Amazon Linux 2 : openssl (ALAS-2018-1004)

Medium Nessus Plugin ID 109364

Synopsis

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

Description

bn_sqrx8x_internal carry bug on x86_64

There is a carry propagating bug in the x86_64 Montgomery squaring procedure in OpenSSL before 1.0.2m and 1.1.0 before 1.1.0g. No EC algorithms are affected. Analysis suggests that attacks against RSA and DSA as a result of this defect would be very difficult to perform and are not believed likely. Attacks against DH are considered just feasible (although very difficult) because most of the work necessary to deduce information about a private key may be performed offline.
The amount of resources required for such an attack would be very significant and likely only accessible to a limited number of attackers. An attacker would additionally need online access to an unpatched system using the target private key in a scenario with persistent DH parameters and a private key that is shared between multiple clients. This only affects processors that support the BMI1, BMI2 and ADX extensions like Intel Broadwell (5th generation) and later or AMD Ryzen. (CVE-2017-3736)

rsaz_1024_mul_avx2 overflow bug on x86_64

There is an overflow bug in the AVX2 Montgomery multiplication procedure used in exponentiation with 1024-bit moduli. No EC algorithms are affected. Analysis suggests that attacks against RSA and DSA as a result of this defect would be very difficult to perform and are not believed likely. Attacks against DH1024 are considered just feasible, because most of the work necessary to deduce information about a private key may be performed offline. The amount of resources required for such an attack would be significant.
However, for an attack on TLS to be meaningful, the server would have to share the DH1024 private key among multiple clients, which is no longer an option since CVE-2016-0701 . This only affects processors that support the AVX2 but not ADX extensions like Intel Haswell (4th generation). Note: The impact from this issue is similar to CVE-2017-3736 , CVE-2017-3732 and CVE-2015-3193 . OpenSSL version 1.0.2-1.0.2m and 1.1.0-1.1.0g are affected. Fixed in OpenSSL 1.0.2n.
Due to the low severity of this issue we are not issuing a new release of OpenSSL 1.1.0 at this time. The fix will be included in OpenSSL 1.1.0h when it becomes available. The fix is also available in commit e502cc86d in the OpenSSL git repository. (CVE-2017-3738)

RSA key generation cache timing vulnerability in crypto/rsa/rsa_gen.c allows attackers to recover private keys

OpenSSL RSA key generation was found to be vulnerable to cache side-channel attacks. An attacker with sufficient access to mount cache timing attacks during the RSA key generation process could recover parts of the private key. (CVE-2018-0737)

Read/write after SSL object in error state

OpenSSL 1.0.2 (starting from version 1.0.2b) introduced an 'error state' mechanism. The intent was that if a fatal error occurred during a handshake then OpenSSL would move into the error state and would immediately fail if you attempted to continue the handshake. This works as designed for the explicit handshake functions (SSL_do_handshake(), SSL_accept() and SSL_connect()), however due to a bug it does not work correctly if SSL_read() or SSL_write() is called directly. In that scenario, if the handshake fails then a fatal error will be returned in the initial function call. If SSL_read()/SSL_write() is subsequently called by the application for the same SSL object then it will succeed and the data is passed without being decrypted/encrypted directly from the SSL/TLS record layer. In order to exploit this issue an application bug would have to be present that resulted in a call to SSL_read()/SSL_write() being issued after having already received a fatal error. OpenSSL version 1.0.2b-1.0.2m are affected. Fixed in OpenSSL 1.0.2n. OpenSSL 1.1.0 is not affected. (CVE-2017-3737)

Solution

Run 'yum update openssl' to update your system.

See Also

https://alas.aws.amazon.com/AL2/ALAS-2018-1004.html

Plugin Details

Severity: Medium

ID: 109364

File Name: al2_ALAS-2018-1004.nasl

Version: 1.1

Type: local

Agent: unix

Published: 2018/04/27

Updated: 2018/04/27

Dependencies: 12634

Risk Information

Risk Factor: Medium

CVSS v2.0

Base Score: 4.3

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

CVSS v3.0

Base Score: 6.5

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

Vulnerability Information

CPE: p-cpe:/a:amazon:linux:openssl, p-cpe:/a:amazon:linux:openssl-debuginfo, p-cpe:/a:amazon:linux:openssl-devel, p-cpe:/a:amazon:linux:openssl-libs, p-cpe:/a:amazon:linux:openssl-perl, p-cpe:/a:amazon:linux:openssl-static, cpe:/o:amazon:linux:2

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

Patch Publication Date: 2018/04/26

Reference Information

CVE: CVE-2017-3736, CVE-2017-3737, CVE-2017-3738, CVE-2018-0737

ALAS: 2018-1004