Access Restriction Bypass Affecting pam_ssh_agent_auth package, versions <0:0.9.3-9.22.58.amzn1


Severity

Recommended
0.0
medium
0
10

Based on Amazon Linux security rating

    Threat Intelligence

    EPSS
    16.44% (97th percentile)

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  • Snyk ID SNYK-AMZN201803-PAMSSHAGENTAUTH-1692529
  • published 27 Sep 2021
  • disclosed 3 Aug 2015

How to fix?

Upgrade Amazon-Linux:2018.03 pam_ssh_agent_auth to version 0:0.9.3-9.22.58.amzn1 or higher.
This issue was patched in ALAS-2015-625.

NVD Description

Note: Versions mentioned in the description apply only to the upstream pam_ssh_agent_auth package and not the pam_ssh_agent_auth package as distributed by Amazon-Linux. See How to fix? for Amazon-Linux:2018.03 relevant fixed versions and status.

The kbdint_next_device function in auth2-chall.c in sshd in OpenSSH through 6.9 does not properly restrict the processing of keyboard-interactive devices within a single connection, which makes it easier for remote attackers to conduct brute-force attacks or cause a denial of service (CPU consumption) via a long and duplicative list in the ssh -oKbdInteractiveDevices option, as demonstrated by a modified client that provides a different password for each pam element on this list.

References

CVSS Scores

version 3.1
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NVD

8.2 high
  • Attack Vector (AV)
    Network
  • Attack Complexity (AC)
    Low
  • Privileges Required (PR)
    None
  • User Interaction (UI)
    None
  • Scope (S)
    Unchanged
  • Confidentiality (C)
    Low
  • Integrity (I)
    None
  • Availability (A)
    High
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Red Hat

4.3 medium