Amazon Linux AMI update for exim

1) OS Command Injection

EUVDB-ID: #VU20924

Risk: High

CVSSv3.1: 8.8 [CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H/E:P/RL:O/RC:C]

CVE-ID: CVE-2019-15846

CWE-ID: CWE-78 - Improper Neutralization of Special Elements used in an OS Command ('OS Command Injection')

Exploit availability: Yes

Description

The vulnerability allows a remote attacker to execute arbitrary shell commands on the target system.

The vulnerability exists due to incorrect processing of trailing backslash during TLS connection. A remote unauthenticated attacker can send specially crafted command via an established TLS connection and execute arbitrary OS commands on the target system with root privileges.

Successful exploitation of this vulnerability may result in complete compromise of vulnerable system.

Mitigation

Update the affected packages:

i686:
    exim-pgsql-4.92-1.25.amzn1.i686
    exim-4.92-1.25.amzn1.i686
    exim-debuginfo-4.92-1.25.amzn1.i686
    exim-greylist-4.92-1.25.amzn1.i686
    exim-mon-4.92-1.25.amzn1.i686
    exim-mysql-4.92-1.25.amzn1.i686

src:
    exim-4.92-1.25.amzn1.src

x86_64:
    exim-debuginfo-4.92-1.25.amzn1.x86_64
    exim-greylist-4.92-1.25.amzn1.x86_64
    exim-4.92-1.25.amzn1.x86_64
    exim-pgsql-4.92-1.25.amzn1.x86_64
    exim-mon-4.92-1.25.amzn1.x86_64
    exim-mysql-4.92-1.25.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

http://alas.aws.amazon.com/ALAS-2019-1310.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. However, proof of concept for this vulnerability is available.

2) Heap-based buffer overflow

EUVDB-ID: #VU21399

Risk: High

CVSSv3.1: 9.4 [CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H/E:H/RL:O/RC:C]

CVE-ID: CVE-2019-16928

CWE-ID: CWE-122 - Heap-based Buffer Overflow

Exploit availability: No

Description

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

The vulnerability exists due to a boundary error within the string_vformat() function in string.c when processing an overly long argument for EHLO command. A remote non-authenticated attacker can send a very long string as an argument for the EHLO command, trigger a heap-based buffer overflow and execute arbitrary code on the target system.

Successful exploitation of this vulnerability may result in complete compromise of vulnerable system.

Mitigation

Update the affected packages:

i686:
    exim-pgsql-4.92-1.25.amzn1.i686
    exim-4.92-1.25.amzn1.i686
    exim-debuginfo-4.92-1.25.amzn1.i686
    exim-greylist-4.92-1.25.amzn1.i686
    exim-mon-4.92-1.25.amzn1.i686
    exim-mysql-4.92-1.25.amzn1.i686

src:
    exim-4.92-1.25.amzn1.src

x86_64:
    exim-debuginfo-4.92-1.25.amzn1.x86_64
    exim-greylist-4.92-1.25.amzn1.x86_64
    exim-4.92-1.25.amzn1.x86_64
    exim-pgsql-4.92-1.25.amzn1.x86_64
    exim-mon-4.92-1.25.amzn1.x86_64
    exim-mysql-4.92-1.25.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

http://alas.aws.amazon.com/ALAS-2019-1310.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?

Yes. This vulnerability is being exploited in the wild.