Overview

Symbol Slasher renames dynamic symbols on already-linked binaries. This obfuscates the interactions with private libraries, or simply prevents future linking to those libraries.

Building

Install the following:

• libLIEF
• nlohmann/json

To install on Ubuntu:

sudo apt install liblief-dev nlohmann-json-dev

Then run:

meson symbol-slasher build
cd build && ninja

Example

This section assumes you have built the example libraries and executable in /example.

Example library liba.so contains a simple print function. Example library libb.so contains its own print function, plus a wrapper for liba.so's print function. The executable main calls all three print functions. Some snippets from nm -DC:

liba.so:
00000000000011a5 T a::print(int, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >)

libb.so:
                 U a::print(int, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >)
0000000000001252 T b::a::print(int, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >)
00000000000011d5 T b::print(int, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >)

main:
                 U a::print(int, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >)
                 U b::a::print(int, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >)
                 U b::print(int, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >)

To build the symbol hash table, run:

symbol-slasher insert liba.so libb.so

Note that main does not need to be inserted into the table, since only defined symbols are inserted into the table (since there will always be some undefined symbols that are resolved by libstdc++, for example).

To create hash the symbol names, run:

mkdir hashed
symbol-slasher hash liba.so hashed/liba.so
symbol-slasher hash libb.so hashed/libb.so
symbol-slasher hash main hashed/main

Some snippets from nm -DC on the hashed binaries:

liba.so
00000000000011a5 T symslash2

libb.so:
00000000000011d5 T symslash0
0000000000001252 T symslash1
                 U symslash2
                 
main:
                 U symslash0
                 U symslash1
                 U symslash2

Credits

Logo by Nick