[FG-VD-18-126] Buffer Overflow Vulnerability in Latest EOS's EOSIO.WASMSDK Repository II

ID H1:391099
Type hackerone
Reporter kushal89shah
Modified 2019-02-19T09:17:09


Hello Block.One / EOS Product Security Team,

Good Afternoon.

There exists a Memory Corruption vulnerability in the latest EOS WASMSDK Library. The PoC.wasm file is attached along with this report.

Reproduction Steps: -

1) Fetch latest EOS WASMSDK repsository from 2) Compile and Build WASMSDK using default compiler. OR 2) Compile and Build WASMSDK using afl-clang-fast and afl-clang-fast++ compilers from AFL fuzzer. 3) Run the attached PoC.wasm file with eosio-objdump using the "-s" flag.

Exact command to reproduce the Vulnerability is "eosio-objdump -s PoC.wasm" without the double quotes.

Below is the Buffer Overflow Crash GDB output of the eosio-objdump tool with the PoC.wasm file.

Starting program: /usr/local/bin/eosio-objdump -s PoC.wasm [Thread debugging using libthread_db enabled] Using host libthread_db library "/lib/x86_64-linux-gnu/".

Program received signal SIGSEGV, Segmentation fault. llvm::PrintSectionContents (Obj=<optimized out>) at /home/h4ck3r/Documents/eosio.wasmsdk/eosio_llvm/tools/llvm-objdump/llvm-objdump.cpp:1829 1829 outs() << hexdigit((Contents[addr + i] >> 4) & 0xF, true)

0 llvm::PrintSectionContents (Obj=<optimized out>) at /home/h4ck3r/Documents/eosio.wasmsdk/eosio_llvm/tools/llvm-objdump/llvm-objdump.cpp:1829

1 0x0000000000431cac in DumpObject (o=0xf0bee0, a=<optimized out>) at /home/h4ck3r/Documents/eosio.wasmsdk/eosio_llvm/tools/llvm-objdump/llvm-objdump.cpp:2127

2 0x0000000000420d37 in DumpInput (file=...) at /home/h4ck3r/Documents/eosio.wasmsdk/eosio_llvm/tools/llvm-objdump/llvm-objdump.cpp:2212

3 std::for_each<__gnu_cxx::__normal_iterator<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >, std::vector<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >, std::allocator<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > > > >, void ()(llvm::StringRef)> (__first=..., __last=..., __f=<optimized out>)

at /usr/bin/../lib/gcc/x86_64-linux-gnu/5.4.0/../../../../include/c++/5.4.0/bits/stl_algo.h:3767

4 llvm::for_each<llvm::cl::list<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >, bool, llvm::cl::parser<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > > >&, void (*)(llvm::StringRef)> (Range=..., P=<optimized out>) at /home/h4ck3r/Documents/eosio.wasmsdk/eosio_llvm/include/llvm/ADT/STLExtras.h:902

5 main (argc=<optimized out>, argv=<optimized out>) at /home/h4ck3r/Documents/eosio.wasmsdk/eosio_llvm/tools/llvm-objdump/llvm-objdump.cpp:2273

Also you can find the attached Valgrind output for this Vulnerability.

The Git log as seen below shows that this is the latest version available as of this report.

h4ck3r@h4ck3r-VirtualBox:~/Documents/eosio.wasmsdk$ git log -1 commit 34ea7717dc918b32a09d3cba953c879d2014db72 Merge: 4a8eb03 d220a0b Author: Bucky Kittinger <> Date: Wed Aug 1 19:15:39 2018 -0400

Merge pull request #29 from EOSIO/develop

Merge develop into master


Eagerly awaiting your response.

Thanking You,

Yours Sincerely, Kushal Arvind Shah. Senior Security Researcher | Fortinet's FortiGuard Labs.

NOTE: This Bug Report Submission does not provide the option to select the target i.e. EOSIO WASMSDK Repository/Source Code, due to which the researcher had to select EOS source code. Please update the Bug Submission Options for the same. Thankyou.


Memory Corruption and Potential Information Disclosure & Arbitrary Code Execution.