The main vulnerability (CVE-2017-13091) resides in the IEEE P1735 standard's use of AES-CBC mode.
Since the standard makes no recommendation for any specific padding scheme, the developers often choose the wrong scheme, making it possible for attackers to use a well-known classic padding-oracle attack (POA) technique to decrypt the system-on-chip blueprints without knowledge of the key.
Savitech provides USB audio drivers for a number of specialized audio products. Some versions of the Savitech driver package silently install a root CA certificate into the Windows trusted root certificate store.
Mitre assigned this exposure the identifier CVE-2017-9758, but was initially tracked by HITCON ZeroDay project as ZD-2017-00386.
有兩把 CA public key 被塞進去。雖然目前還沒有徵兆 private key 有外洩,但還是建議儘快移除:
There is currently no evidence that the Savitech private key is compromised. However, users are encouraged to remove the certificate out of caution. The two known certificates are:
SaviAudio root certificate #1
Validity: Thursday, May 31, 2012 - Tuesday, December 30, 2036
Serial number: 579885da6f791eb24de819bb2c0eeff0
Thumbprint: cb34ebad73791c1399cb62bda51c91072ac5b050
SaviAudio root certificate #2
Validity: Thursday, December 31, 2015 - Tuesday, December 30, 2036
Serial number: 972ed9bce72451bb4bd78bfc0d8b343c
Thumbprint: 23e50cd42214d6252d65052c2a1a591173daace5
另外 Savitech 也放出了新版的 driver,不包含 Root CA:
Savitech has released a new driver package to address the issue. Savitech drivers version 2.8.0.3 or later do not install the root CA certificate. Users still must remove any previously installed certificate manually.
看了一下說明,看起來是當時為了支援 Windows XP 而做的,但微軟已經不提供驅動程式的數位簽章了,所以就只好這樣搞...