CVE-2019-11704 : Detail

CVE-2019-11704

9.8
/
Critical
Overflow
29.02%V3
Network
2019-07-23
11h20 +00:00
2019-08-16
17h06 +00:00
CVE.org
NVD
Notifications for a CVE
Stay informed of any changes for a specific CVE.
Notifications manage

CVE Descriptions

A flaw in Thunderbird's implementation of iCal causes a heap buffer overflow in icalmemory_strdup_and_dequote when processing certain email messages, resulting in a potentially exploitable crash. This vulnerability affects Thunderbird < 60.7.1.

CVE Informations

Related Weaknesses

CWE-ID Weakness Name Source
CWE-787 Out-of-bounds Write
The product writes data past the end, or before the beginning, of the intended buffer.

Metrics

Metrics Score Severity CVSS Vector 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.

 [email protected]
V2 7.5 AV:N/AC:L/Au:N/C:P/I:P/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 : 47002

Publication date : 2019-06-16 22h00 +00:00
Author : X41 D-Sec GmbH
EDB Verified : No

X41 D-Sec GmbH Security Advisory: X41-2019-001 Heap-based buffer overflow in Thunderbird ========================================= Severity Rating: High Confirmed Affected Versions: All versions affected Confirmed Patched Versions: Thunderbird ESR 60.7.XXX Vendor: Thunderbird Vendor URL: https://www.thunderbird.net/ Vendor Reference: https://bugzilla.mozilla.org/show_bug.cgi?id=1553814 Vector: Incoming mail with calendar attachment Credit: X41 D-SEC GmbH, Luis Merino Status: Public CVE: CVE-2019-11704 CWE: 122 CVSS Score: 7.8 CVSS Vector: CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:H/E:U/RL:O Advisory-URL: https://www.x41-dsec.de/lab/advisories/x41-2019-001-thunderbird Summary and Impact ================== A heap-based buffer overflow has been identified in the Thunderbird email client. The issue is present in the libical implementation, which was forked from upstream libical version 0.47. The issue can be triggered remotely, when an attacker sends an specially crafted calendar attachment and does not require user interaction. It might be used by a remote attacker to crash or gain remote code execution in the client system. This issue was initially reported by Brandon Perry here: https://bugzilla.mozilla.org/show_bug.cgi?id=1280832 and fixed in libical upstream, but was never fixed in Thunderbird. X41 did not perform a full test or audit on the software. Product Description =================== Thunderbird is a free and open source email, newsfeed, chat, and calendaring client, that's easy to set up and customize. Analysis ======== A heap-based buffer overflow in icalvalue.c icalmemory_strdup_and_dequote() can be triggered while parsing a calendar attachment containing a malformed or specially crafted string. {% highlight c %} static char *icalmemorystrdupanddequote(const char *str) { char *out = (char *)malloc(sizeof(char) * strlen(str) + 1); char *pout = out; // ... for (p = str; *p!=0; p++){ if( *p == '\') { p++; // ... else { *pout = *p; } } {% endhighlight %} Bounds checking in `icalmemorystrdupanddequote()can be bypassed when the inputp` ends with a backslash, which enables an attacker to read out of bounds of the input buffer and writing out of bounds of a heap-allocated output buffer. The issue manifests in several ways, including out of bounds read and write, null-pointer dereference and frequently leads to heap corruption. It is expected that an attacker can exploit this vulnerability to achieve remote code execution. Proof of Concept ================ A reproducer eml file can be found in https://github.com/x41sec/advisories/tree/master/X41-2019-001 Workarounds =========== A fix is available from upstream. Alternatively, libical can be replaced by icaljs, a JavaScript implementation of ical parsing, by setting calendar.icaljs = true in Thunderbird configuration. Timeline ======== 2016-06-19 Issue reported by Brandon Perry to the vendor 2019-05-23 Issue reported by X41 D-SEC to the vendor 2019-05-23 Vendor reply 2019-06-12 CVE IDs assigned 2019-06-13 Patched Version released 2019-06-13 Advisory released About X41 D-SEC GmbH ==================== X41 is an expert provider for application security services. Having extensive industry experience and expertise in the area of information security, a strong core security team of world class security experts enables X41 to perform premium security services. Fields of expertise in the area of application security are security centered code reviews, binary reverse engineering and vulnerability discovery. Custom research and a IT security consulting and support services are core competencies of X41. Proof of Concept: https://gitlab.com/exploit-database/exploitdb-bin-sploits/-/raw/main/bin-sploits/47002.zip

Products Mentioned

Configuraton 0

Mozilla>>Thunderbird >> Version To (excluding) 60.7.1

References

https://security.gentoo.org/glsa/201908-20
Tags : vendor-advisory, x_refsource_GENTOO