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nessusThis script is Copyright (C) 2021-2023 and is owned by Tenable, Inc. or an Affiliate thereof.EULEROS_SA-2021-2707.NASL
HistoryNov 11, 2021 - 12:00 a.m.

EulerOS 2.0 SP9 : curl (EulerOS-SA-2021-2707)

2021-11-1100:00:00
This script is Copyright (C) 2021-2023 and is owned by Tenable, Inc. or an Affiliate thereof.
www.tenable.com
21
euleros 2.0
sp9
curl
metalink
hash verification
xml
credentials
connection pool
command line option
tls library
secure transport
certificate vulnerability

CVSS2

5

Attack Vector

NETWORK

Attack Complexity

LOW

Authentication

NONE

Confidentiality Impact

NONE

Integrity Impact

NONE

Availability Impact

PARTIAL

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

CVSS3

7.5

Attack Vector

NETWORK

Attack Complexity

LOW

Privileges Required

NONE

User Interaction

NONE

Scope

UNCHANGED

Confidentiality Impact

NONE

Integrity Impact

NONE

Availability Impact

HIGH

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

AI Score

6.8

Confidence

Low

EPSS

0.005

Percentile

76.5%

According to the versions of the curl packages installed, the EulerOS installation on the remote host is affected by the following vulnerabilities :

  • 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_TELNETOPTIONSin 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)

  • libcurl-using applications can ask for a specific client certificate to be used in a transfer. This is done with the CURLOPT_SSLCERT option (--cert with the command line tool).When libcurl is built to use the macOS native TLS library Secure Transport, an application can ask for the client certificate by name or with a file name - using the same option. If the name exists as a file, it will be used instead of by name.If the appliction runs with a current working directory that is writable by other users (like /tmp), a malicious user can create a file name with the same name as the app wants to use by name, and thereby trick the application to use the file based cert instead of the one referred to by name making libcurl send the wrong client certificate in the TLS connection handshake. (CVE-2021-22926)

Note that Tenable Network Security has extracted the preceding description block directly from the EulerOS security advisory. Tenable has attempted to automatically clean and format it as much as possible without introducing additional issues.

#%NASL_MIN_LEVEL 70300
##
# (C) Tenable Network Security, Inc.
##

include('deprecated_nasl_level.inc');
include('compat.inc');

if (description)
{
  script_id(155263);
  script_version("1.6");
  script_set_attribute(attribute:"plugin_modification_date", value:"2023/11/24");

  script_cve_id(
    "CVE-2021-22922",
    "CVE-2021-22923",
    "CVE-2021-22924",
    "CVE-2021-22925",
    "CVE-2021-22926"
  );
  script_xref(name:"IAVA", value:"2021-A-0437-S");
  script_xref(name:"IAVA", value:"2021-A-0352-S");

  script_name(english:"EulerOS 2.0 SP9 : curl (EulerOS-SA-2021-2707)");

  script_set_attribute(attribute:"synopsis", value:
"The remote EulerOS host is missing multiple security updates.");
  script_set_attribute(attribute:"description", value:
"According to the versions of the curl packages installed, the EulerOS installation on the remote host is affected by the
following vulnerabilities :

  - 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)

  - libcurl-using applications can ask for a specific client certificate to be used in a transfer. This is
    done with the `CURLOPT_SSLCERT` option (`--cert` with the command line tool).When libcurl is built to use
    the macOS native TLS library Secure Transport, an application can ask for the client certificate by name
    or with a file name - using the same option. If the name exists as a file, it will be used instead of by
    name.If the appliction runs with a current working directory that is writable by other users (like
    `/tmp`), a malicious user can create a file name with the same name as the app wants to use by name, and
    thereby trick the application to use the file based cert instead of the one referred to by name making
    libcurl send the wrong client certificate in the TLS connection handshake. (CVE-2021-22926)

Note that Tenable Network Security has extracted the preceding description block directly from the EulerOS security
advisory. Tenable has attempted to automatically clean and format it as much as possible without introducing additional
issues.");
  # https://developer.huaweicloud.com/ict/en/site-euleros/euleros/security-advisories/EulerOS-SA-2021-2707
  script_set_attribute(attribute:"see_also", value:"http://www.nessus.org/u?3bd55e3c");
  script_set_attribute(attribute:"solution", value:
"Update the affected curl packages.");
  script_set_cvss_base_vector("CVSS2#AV:N/AC:L/Au:N/C:P/I:N/A:N");
  script_set_cvss_temporal_vector("CVSS2#E:POC/RL:OF/RC:C");
  script_set_cvss3_base_vector("CVSS:3.0/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:N");
  script_set_cvss3_temporal_vector("CVSS:3.0/E:P/RL:O/RC:C");
  script_set_attribute(attribute:"cvss_score_source", value:"CVE-2021-22925");
  script_set_attribute(attribute:"cvss3_score_source", value:"CVE-2021-22922");

  script_set_attribute(attribute:"exploitability_ease", value:"Exploits are available");
  script_set_attribute(attribute:"exploit_available", value:"true");

  script_set_attribute(attribute:"vuln_publication_date", value:"2021/07/24");
  script_set_attribute(attribute:"patch_publication_date", value:"2021/11/11");
  script_set_attribute(attribute:"plugin_publication_date", value:"2021/11/11");

  script_set_attribute(attribute:"plugin_type", value:"local");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:huawei:euleros:curl");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:huawei:euleros:libcurl");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:huawei:euleros:2.0");
  script_set_attribute(attribute:"stig_severity", value:"I");
  script_end_attributes();

  script_category(ACT_GATHER_INFO);
  script_family(english:"Huawei Local Security Checks");

  script_copyright(english:"This script is Copyright (C) 2021-2023 and is owned by Tenable, Inc. or an Affiliate thereof.");

  script_dependencies("ssh_get_info.nasl");
  script_require_keys("Host/local_checks_enabled", "Host/EulerOS/release", "Host/EulerOS/rpm-list", "Host/EulerOS/sp");
  script_exclude_keys("Host/EulerOS/uvp_version");

  exit(0);
}

include("audit.inc");
include("global_settings.inc");
include("rpm.inc");

if (!get_kb_item("Host/local_checks_enabled")) audit(AUDIT_LOCAL_CHECKS_NOT_ENABLED);

var release = get_kb_item("Host/EulerOS/release");
if (isnull(release) || release !~ "^EulerOS") audit(AUDIT_OS_NOT, "EulerOS");
var uvp = get_kb_item("Host/EulerOS/uvp_version");
if (release !~ "^EulerOS release 2\.0(\D|$)") audit(AUDIT_OS_NOT, "EulerOS 2.0 SP9");

var sp = get_kb_item("Host/EulerOS/sp");
if (isnull(sp) || sp !~ "^(9)$") audit(AUDIT_OS_NOT, "EulerOS 2.0 SP9");

if (!empty_or_null(uvp)) audit(AUDIT_OS_NOT, "EulerOS 2.0 SP9", "EulerOS UVP " + uvp);

if (!get_kb_item("Host/EulerOS/rpm-list")) audit(AUDIT_PACKAGE_LIST_MISSING);

var cpu = get_kb_item("Host/cpu");
if (isnull(cpu)) audit(AUDIT_UNKNOWN_ARCH);
if ("x86_64" >!< cpu && cpu !~ "^i[3-6]86$" && "aarch64" >!< cpu) audit(AUDIT_LOCAL_CHECKS_NOT_IMPLEMENTED, "EulerOS", cpu);
if ("x86_64" >!< cpu && cpu !~ "^i[3-6]86$") audit(AUDIT_ARCH_NOT, "i686 / x86_64", cpu);

var flag = 0;

var pkgs = [
  "curl-7.69.1-2.h10.eulerosv2r9",
  "libcurl-7.69.1-2.h10.eulerosv2r9"
];

foreach (var pkg in pkgs)
  if (rpm_check(release:"EulerOS-2.0", sp:"9", reference:pkg)) flag++;

if (flag)
{
  security_report_v4(
    port       : 0,
    severity   : SECURITY_WARNING,
    extra      : rpm_report_get()
  );
  exit(0);
}
else
{
  var tested = pkg_tests_get();
  if (tested) audit(AUDIT_PACKAGE_NOT_AFFECTED, tested);
  else audit(AUDIT_PACKAGE_NOT_INSTALLED, "curl");
}

CVSS2

5

Attack Vector

NETWORK

Attack Complexity

LOW

Authentication

NONE

Confidentiality Impact

NONE

Integrity Impact

NONE

Availability Impact

PARTIAL

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

CVSS3

7.5

Attack Vector

NETWORK

Attack Complexity

LOW

Privileges Required

NONE

User Interaction

NONE

Scope

UNCHANGED

Confidentiality Impact

NONE

Integrity Impact

NONE

Availability Impact

HIGH

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

AI Score

6.8

Confidence

Low

EPSS

0.005

Percentile

76.5%