Amazon Linux 2 : openssl11 (ALAS-2020-1456)

medium Nessus Plugin ID 138622
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VPR Score: 4.4


The remote Amazon Linux 2 host is missing a security update.


In situations where an attacker receives automated notification of the success or failure of a decryption attempt an attacker, after sending a very large number of messages to be decrypted, can recover a CMS/PKCS7 transported encryption key or decrypt any RSA encrypted message that was encrypted with the public RSA key, using a Bleichenbacher padding oracle attack. Applications are not affected if they use a certificate together with the private RSA key to the CMS_decrypt or PKCS7_decrypt functions to select the correct recipient info to decrypt. Fixed in OpenSSL 1.1.1d (Affected 1.1.1-1.1.1c).
Fixed in OpenSSL 1.1.0l (Affected 1.1.0-1.1.0k). Fixed in OpenSSL 1.0.2t (Affected 1.0.2-1.0.2s). (CVE-2019-1563)

Normally in OpenSSL EC groups always have a co-factor present and this is used in side channel resistant code paths. However, in some cases, it is possible to construct a group using explicit parameters (instead of using a named curve). In those cases it is possible that such a group does not have the cofactor present. This can occur even where all the parameters match a known named curve. If such a curve is used then OpenSSL falls back to non-side channel resistant code paths which may result in full key recovery during an ECDSA signature operation.
In order to be vulnerable an attacker would have to have the ability to time the creation of a large number of signatures where explicit parameters with no co-factor present are in use by an application using libcrypto. For the avoidance of doubt libssl is not vulnerable because explicit parameters are never used. Fixed in OpenSSL 1.1.1d (Affected 1.1.1-1.1.1c). Fixed in OpenSSL 1.1.0l (Affected 1.1.0-1.1.0k). Fixed in OpenSSL 1.0.2t (Affected 1.0.2-1.0.2s).

OpenSSL 1.1.1 introduced a rewritten random number generator (RNG).
This was intended to include protection in the event of a fork() system call in order to ensure that the parent and child processes did not share the same RNG state. However this protection was not being used in the default case. A partial mitigation for this issue is that the output from a high precision timer is mixed into the RNG state so the likelihood of a parent and child process sharing state is significantly reduced. If an application already calls OPENSSL_init_crypto() explicitly using OPENSSL_INIT_ATFORK then this problem does not occur at all. Fixed in OpenSSL 1.1.1d (Affected 1.1.1-1.1.1c). (CVE-2019-1549)


Run 'yum update openssl11' to update your system.

See Also

Plugin Details

Severity: Medium

ID: 138622

File Name: al2_ALAS-2020-1456.nasl

Version: 1.2

Type: local

Agent: unix

Published: 7/20/2020

Updated: 7/22/2020

Dependencies: ssh_get_info.nasl

Risk Information

Risk Factor: Medium

VPR Score: 4.4

CVSS v2.0

Base Score: 5

Temporal Score: 3.7

Vector: CVSS2#AV:N/AC:L/Au:N/C:P/I:N/A:N

Temporal Vector: CVSS2#E:U/RL:OF/RC:C

CVSS v3.0

Base Score: 5.3

Temporal Score: 4.6

Vector: CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N

Temporal Vector: CVSS:3.0/E:U/RL:O/RC:C

Vulnerability Information

CPE: cpe:2.3:o:amazon:linux:2:*:*:*:*:*:*:*, p-cpe:2.3:a:amazon:linux:openssl11:*:*:*:*:*:*:*, p-cpe:2.3:a:amazon:linux:openssl11-debuginfo:*:*:*:*:*:*:*, p-cpe:2.3:a:amazon:linux:openssl11-devel:*:*:*:*:*:*:*, p-cpe:2.3:a:amazon:linux:openssl11-libs:*:*:*:*:*:*:*, p-cpe:2.3:a:amazon:linux:openssl11-static:*:*:*:*:*:*:*

Required KB Items: Host/local_checks_enabled, Host/AmazonLinux/release, Host/AmazonLinux/rpm-list

Exploit Ease: No known exploits are available

Patch Publication Date: 7/17/2020

Vulnerability Publication Date: 9/10/2019

Reference Information

CVE: CVE-2019-1549, CVE-2019-1547, CVE-2019-1563

ALAS: 2020-1456