Linux: Hidden executables

# SPDX-FileCopyrightText: 2020 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

if(description)
{
  script_oid("1.3.6.1.4.1.25623.1.0.150104");
  script_version("2023-07-27T05:05:09+0000");
  script_tag(name:"last_modification", value:"2023-07-27 05:05:09 +0000 (Thu, 27 Jul 2023)");
  script_tag(name:"creation_date", value:"2020-01-28 09:58:33 +0100 (Tue, 28 Jan 2020)");
  script_tag(name:"cvss_base", value:"0.0");
  script_tag(name:"cvss_base_vector", value:"AV:L/AC:H/Au:S/C:N/I:N/A:N");
  script_tag(name:"qod", value:"97");

  script_name("Linux: Hidden executables");

  script_category(ACT_GATHER_INFO);
  script_copyright("Copyright (C) 2020 Greenbone AG");
  script_family("Policy");
  script_dependencies("gb_gnu_bash_detect_lin.nasl", "compliance_tests.nasl");
  script_mandatory_keys("Compliance/Launch");
  script_exclude_keys("ssh/no_linux_shell");

  script_xref(name:"URL", value:"https://linoxide.com/how-tos/stickbit-suid-guid/");

  script_tag(name:"summary", value:"Malicious programs, code, and scripts usually start with a dot
(.) to hide themselves.

Note: This script dramatically increases the scan duration.");

  exit(0);
}

include("ssh_func.inc");
include("policy_functions.inc");

cmd = "find / -type f -executable";
title = "Hidden executables";
solution = "Inspect file and remove if necessary.";
test_type = "SSH_Cmd";
default = "None";
comment = "";

if(!get_kb_item("login/SSH/success") || !sock = ssh_login_or_reuse_connection()){
  value = "Error";
  compliant = "incomplete";
  comment = "No SSH connection";
}else if (!get_kb_item("bash/linux/detected")){
  value = "Error";
  compliant = "incomplete";
  comment = "Bash is not available on the target host but needed for this test.";
}else{
  compliant = "yes";
  ssh_cmd = "/bin/bash -c 'for f in $(find / -type f -executable -print 2>/dev/null); do if [[ $(basename $f) == .* ]]; then echo $f; fi; done'";
  files = ssh_cmd(cmd:ssh_cmd, socket:sock, nosh:TRUE);
  if(files){
    compliant = "no";
    files_list = split(files, keep:FALSE);
    foreach file (files_list){
      value += "," + file;
    }
  }

  if(value)
    value = str_replace(string:value, find:',', replace:'', count:1);
  else
    value= "None";
}

policy_reporting(result:value, default:default, compliant:compliant, fixtext:solution,
  type:test_type, test:cmd, info:comment);
policy_set_kbs(type:test_type, cmd:cmd, default:default, solution:solution, title:title,
  value:value, compliant:compliant);

exit(0);