Amazon Linux AMI update for mercurial

1) Remote code execution

EUVDB-ID: #VU7220

Risk: High

CVSSv4.0: 8.7 [CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:A/U:Amber]

CVE-ID: CVE-2017-9462

CWE-ID: CWE-20 - Improper input validation

Exploit availability: Yes

Description

The vulnerability allows a remote authenticated attacker to execute arbitrary code on the target system.

The weakness exists due to improper input validation in "hg serve --stdio". A remote attacker can use --debugger as a repository name and consequently execute arbitrary code with privileges of the current user.

Successful exploitation of the vulnerability may result in system compromise.

Mitigation

Update the affected packages.

i686:
    mercurial-python26-3.7.3-1.28.amzn1.i686
    mercurial-debuginfo-3.7.3-1.28.amzn1.i686
    mercurial-common-3.7.3-1.28.amzn1.i686
    mercurial-python27-3.7.3-1.28.amzn1.i686
    emacs-mercurial-el-3.7.3-1.28.amzn1.i686
    emacs-mercurial-3.7.3-1.28.amzn1.i686

src:
    mercurial-3.7.3-1.28.amzn1.src

x86_64:
    mercurial-python27-3.7.3-1.28.amzn1.x86_64
    mercurial-python26-3.7.3-1.28.amzn1.x86_64
    emacs-mercurial-3.7.3-1.28.amzn1.x86_64
    mercurial-common-3.7.3-1.28.amzn1.x86_64
    mercurial-debuginfo-3.7.3-1.28.amzn1.x86_64
    emacs-mercurial-el-3.7.3-1.28.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-2017-856.html

Q & A

Can this vulnerability be exploited remotely?

Yes. This vulnerability can be exploited by a remote authenticated user via the Internet.

Is there known malware, which exploits this vulnerability?

No. We are not aware of malware exploiting this vulnerability. However, a fully functional exploit for this vulnerability is available.