Amazon Linux AMI : exim (ALAS-2022-1622)

critical Nessus Plugin ID 163870

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Synopsis

The remote Amazon Linux AMI host is missing a security update.

Description

The version of exim installed on the remote host is prior to 4.92-1.33. It is, therefore, affected by multiple vulnerabilities as referenced in the ALAS-2022-1622 advisory.

Exim 4 before 4.94.2 allows Execution with Unnecessary Privileges. Because Exim operates as root in the log directory (owned by a non-root user), a symlink or hard link attack allows overwriting critical root- owned files anywhere on the filesystem. (CVE-2020-28007)

Exim 4 before 4.94.2 allows Execution with Unnecessary Privileges. Because Exim operates as root in the spool directory (owned by a non-root user), an attacker can write to a /var/spool/exim4/input spool header file, in which a crafted recipient address can indirectly lead to command execution. (CVE-2020-28008)

Exim 4 before 4.94.2 allows Integer Overflow to Buffer Overflow because get_stdinput allows unbounded reads that are accompanied by unbounded increases in a certain size variable. NOTE: exploitation may be impractical because of the execution time needed to overflow (multiple days). (CVE-2020-28009)

Exim 4 before 4.94.2 allows Out-of-bounds Write because the main function, while setuid root, copies the current working directory pathname into a buffer that is too small (on some common platforms).
(CVE-2020-28010)

Exim 4 before 4.94.2 allows Heap-based Buffer Overflow in queue_run via two sender options: -R and -S.
This may cause privilege escalation from exim to root. (CVE-2020-28011)

Exim 4 before 4.94.2 allows Exposure of File Descriptor to Unintended Control Sphere because rda_interpret uses a privileged pipe that lacks a close-on-exec flag. (CVE-2020-28012)

Exim 4 before 4.94.2 allows Heap-based Buffer Overflow because it mishandles -F '.(' on the command line, and thus may allow privilege escalation from any user to root. This occurs because of the interpretation of negative sizes in strncpy. (CVE-2020-28013)

Exim 4 before 4.94.2 allows Execution with Unnecessary Privileges. The -oP option is available to the exim user, and allows a denial of service because root-owned files can be overwritten. (CVE-2020-28014)

Exim 4 before 4.94.2 has Improper Initialization that can lead to recursion-based stack consumption or other consequences. This occurs because use of certain getc functions is mishandled when a client uses BDAT instead of DATA. (CVE-2020-28019)

Exim 4 before 4.94.2 has Improper Restriction of Write Operations within the Bounds of a Memory Buffer.
This occurs when processing name=value pairs within MAIL FROM and RCPT TO commands. (CVE-2020-28022)

Exim 4 before 4.94.2 allows Out-of-bounds Read. smtp_setup_msg may disclose sensitive information from process memory to an unauthenticated SMTP client. (CVE-2020-28023)

Exim 4 before 4.94.2 allows Buffer Underwrite that may result in unauthenticated remote attackers executing arbitrary commands, because smtp_ungetc was only intended to push back characters, but can actually push back non-character error codes such as EOF. (CVE-2020-28024)

Exim 4 before 4.94.2 allows Out-of-bounds Read because pdkim_finish_bodyhash does not validate the relationship between sig->bodyhash.len and b->bh.len; thus, a crafted DKIM-Signature header might lead to a leak of sensitive information from process memory. (CVE-2020-28025)

Exim 4 before 4.94.2 has Improper Neutralization of Line Delimiters, relevant in non-default configurations that enable Delivery Status Notification (DSN). Certain uses of ORCPT= can place a newline into a spool header file, and indirectly allow unauthenticated remote attackers to execute arbitrary commands as root. (CVE-2020-28026)

Exim 4 before 4.94.2 has Execution with Unnecessary Privileges. By leveraging a delete_pid_file race condition, a local user can delete arbitrary files as root. This involves the -oP and -oPX options.
(CVE-2021-27216)

Tenable has extracted the preceding description block directly from the tested product security advisory.

Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version number.

Solution

Run 'yum update exim' to update your system.

Plugin Details

Severity: Critical

ID: 163870

File Name: ala_ALAS-2022-1622.nasl

Version: 1.5

Type: local

Agent: unix

Family: Amazon Linux Local Security Checks

Published: 8/5/2022

Updated: 12/11/2024

Supported Sensors: Agentless Assessment, Continuous Assessment, Frictionless Assessment Agent, Frictionless Assessment AWS, Nessus Agent, Nessus

Risk Information

VPR

Risk Factor: Medium

Score: 6.7

CVSS v2

Risk Factor: High

Base Score: 9.3

Temporal Score: 7.3

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

CVSS Score Source: CVE-2020-28026

CVSS v3

Risk Factor: Critical

Base Score: 9.8

Temporal Score: 8.8

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:P/RL:O/RC:C

Vulnerability Information

CPE: p-cpe:/a:amazon:linux:exim, p-cpe:/a:amazon:linux:exim-debuginfo, p-cpe:/a:amazon:linux:exim-pgsql, p-cpe:/a:amazon:linux:exim-mon, p-cpe:/a:amazon:linux:exim-greylist, cpe:/o:amazon:linux, p-cpe:/a:amazon:linux:exim-mysql

Required KB Items: Host/local_checks_enabled, Host/AmazonLinux/release, Host/AmazonLinux/rpm-list

Exploit Available: true

Exploit Ease: Exploits are available

Patch Publication Date: 7/28/2022

Vulnerability Publication Date: 5/6/2021

Reference Information

CVE: CVE-2020-28007, CVE-2020-28008, CVE-2020-28009, CVE-2020-28010, CVE-2020-28011, CVE-2020-28012, CVE-2020-28013, CVE-2020-28014, CVE-2020-28019, CVE-2020-28022, CVE-2020-28023, CVE-2020-28024, CVE-2020-28025, CVE-2020-28026, CVE-2021-27216

IAVA: 2021-A-0216-S

Detections

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