Cisco IOS Software SSH Version 2 RSA-Based User Authentication Bypass Vulnerability (cisco-sa-20150923-sshpk)

# SPDX-FileCopyrightText: 2016 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:/o:cisco:ios";

if (description)
{
  script_oid("1.3.6.1.4.1.25623.1.0.105640");
  script_version("2026-02-02T05:59:28+0000");
  script_tag(name:"last_modification", value:"2026-02-02 05:59:28 +0000 (Mon, 02 Feb 2026)");
  script_tag(name:"creation_date", value:"2016-05-03 19:31:26 +0200 (Tue, 03 May 2016)");
  script_tag(name:"cvss_base", value:"9.3");
  script_tag(name:"cvss_base_vector", value:"AV:N/AC:M/Au:N/C:C/I:C/A:C");

  script_cve_id("CVE-2015-6280");

  script_tag(name:"qod_type", value:"remote_banner");

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

  script_name("Cisco IOS Software SSH Version 2 RSA-Based User Authentication Bypass Vulnerability (cisco-sa-20150923-sshpk)");

  script_category(ACT_GATHER_INFO);

  script_copyright("Copyright (C) 2016 Greenbone AG");
  script_family("CISCO");
  script_dependencies("gb_cisco_ios_consolidation.nasl");
  script_mandatory_keys("cisco/ios/detected");

  script_tag(name:"summary", value:"A vulnerability in the SSH version 2 (SSHv2) protocol
  implementation of Cisco IOS Software could allow an unauthenticated, remote attacker to bypass
  user authentication.");

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

  script_tag(name:"insight", value:"The vulnerability is due to a flaw in the implementation of the
  SSHv2 public key authentication method, also known as Rivest, Shamir, and Adleman (RSA)-based
  user authentication. An attacker could exploit this vulnerability by authenticating to an
  affected system configured for SSHv2 RSA-based user authentication using a crafted private key.
  The attacker must know a valid username configured for RSA-based user authentication and the
  public key configured for that user to exploit this vulnerability.");

  script_tag(name:"impact", value:"A successful exploit could allow the attacker to bypass user
  authentication and log in with the privileges of the user or with the privileges configured for
  the virtual teletype (VTY) line. Depending on the configuration of the user and of the VTY line,
  the attacker may obtain administrative privileges on the system. The attacker cannot use this
  vulnerability to elevate privileges.");

  script_tag(name:"solution", value:"See the referenced vendor advisory for a solution.");

  script_xref(name:"URL", value:"https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20150923-sshpk");

  exit(0);
}

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

if( ! version = get_app_version( cpe:CPE, nofork:TRUE ) )
  exit( 0 );

affected = make_list(
  "15.2(2)E",
  "15.2(2)E1",
  "15.2(2)E2",
  "15.2(2a)E1",
  "15.2(2a)E2",
  "15.2(3)E",
  "15.2(3a)E",
  "15.2(2)EA1",
  "15.2(3)EA",
  "15.2(1)SY",
  "15.2(1)SY0a",
  "15.3(3)M1",
  "15.3(3)M2",
  "15.3(3)M3",
  "15.3(3)M4",
  "15.3(3)M5",
  "15.3(3)S",
  "15.3(3)S1",
  "15.3(3)S1a",
  "15.3(3)S2",
  "15.3(3)S3",
  "15.3(3)S4",
  "15.3(3)S5",
  "15.4(1)CG",
  "15.4(1)CG1",
  "15.4(2)CG",
  "15.4(3)M",
  "15.4(3)M1",
  "15.4(3)M2",
  "15.4(1)S",
  "15.4(1)S1",
  "15.4(1)S2",
  "15.4(1)S3",
  "15.4(2)S",
  "15.4(2)S1",
  "15.4(2)S2",
  "15.4(3)S",
  "15.4(3)S1",
  "15.4(3)S2",
  "15.4(1)T",
  "15.4(1)T1",
  "15.4(1)T2",
  "15.4(1)T3",
  "15.4(2)T",
  "15.4(2)T1",
  "15.4(2)T2",
  "15.5(1)S",
  "15.5(1)T" );

foreach af ( affected ) {
  if( version == af ) {
    report = report_fixed_ver( installed_version:version, fixed_version: "See advisory" );
    security_message( port:0, data:report );
    exit( 0 );
  }
}

exit( 99 );