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

high Nessus Plugin ID 104815
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VPR Score: 6.7

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: High

ID: 104815

File Name: exim_bdat_chunk_uaf.nasl

Version: 1.5

Type: remote

Published: 11/29/2017

Updated: 11/12/2019

Dependencies: smtpserver_detect.nasl

Risk Information

Risk Factor: High

VPR Score: 6.7

CVSS Score Source: CVE-2017-16943

CVSS v2.0

Base Score: 7.5

Temporal Score: 5.5

Vector: AV:N/AC:L/Au:N/C:P/I:P/A:P

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

Vulnerability Information

CPE: cpe:/a:exim:exim

Exploit Ease: No known exploits are available

Patch Publication Date: 11/29/2017

Vulnerability Publication Date: 11/24/2017

Reference Information

CVE: CVE-2017-16943