SB2016030101 - Information disclosure in OpenSSL
Published: March 1, 2016 Updated: November 8, 2022
Security Bulletin ID
SB2016030101
CSH Severity
Medium
Patch available
YES
Number of vulnerabilities
2
Exploitation vector
Remote access
Highest impact
Data manipulation
Breakdown by Severity
- Low
- Medium
- High
- Critical
Description
This security bulletin contains information about 2 vulnerabilities.
1) Information disclosure (CVE-ID: CVE-2016-0800)
CWE-ID: CWE-327 - Use of a Broken or Risky Cryptographic Algorithm
CVSSv4: CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N/E:A/U:Green
The vulnerability allows a remote attacker to decrypt sensitive information.
The vulnerability exists due to usage of weak SSLv2 protocol, which requires to send a ServerVerify message before establishing that a client possesses certain plaintext RSA data. A remote attacker can decrypt TLS ciphertext data by leveraging a Bleichenbacher RSA padding oracle.
The vulnerability is dubbed "DROWN" attack.
2) Information disclosure (CVE-ID: CVE-2016-0702)
CWE-ID: CWE-200 - Exposure of sensitive information to an unauthorized actor
CVSSv4: CVSS:4.0/AV:L/AC:L/AT:P/PR:L/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N/E:U/U:Clear
The vulnerability allows a local attacker to decrypt data passed via encrypted SSL connection.
The vulnerability exists in the MOD_EXP_CTIME_COPY_FROM_PREBUF() function in crypto/bn/bn_exp.c. The application does not properly consider cache-bank access times during modular exponentiation, which makes it easier for local users to discover RSA keys by running a crafted application on the same Intel Sandy Bridge CPU core as a victim and leveraging cache-bank conflicts.
The vulnerability was dubbed "CacheBleed".
Remediation
Install update from vendor's website.