- Reported
-
- Issued
-
- Package
-
bip322
(crates.io)
- Type
-
Vulnerability
- Categories
-
- Keywords
-
#bip322
#bitcoin
#signature-verification
- Aliases
-
- References
-
- CVSS Score
- 9.1
CRITICAL
- CVSS Details
-
- Attack Vector
- Network
- Attack Complexity
- Low
- Privileges Required
- None
- User Interaction
- None
- Scope
- Unchanged
- Confidentiality Impact
- High
- Integrity Impact
- High
- Availability Impact
- None
- CVSS Vector
- CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
- Patched
-
- Unaffected
-
- Affected Functions
- Version
bip322::verify_full-
bip322::verify_full_encoded-
bip322::verify_simple-
bip322::verify_simple_encoded-
Description
Affected versions of bip322 accepted a BIP-322 proof created with an
attacker-controlled private key as a valid signature for an unrelated victim
P2WPKH or P2SH-P2WPKH address, allowing complete authentication bypass in
applications using verify_simple, verify_simple_encoded, verify_full, or
verify_full_encoded as proof that a user controls a Bitcoin address.
In verify_full, the verifier obtained the public key from the
caller-controlled witness and passed it to verify_full_p2wpkh, where the
supposed public-key mismatch check read the key from the same witness and
compared it with itself:
let witness_pub_key = &witness.to_vec()[1];
if &pub_key.to_bytes() != witness_pub_key {
return Err(Error::PublicKeyMismatch);
}
Since pub_key was originally parsed from that exact witness element, this
comparison was tautological. The code verified that the signature was valid
for the public key embedded in the witness, but never verified that this
public key hashes to the claimed address, violating BIP-322's requirement
that the message_signature satisfy the message_challenge (the claimed
address's scriptPubKey).
As a result, an attacker could select any victim P2WPKH or P2SH-P2WPKH
address, construct the BIP-322 challenge for that address and message, sign
it with their own unrelated private key, and have the proof accepted. No
victim key or victim interaction was required. Application-level nonces do
not mitigate this, since the attacker can construct and sign the current
challenge message with their own key.
P2TR verification is not affected: the public key is derived from the
address's witness program rather than from the caller-controlled witness.
The flaw was corrected in commit
e8accbe
by deriving the expected scriptPubKey from the witness public key
(P2WPKH(HASH160(pubkey)), wrapped in P2SH for the nested case) and
requiring it to exactly equal the scriptPubKey of the claimed address before
signature verification, failing with Error::PublicKeyMismatch otherwise.
The fix is included in version
0.0.11. Affected versions 0.0.6
through 0.0.10 have been yanked from crates.io.
There is no known workaround that mitigates the vulnerability. Upgrading to
version 0.0.11 is the recommended course of action.
Advisory available under CC0-1.0
license.