++ b/examples/anonymizer/Makefile.am
@@ -0,0 +1,3 @@
+AM_CPPFLAGS = -I$(top_srcdir)
+bin_PROGRAMS = anonymizer
+anonymizer_SOURCES = anonymizer.cpp
diff --git a/examples/anonymizer/anonymizer.cpp b/examples/anonymizer/anonymizer.cpp
new file mode 100644
index 0000000..a76bfd2
--- /dev/null
+++ b/examples/anonymizer/anonymizer.cpp
@@ -0,0 +1,145 @@
+/*
+anonymizer.cpp - Overwrites all data from an ELF file with random data.
+
+Copyright (C) 2017 by Martin Bickel
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in
+all copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+THE SOFTWARE.
+*/
+
+#ifdef _MSC_VER
+ #define _SCL_SECURE_NO_WARNINGS
+ #define ELFIO_NO_INTTYPES
+#endif
+
+#include <string>
+#include <iostream>
+#include <elfio/elfio_dump.hpp>
+#include <fstream>
+#include <random>
+
+using namespace ELFIO;
+
+
+bool preserve_name( const std::string& name ) {
+ static std::vector<std::string> names_to_preserve = { ".shstrtab",
+ ".rodata",
+ ".bss",
+ ".data",
+ ".text",
+ ".text_vle" };
+
+ for ( auto s = names_to_preserve.begin(); s != names_to_preserve.end(); ++s )
+ if ( *s == name)
+ return true;
+ return false;
+}
+
+std::default_random_engine generator(0xe1f);
+std::uniform_int_distribution<int> distribution(0,255);
+
+void randomize_data( const std::string& filename, long offset, long size ) {
+ std::ofstream file (filename, std::ios::in|std::ios::out|std::ios::binary);
+ if ( !file )
+ throw "error opening file" + filename;
+ file.seekp(offset);
+ for ( long i = 0; i < size; ++i ) {
+ const char value = distribution(generator);
+ file.write(&value, 1 );
+ }
+}
+
+void overwrite_data( const std::string& filename, long offset, const std::string& data ) {
+ std::ofstream file (filename, std::ios::in|std::ios::out|std::ios::binary);
+ if ( !file )
+ throw "error opening file" + filename;
+ file.seekp(offset);
+ file.write(data.c_str(), data.length()+1 );
+}
+
+
+
+std::string generate( int length ) {
+
+ static int counters[6] = { 0, 0, 10, 100, 1000, 10000 };
+
+ int counter = counters[length > 5 ? 5 : length ]++;
+
+ auto s = std::to_string(counter);
+ if ( s.length() > length ) {
+ throw "String length error at " + std::to_string( counter ) + "; expecting " + std::to_string( length ) + " bytes ";
+ }
+
+ while (s.length() < length)
+ s = "s" + s;
+ return s;
+}
+
+
+void processStringTable( const section* s, const std::string& filename ) {
+ std::cout << "Info: processing string table section" << std::endl;
+ int counter = 0;
+ int index = 1;
+ while ( index < s->get_size() ) {
+ auto len = strlen( s->get_data()+index );
+ if ( len && !preserve_name( s->get_data()+index ))
+ overwrite_data( filename, s->get_offset() + index, generate( len ));
+ index += len + 1;
+ counter++;
+ }
+ std::cout << counter << " strings found " << std::endl;
+}
+
+int main( int argc, char** argv )
+{
+ try {
+ if ( argc != 2 ) {
+ std::cout << "Usage: anonymizer <file_name>\n";
+ return 1;
+ }
+
+ std::string filename = argv[1];
+
+ elfio reader;
+
+ if ( !reader.load( filename ) ) {
+ std::cerr << "File " << filename << " is not found or it is not an ELF file\n";
+ return 1;
+ }
+
+ for ( auto sect = reader.sections.begin(); sect != reader.sections.end(); ++sect ) {
+ section* s = *sect;
+ if ( s->get_type() == SHT_STRTAB ) {
+ processStringTable(s, filename);
+ } else if ( s->get_type() == SHT_SYMTAB ) {
+ std::cout << "Skipping symbol table." << std::endl;
+ } else if ( s->get_type() == SHT_PROGBITS ) {
+ if ( s->get_size() > 0 ) {
+ randomize_data(filename, s->get_offset(), s->get_size());
+ std::cout << "Sanitized " << s->get_size() << " Bytes in section" << std::endl;
+ }
+ }
+ }
+ return 0;
+ } catch ( const std::string& s ) {
+ std::cerr << s << std::endl;
+ } catch ( const char* s ) {
+ std::cerr << s << std::endl;
+ }
+ return 1;
+}
--
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