CVSS 4.9 · Medium EPSS 0,35%
Kerentanan Observable Discrepancy pada wolfssl. Skor CVSS 3.1 4.9 (Medium) menurut NVD.
Generating the ECDSA nonce k samples a random number r and then truncates this randomness with a modular reduction mod n where n is the order of the elliptic curve. Meaning k = r mod n. The division used during the reduction estimates a factor q_e by dividing the upper two digits (a digit having e.g. a size of 8 byte) of r by the upper digit of n and then decrements q_e in a loop until it has the correct size. Observing the number of times q_e is decremented through a control-flow revealing side-channel reveals a bias in the most significant bits of k. Depending on the curve this is either a negligible bias or a significant bias large enough to reconstruct k with lattice reduction methods. For SECP160R1, e.g., we find a bias of 15 bits.
CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:N/A:N
· uraikan di kalkulator | Vendor | Produk | Versi terdampak |
|---|---|---|
| wolfssl | wolfssl | Semua versi sebelum 5.7.2 |