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openvasCopyright (C) 2017 Greenbone AGOPENVAS:1361412562310812051
HistoryOct 27, 2017 - 12:00 a.m.

OpenSSH 'sftp-server' Security Bypass Vulnerability - Linux

2017-10-2700:00:00
Copyright (C) 2017 Greenbone AG
plugins.openvas.org
1926

5.3 Medium

CVSS3

Attack Vector

NETWORK

Attack Complexity

LOW

Privileges Required

NONE

User Interaction

NONE

Scope

UNCHANGED

Confidentiality Impact

NONE

Integrity Impact

LOW

Availability Impact

NONE

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

5.8 Medium

AI Score

Confidence

High

5 Medium

CVSS2

Access Vector

Access Complexity

Authentication

NONE

Confidentiality Impact

NONE

Integrity Impact

PARTIAL

Availability Impact

NONE

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

0.007 Low

EPSS

Percentile

79.6%

openssh is prone to a security bypass vulnerability.

# SPDX-FileCopyrightText: 2017 Greenbone AG
# Some text descriptions might be excerpted from (a) referenced
# source(s), and are Copyright (C) by the respective right holder(s).
#
# SPDX-License-Identifier: GPL-2.0-only

CPE = "cpe:/a:openbsd:openssh";

if(description)
{
  script_oid("1.3.6.1.4.1.25623.1.0.812051");
  script_version("2024-02-15T05:05:40+0000");
  script_cve_id("CVE-2017-15906");
  script_tag(name:"cvss_base", value:"5.0");
  script_tag(name:"cvss_base_vector", value:"AV:N/AC:L/Au:N/C:N/I:P/A:N");
  script_tag(name:"last_modification", value:"2024-02-15 05:05:40 +0000 (Thu, 15 Feb 2024)");
  script_tag(name:"severity_vector", value:"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N");
  script_tag(name:"severity_origin", value:"NVD");
  script_tag(name:"severity_date", value:"2022-08-18 13:49:00 +0000 (Thu, 18 Aug 2022)");
  script_tag(name:"creation_date", value:"2017-10-27 13:08:12 +0530 (Fri, 27 Oct 2017)");
  script_name("OpenSSH 'sftp-server' Security Bypass Vulnerability - Linux");
  script_copyright("Copyright (C) 2017 Greenbone AG");
  script_category(ACT_GATHER_INFO);
  script_family("General");
  script_dependencies("gb_openssh_consolidation.nasl", "os_detection.nasl");
  script_mandatory_keys("openssh/detected", "Host/runs_unixoide");

  script_xref(name:"URL", value:"https://www.openssh.com/txt/release-7.6");
  script_xref(name:"URL", value:"http://www.securityfocus.com/bid/101552");
  script_xref(name:"URL", value:"https://github.com/openbsd/src/commit/a6981567e8e");

  script_tag(name:"summary", value:"openssh is prone to a security bypass vulnerability.");

  script_tag(name:"vuldetect", value:"Checks if a vulnerable version is present on the target host.");

  script_tag(name:"insight", value:"The flaw exists in the 'process_open' function
  in sftp-server.c script which does not properly prevent write operations in
  readonly mode.");

  script_tag(name:"impact", value:"Successfully exploiting this issue allows
  local users to bypass certain security restrictions and perform unauthorized
  actions. This may lead to further attacks.");

  script_tag(name:"affected", value:"OpenSSH versions before 7.6 on Linux");

  script_tag(name:"solution", value:"Upgrade to OpenSSH version 7.6 or later.");

  script_tag(name:"solution_type", value:"VendorFix");
  script_tag(name:"qod_type", value:"remote_banner_unreliable");

  exit(0);
}

include("version_func.inc");
include("host_details.inc");

if(isnull(port = get_app_port(cpe:CPE)))
  exit(0);

if(!infos = get_app_version_and_location(cpe:CPE, port:port, exit_no_version:TRUE))
  exit(0);

vers = infos["version"];
path = infos["location"];

deb_vers = get_kb_item("openssh/" + port + "/debian_version");
if(deb_vers && version_is_greater_equal(version:deb_vers, test_version:"7.4p1-10+deb9u3"))
  exit(99);

if(version_is_less(version:vers, test_version:"7.6")) {
  report = report_fixed_ver(installed_version:vers, fixed_version:"7.6", install_path:path);
  security_message(port:port, data:report);
  exit(0);
}

exit(99);

5.3 Medium

CVSS3

Attack Vector

NETWORK

Attack Complexity

LOW

Privileges Required

NONE

User Interaction

NONE

Scope

UNCHANGED

Confidentiality Impact

NONE

Integrity Impact

LOW

Availability Impact

NONE

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

5.8 Medium

AI Score

Confidence

High

5 Medium

CVSS2

Access Vector

Access Complexity

Authentication

NONE

Confidentiality Impact

NONE

Integrity Impact

PARTIAL

Availability Impact

NONE

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

0.007 Low

EPSS

Percentile

79.6%