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nessusThis script is Copyright (C) 2021-2024 and is owned by Tenable, Inc. or an Affiliate thereof.DEBIAN_DSA-4861.NASL
HistoryFeb 23, 2021 - 12:00 a.m.

Debian DSA-4861-1 : screen - security update

2021-02-2300:00:00
This script is Copyright (C) 2021-2024 and is owned by Tenable, Inc. or an Affiliate thereof.
www.tenable.com
10

7.5 High

CVSS2

Attack Vector

NETWORK

Attack Complexity

LOW

Authentication

NONE

Confidentiality Impact

PARTIAL

Integrity Impact

PARTIAL

Availability Impact

PARTIAL

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

9.8 High

CVSS3

Attack Vector

NETWORK

Attack Complexity

LOW

Privileges Required

NONE

User Interaction

NONE

Scope

UNCHANGED

Confidentiality Impact

HIGH

Integrity Impact

HIGH

Availability Impact

HIGH

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

9.7 High

AI Score

Confidence

High

0.015 Low

EPSS

Percentile

86.7%

Felix Weinmann reported a flaw in the handling of combining characters in screen, a terminal multiplexer with VT100/ANSI terminal emulation, which can result in denial of service, or potentially the execution of arbitrary code via a specially crafted UTF-8 character sequence.

#
# (C) Tenable Network Security, Inc.
#
# The descriptive text and package checks in this plugin were  
# extracted from Debian Security Advisory DSA-4861. The text 
# itself is copyright (C) Software in the Public Interest, Inc.
#

include('compat.inc');

if (description)
{
  script_id(146791);
  script_version("1.3");
  script_set_attribute(attribute:"plugin_modification_date", value:"2024/01/19");

  script_cve_id("CVE-2021-26937");
  script_xref(name:"DSA", value:"4861");

  script_name(english:"Debian DSA-4861-1 : screen - security update");

  script_set_attribute(attribute:"synopsis", value:
"The remote Debian host is missing a security-related update.");
  script_set_attribute(attribute:"description", value:
"Felix Weinmann reported a flaw in the handling of combining characters
in screen, a terminal multiplexer with VT100/ANSI terminal emulation,
which can result in denial of service, or potentially the execution of
arbitrary code via a specially crafted UTF-8 character sequence.");
  script_set_attribute(attribute:"see_also", value:"https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=982435");
  script_set_attribute(attribute:"see_also", value:"https://security-tracker.debian.org/tracker/source-package/screen");
  script_set_attribute(attribute:"see_also", value:"https://packages.debian.org/source/buster/screen");
  script_set_attribute(attribute:"see_also", value:"https://www.debian.org/security/2021/dsa-4861");
  script_set_attribute(attribute:"solution", value:
"Upgrade the screen packages.

For the stable distribution (buster), this problem has been fixed in
version 4.6.2-3+deb10u1.");
  script_set_cvss_base_vector("CVSS2#AV:N/AC:L/Au:N/C:P/I:P/A:P");
  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:N/S:U/C:H/I:H/A:H");
  script_set_cvss3_temporal_vector("CVSS:3.0/E:P/RL:O/RC:C");
  script_set_attribute(attribute:"cvss_score_source", value:"CVE-2021-26937");

  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:"2021/02/09");
  script_set_attribute(attribute:"patch_publication_date", value:"2021/02/21");
  script_set_attribute(attribute:"plugin_publication_date", value:"2021/02/23");

  script_set_attribute(attribute:"plugin_type", value:"local");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:debian:debian_linux:screen");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:debian:debian_linux:10.0");
  script_set_attribute(attribute:"generated_plugin", value:"current");
  script_end_attributes();

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

  script_copyright(english:"This script is Copyright (C) 2021-2024 and is owned by Tenable, Inc. or an Affiliate thereof.");

  script_dependencies("ssh_get_info.nasl");
  script_require_keys("Host/local_checks_enabled", "Host/Debian/release", "Host/Debian/dpkg-l");

  exit(0);
}


include("audit.inc");
include("debian_package.inc");


if (!get_kb_item("Host/local_checks_enabled")) audit(AUDIT_LOCAL_CHECKS_NOT_ENABLED);
if (!get_kb_item("Host/Debian/release")) audit(AUDIT_OS_NOT, "Debian");
if (!get_kb_item("Host/Debian/dpkg-l")) audit(AUDIT_PACKAGE_LIST_MISSING);


flag = 0;
if (deb_check(release:"10.0", prefix:"screen", reference:"4.6.2-3+deb10u1")) flag++;
if (deb_check(release:"10.0", prefix:"screen-udeb", reference:"4.6.2-3+deb10u1")) flag++;

if (flag)
{
  if (report_verbosity > 0) security_hole(port:0, extra:deb_report_get());
  else security_hole(0);
  exit(0);
}
else audit(AUDIT_HOST_NOT, "affected");
VendorProductVersionCPE
debiandebian_linuxscreenp-cpe:/a:debian:debian_linux:screen
debiandebian_linux10.0cpe:/o:debian:debian_linux:10.0

7.5 High

CVSS2

Attack Vector

NETWORK

Attack Complexity

LOW

Authentication

NONE

Confidentiality Impact

PARTIAL

Integrity Impact

PARTIAL

Availability Impact

PARTIAL

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

9.8 High

CVSS3

Attack Vector

NETWORK

Attack Complexity

LOW

Privileges Required

NONE

User Interaction

NONE

Scope

UNCHANGED

Confidentiality Impact

HIGH

Integrity Impact

HIGH

Availability Impact

HIGH

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

9.7 High

AI Score

Confidence

High

0.015 Low

EPSS

Percentile

86.7%