CVE-2016-2183
Description
A flaw was found in the way the DES/3DES cipher was used as part of the TLS/SSL protocol. A man-in-the-middle attacker could use this flaw to recover some plaintext data by capturing large amounts of encrypted traffic between TLS/SSL server and client if the communication used a DES/3DES based ciphersuite.
Statement
OpenSSL security update RHSA-2016:1940 mitigates this issue by lowering priority of DES cipher suites so they are not preferred over cipher suites using AES. For compatibility reasons, DES cipher suites remain enabled by default and included in the set of cipher suites identified by the HIGH cipher string. Future updates may move them to MEDIUM or not enable them by default.
NSS addressed this issue by implementing limits on the amount of plain text which can be encrypted by using the same key. Once the limit is reached, the keys will need to be re-negotiated manually. This change will be available in nss-3.27.
GnuTLS is not affected by this issue, since it prioritizes AES before 3DES in the cipher list.
Mitigation
1.SSL/TLS configurations should prefer AES over DES. Versions of OpenSSL shipped with Red Hat Enterprise Linux 6 and 7 already do so. In the version of OpenSSL shipped with Red Hat Enterprise Linux 5, 3DES is listed below the AES-256 cipher and above the AES-128 cipher, therefore AES-256 based ciphersuite should not be disabled on the server.
2. Servers using OpenSSL, should not disable AES-128 and AES-256 ciphersuites. Versions of Apache shipped with Red Hat Enterprise Linux use the default cipher string, in which AES is preferred over DES/3DES based ciphersuites.
For JBoss Middleware, and Java mitigations, please review this knowledge base article:
https://access.redhat.com/articles/2598471
This can be mitigated on OpenShift Container Platform (OCP) by disabling the vulnerable TLS cipher suite in the applicable component. TLS configuration options for OCP are described here:
Common Vulnerability Scoring System (CVSS) Score Details
Info alert:Important note
CVSS scores for open source components depend on vendor-specific factors (e.g. version or build chain). Therefore, Red Hat's score and impact rating can be different from NVD and other vendors. Red Hat remains the authoritative CVE Naming Authority (CNA) source for its products and services (see Red Hat classifications).
CVSS v3 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 7.5 | 7.5 | 7.5 |
| Attack Vector | Network | Network | Network |
| Attack Complexity | Low | Low | Low |
| Privileges Required | None | None | None |
| User Interaction | None | None | None |
| Scope | Unchanged | Unchanged | Unchanged |
| Confidentiality | High | High | High |
| Integrity Impact | None | None | None |
| Availability Impact | None | None | None |
Vector
Red Hat: CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
NVD: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
cve.org: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
CVSS v2 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 4.3 | 5 | N/A |
| Attack Vector | Network | Network | N/A |
| Access Complexity | Medium | Low | N/A |
| Authentication | None | None | N/A |
| Confidentiality Impact | Partial | Partial | N/A |
| Integrity Impact | None | None | N/A |
| Availability Impact | None | None | N/A |
Vector
Red Hat: AV:N/AC:M/Au:N/C:P/I:N/A:N
NVD: AV:N/AC:L/Au:N/C:P/I:N/A:N
Understanding the Weakness (CWE)
Confidentiality
Technical Impact: Read Application Data
The confidentiality of sensitive data may be compromised by the use of a broken or risky cryptographic algorithm.
Integrity
Technical Impact: Modify Application Data
The integrity of sensitive data may be compromised by the use of a broken or risky cryptographic algorithm.
Accountability,Non-Repudiation
Technical Impact: Hide Activities
If the cryptographic algorithm is used to ensure the identity of the source of the data (such as digital signatures), then a broken algorithm will compromise this scheme and the source of the data cannot be proven.
Acknowledgements
Red Hat would like to thank OpenVPN for reporting this issue. Upstream acknowledges Gaëtan Leurent (Inria) and Karthikeyan Bhargavan (Inria) as the original reporters.
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