CVE-2019-11184
Description
A flaw has been discovered in which an attacker can infer SSH keystrokes when after a victim connects to a compromised host. The attacker must compromise a server that the victim is connecting to and be able to groom the CPU cache on the system prior to or while a connection is in progress. The attack uses RDMA to groom the cache then measures the response time of cache access to aid in statistical likelihood of an educated guess of keystroke input. This flaw has been branded "NetCat".
Statement
While the affected software can be run on a Red Hat Enterrprise Linux server, this flaw is not created or solvable at the operating system level. Connecting to an untrusted or compromised host can lead to any information sent to it being stolen.
Mitigation
This particular attack requires the compromised server to use RDMA and a Intel Xeon CPU. The Intel Xeon CPU family has a specific feature (DDIO) that allows RDMA to use CPU internal cache to improve RDMA performance. The client connecting to the compromised server does not need to use RDMA or DDIO.
- This attack is similar to connecting to any other compromised/untrusted host; any untrusted system could already log SSH input.
- RDMA is designed to not require operating system interaction, its interactions are between the network card and system hardware. If this functionality is compromised the operating system is unable to affect changes here.
While this attack vector does seem unlikely, Red Hat recommends following Intel's instructions. Connecting to a compromised host is not recommended. Red Hat products can 'run' on the affected system but the system design is not something that is solvable in Red Hat products.
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).
The following CVSS metrics and score provided are preliminary and subject to review.
CVSS v3 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 2.3 | 4.8 | N/A |
| Attack Vector | Adjacent Network | Adjacent Network | N/A |
| Attack Complexity | High | High | N/A |
| Privileges Required | Low | Low | N/A |
| User Interaction | Required | None | N/A |
| Scope | Unchanged | Unchanged | N/A |
| Confidentiality | Low | High | N/A |
| Integrity Impact | None | None | N/A |
| Availability Impact | None | None | N/A |
Vector
Red Hat: CVSS:3.0/AV:A/AC:H/PR:L/UI:R/S:U/C:L/I:N/A:N
NVD: CVSS:3.1/AV:A/AC:H/PR:L/UI:N/S:U/C:H/I:N/A:N
Understanding the Weakness (CWE)
Confidentiality,Other
Technical Impact: Read Application Data; Other
Information exposure.
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