The travis_encrypt_binstar_token implementation in the conda-smithy package has been identified as vulnerable to an Oracle Padding Attack. This vulnerability results from the use of an outdated and insecure padding scheme during RSA encryption. A malicious actor with access to an oracle system can exploit this flaw by iteratively submitting modified ciphertexts and analyzing responses to infer the plaintext without possessing the private key.

Affected File:
https://github.com/conda-forge/conda-smithy/blob/[...]/conda_smithy/ci_register.py#L447

Affected Code:

def travis_encrypt_binstar_token(repo, string_to_encrypt):
   [...]
   import base64

   from Crypto.Cipher import PKCS1_v1_5
   from Crypto.PublicKey import RSA

   keyurl = f"https://api.travis-ci.com/repo/{repo}/key_pair/generated"
   r = requests.get(keyurl, headers=travis_headers())
   r.raise_for_status()
   public_key = r.json()["public_key"]
   key = RSA.importKey(public_key)
   cipher = PKCS1_v1_5.new(key)
   return base64.b64encode(cipher.encrypt(string_to_encrypt.encode())).decode(
       "utf-8"
   )

The use of RSA-OAEP (Optimal Asymmetric Encryption Padding) is recommended to mitigate padding oracle attacks.