CVE-2015-5600

Description

It was discovered that the OpenSSH sshd daemon did not check the list of keyboard-interactive authentication methods for duplicates. A remote attacker could use this flaw to bypass the MaxAuthTries limit, making it easier to perform password guessing attacks.

Statement

This issue does not affect the default OpenSSH sshd configuration in Red Hat Enterprise Linux 4, 5, 6 and 7.

Mitigation

This issue can be mitigated by disabling keyboard-interactive authentication method. That can be achieved by setting "ChallengeResponseAuthentication no" in the /etc/ssh/sshd_config configuration file and restarting the sshd service.

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 v2 Score Breakdown

Red HatNVDcve.org
Base Score4.38.5N/A
Attack VectorNetworkNetworkN/A
Access ComplexityMediumLowN/A
AuthenticationNoneNoneN/A
Confidentiality ImpactNonePartialN/A
Integrity ImpactPartialNoneN/A
Availability ImpactNoneCompleteN/A

Vector

Red Hat: AV:N/AC:M/Au:N/C:N/I:P/A:N

NVD: AV:N/AC:L/Au:N/C:P/I:N/A:C

Understanding the Weakness (CWE)

CWE-304

Access Control,Integrity,Confidentiality

Technical Impact: Bypass Protection Mechanism; Gain Privileges or Assume Identity; Read Application Data; Execute Unauthorized Code or Commands

This weakness can lead to the exposure of resources or functionality to unintended actors, possibly providing attackers with sensitive information or allowing attackers to execute arbitrary code.

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