Amazon Linux AMI update for krb5

1) Reachable Assertion

EUVDB-ID: #VU17350

Risk: Low

CVSSv4.0: 6.6 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:U/U:Clear]

CVE-ID: CVE-2018-20217

CWE-ID: CWE-617 - Reachable Assertion

Exploit availability: No

Description

The vulnerability allows a remote attacker to perform a denial of service (DoS) attack.

The vulnerability exists due to a reachable assertion in in the KDC. A remote attacker can obtain a krbtgt ticket using an older encryption type (single-DES, triple-DES, or RC4) and crash the KDC by making an S4U2Self request.

Mitigation

Update the affected packages:

i686:
    krb5-debuginfo-1.15.1-46.48.amzn1.i686
    krb5-devel-1.15.1-46.48.amzn1.i686
    libkadm5-1.15.1-46.48.amzn1.i686
    krb5-server-ldap-1.15.1-46.48.amzn1.i686
    krb5-server-1.15.1-46.48.amzn1.i686
    krb5-workstation-1.15.1-46.48.amzn1.i686
    krb5-pkinit-openssl-1.15.1-46.48.amzn1.i686
    krb5-libs-1.15.1-46.48.amzn1.i686

src:
    krb5-1.15.1-46.48.amzn1.src

x86_64:
    krb5-workstation-1.15.1-46.48.amzn1.x86_64
    krb5-libs-1.15.1-46.48.amzn1.x86_64
    libkadm5-1.15.1-46.48.amzn1.x86_64
    krb5-server-ldap-1.15.1-46.48.amzn1.x86_64
    krb5-server-1.15.1-46.48.amzn1.x86_64
    krb5-devel-1.15.1-46.48.amzn1.x86_64
    krb5-pkinit-openssl-1.15.1-46.48.amzn1.x86_64
    krb5-debuginfo-1.15.1-46.48.amzn1.x86_64

Vulnerable software versions

Amazon Linux AMI: All versions

CPE2.3

• cpe:2.3:o:amazon_web_services:amazon_linux_ami:*:*:*:*:*:*:*:*

External links

https://alas.aws.amazon.com/ALAS-2020-1374.html

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.