Amazon Linux AMI update for zsh

1) Authorization bypass

EUVDB-ID: #VU14701

Risk: Low

CVSSv3.1: 7 [CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H/E:P/RL:O/RC:C]

CVE-ID: CVE-2018-13259

CWE-ID: CWE-862 - Missing Authorization

Exploit availability: No

Description

The vulnerability allows a local attacker to execute a program without proper authorization on the target system.

The vulnerability exists due to improper truncating of shebang (#!) lines that exceed 64 characters. A local attacker can access the shell and submit a shebang line longer than 64 characters, cause the software to make an execve() call to a program name that is a substring of the intended one and execute a program without proper authorization on the system.

Mitigation

Update the affected packages:

i686:
    zsh-html-5.0.2-33.18.amzn1.i686
    zsh-5.0.2-33.18.amzn1.i686
    zsh-debuginfo-5.0.2-33.18.amzn1.i686

src:
    zsh-5.0.2-33.18.amzn1.src

x86_64:
    zsh-html-5.0.2-33.18.amzn1.x86_64
    zsh-5.0.2-33.18.amzn1.x86_64
    zsh-debuginfo-5.0.2-33.18.amzn1.x86_64

Vulnerable software versions

Amazon Linux AMI: All versions

External links

http://alas.aws.amazon.com/ALAS-2019-1285.html

Q & A

Can this vulnerability be exploited remotely?

No. This vulnerability can be exploited locally. The attacker should have authentication credentials and successfully authenticate on the system.

Is there known malware, which exploits this vulnerability?

No. We are not aware of malware exploiting this vulnerability. However, proof of concept for this vulnerability is available.