Vulnerability identifier: #VU29487

Vulnerability risk: Medium

CVSSv3.1: 5.3 [CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N/E:U/RL:O/RC:C]

CVE-ID: CVE-2020-14002

CWE-ID: CWE-300

Exploitation vector: Network

Exploit availability: No

Vulnerable software:
PuTTY
Client/Desktop applications / Software for system administration

Vendor: Simon Tatham

Description

The vulnerability allows a remote attacker to perform a Man-in-the-Middle (MitM) attack.

The vulnerability exists due to an observable discrepancy issue in the algorithm negotiation. This allows man-in-the-middle attackers to target initial connection attempts (where no host key for the server has been cached by the client).

Mitigation
Install updates from vendor's website.

Vulnerable software versions

PuTTY: 0.68 - 0.73

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External links
http://lists.tartarus.org/pipermail/putty-announce/
http://www.chiark.greenend.org.uk/~sgtatham/putty/changes.html
http://www.fzi.de/en/news/news/detail-en/artikel/fsa-2020-2-ausnutzung-eines-informationslecks-fuer-gezielte-mitm-angriffe-auf-ssh-clients/

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Q & A

Can this vulnerability be exploited remotely?

Yes. This vulnerability can be exploited by a remote non-authenticated attacker via the Internet.

Is there known malware, which exploits this vulnerability?

No. We are not aware of malware exploiting this vulnerability.