Amazon Linux 2 : curl (ALAS-2021-1700)

medium Nessus Plugin ID 153416

Synopsis

The remote Amazon Linux 2 host is missing a security update.

Description

The version of curl installed on the remote host is prior to 7.76.1-7. It is, therefore, affected by multiple vulnerabilities as referenced in the ALAS2-2021-1700 advisory.

- curl 7.7 through 7.76.1 suffers from an information disclosure when the `-t` command line option, known as `CURLOPT_TELNETOPTIONS` in libcurl, is used to send variable=content pairs to TELNET servers. Due to a flaw in the option parser for sending NEW_ENV variables, libcurl could be made to pass on uninitialized data from a stack based buffer to the server, resulting in potentially revealing sensitive internal information to the server using a clear-text network protocol. (CVE-2021-22898)

- When curl is instructed to download content using the metalink feature, thecontents is verified against a hash provided in the metalink XML file.The metalink XML file points out to the client how to get the same contentfrom a set of different URLs, potentially hosted by different servers and theclient can then download the file from one or several of them. In a serial orparallel manner.If one of the servers hosting the contents has been breached and the contentsof the specific file on that server is replaced with a modified payload, curlshould detect this when the hash of the file mismatches after a completeddownload.
It should remove the contents and instead try getting the contentsfrom another URL. This is not done, and instead such a hash mismatch is onlymentioned in text and the potentially malicious content is kept in the file ondisk. (CVE-2021-22922)

- When curl is instructed to get content using the metalink feature, and a user name and password are used to download the metalink XML file, those same credentials are then subsequently passed on to each of the servers from which curl will download or try to download the contents from. Often contrary to the user's expectations and intentions and without telling the user it happened. (CVE-2021-22923)

- libcurl keeps previously used connections in a connection pool for subsequenttransfers to reuse, if one of them matches the setup.Due to errors in the logic, the config matching function did not take 'issuercert' into account and it compared the involved paths *case insensitively*,which could lead to libcurl reusing wrong connections.File paths are, or can be, case sensitive on many systems but not all, and caneven vary depending on used file systems.The comparison also didn't include the 'issuer cert' which a transfer can setto qualify how to verify the server certificate. (CVE-2021-22924)

- curl supports the `-t` command line option, known as `CURLOPT_TELNETOPTIONS`in libcurl. This rarely used option is used to send variable=content pairs toTELNET servers.Due to flaw in the option parser for sending `NEW_ENV` variables, libcurlcould be made to pass on uninitialized data from a stack based buffer to theserver. Therefore potentially revealing sensitive internal information to theserver using a clear- text network protocol.This could happen because curl did not call and use sscanf() correctly whenparsing the string provided by the application. (CVE-2021-22925)

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

Solution

Run 'yum update curl' to update your system.

See Also

https://alas.aws.amazon.com/AL2/ALAS-2021-1700.html

https://access.redhat.com/security/cve/CVE-2021-22898

https://access.redhat.com/security/cve/CVE-2021-22922

https://access.redhat.com/security/cve/CVE-2021-22923

https://access.redhat.com/security/cve/CVE-2021-22924

https://access.redhat.com/security/cve/CVE-2021-22925

Plugin Details

Severity: Medium

ID: 153416

File Name: al2_ALAS-2021-1700.nasl

Version: 1.4

Type: local

Agent: unix

Published: 9/16/2021

Updated: 6/7/2022

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

Risk Information

VPR

Risk Factor: Medium

Score: 4.4

CVSS v2

Risk Factor: Medium

Base Score: 5

Temporal Score: 3.7

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

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

CVSS Score Source: CVE-2021-22925

CVSS v3

Risk Factor: Medium

Base Score: 6.5

Temporal Score: 5.7

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

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

CVSS Score Source: CVE-2021-22922

Vulnerability Information

CPE: p-cpe:/a:amazon:linux:curl, p-cpe:/a:amazon:linux:curl-debuginfo, p-cpe:/a:amazon:linux:libcurl, p-cpe:/a:amazon:linux:libcurl-devel, cpe:/o:amazon:linux:2

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

Exploit Ease: No known exploits are available

Patch Publication Date: 9/8/2021

Vulnerability Publication Date: 5/28/2021

Reference Information

CVE: CVE-2021-22898, CVE-2021-22922, CVE-2021-22923, CVE-2021-22924, CVE-2021-22925

IAVA: 2021-A-0352-S

ALAS: 2021-1700