Exim < 4.89.1 Use-After-Free BDAT Remote Code Execution

Critical Nessus Plugin ID 104815

Synopsis

The remote mail server is potentially affected by a remote code execution flaw.

Description

According to its banner and supported extensions, the remote installation of Exim is affected by a code execution flaw. The implementation of the BDAT SMTP verb for sending large binary messages introduced in Exim 4.88 can incorrectly free an in-use region of memory, leading to memory corruption and potentially allowing an attacker to execute code.

Solution

Update to Exim 4.89.1 or later, or Exim 4.90-RC3 or later. If you cannot upgrade, edit your Exim configuration and set 'chunking_advertise_hosts' to an empty value as a workaround.

See Also

https://lists.exim.org/lurker/message/20171125.034842.d1d75cac.en.html

Plugin Details

Severity: Critical

ID: 104815

File Name: exim_bdat_chunk_uaf.nasl

Version: 1.4

Type: remote

Published: 2017/11/29

Updated: 2018/07/10

Dependencies: 10263

Risk Information

Risk Factor: Critical

CVSS v2.0

Base Score: 10

Temporal Score: 7.4

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

Temporal Vector: CVSS2#E:U/RL:OF/RC:C

CVSS v3.0

Base Score: 9.8

Temporal Score: 8.5

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

Temporal Vector: CVSS:3.0/E:U/RL:O/RC:C

Vulnerability Information

CPE: cpe:/a:exim:exim

Exploit Available: false

Exploit Ease: No known exploits are available

Patch Publication Date: 2017/11/29

Vulnerability Publication Date: 2017/11/24

Reference Information

CVE: CVE-2017-16943