CVE-2018-6794 : Detail

CVE-2018-6794

5.3
/
Medium
39.4%V4
Network
2018-02-07
04h00 +00:00
2018-12-05
09h57 +00:00
CVE.org
NVD
Notifications for a CVE
Stay informed of any changes for a specific CVE.
Notifications manage

CVE Descriptions

Suricata before 4.0.4 is prone to an HTTP detection bypass vulnerability in detect.c and stream-tcp.c. If a malicious server breaks a normal TCP flow and sends data before the 3-way handshake is complete, then the data sent by the malicious server will be accepted by web clients such as a web browser or Linux CLI utilities, but ignored by Suricata IDS signatures. This mostly affects IDS signatures for the HTTP protocol and TCP stream content; signatures for TCP packets will inspect such network traffic as usual.

CVE Informations

Related Weaknesses

CWE-ID Weakness Name Source
CWE-693 Protection Mechanism Failure
The product does not use or incorrectly uses a protection mechanism that provides sufficient defense against directed attacks against the product.

Metrics

Metrics Score Severity CVSS Vector Source
V3.0 5.3 MEDIUM CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N

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.

Low

Modification of data is possible, but the attacker does not have control over the consequence of a modification, or the amount of modification is constrained. The data modification does not have a direct, serious impact on the impacted component.

Availability Impact

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

None

There is no impact to availability within the impacted component.

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

 nvd@nist.gov
V2 5 AV:N/AC:L/Au:N/C:N/I:P/A:N nvd@nist.gov

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 : 44247

Publication date : 2018-03-04 23h00 +00:00
Author : Positive Technologies
EDB Verified : No

----------------------------------------------------- Vulnerability Type: Detection Bypass Affected Product: Suricata Vulnerable version: <4.0.4 CVE number: CVE-2018-6794 Found: 25.01.2018 By: Kirill Shipulin (@kirill_wow), Positive Technologies Severity: Medium ------------------------------------------ About Suricata: --------------- Suricata is a high performance Network Threat Detection, IDS, IPS and Network Security Monitoring engine. Open Source and owned by a community run non-profit foundation, the Open Information Security Foundation (OISF). Suricata is developed by the OISF, its supporting vendors and the community Attack Description: ------------------- If as a server side you break a normal TCP 3 way handshake packets order and inject some response data before 3whs is complete then data still will be received by the a client but some IDS engines may skip content checks on that. Attack scenario TCP flow scheme: Client -> [SYN] [Seq=0 Ack= 0] -> Evil Server Client <- [SYN, ACK] [Seq=0 Ack= 1] <- Evil Server Client <- [PSH, ACK] [Seq=1 Ack= 1] <- Evil Server # Injection before the 3whs is completed Client <- [FIN, ACK] [Seq=83 Ack= 1] <- Evil Server Client -> [ACK] [Seq=1 Ack= 84] -> Evil Server Client -> [PSH, ACK] [Seq=1 Ack= 84] -> Evil Server IDS signature checks for tcp stream or http response body will be skipped in the case of data injection. This attack technique requires all three packets from a malicious server to be received by a client side together before it completes 3whs. Proof of concept server was written in C to reproduce this and it works reliably in local networks. Since some network devices may affect packets transmission exploitation is not so reliable for the internet scenario. This attack possibly may impact other network monitoring or intrusion detection systems because is not limited to Suricata IDS: an old Snort IDS version 2.9.4 is also affected. Successful exploitation leads to a complete TCP-Stream response or HTTP response signatures bypass and may be used to prevent malicious payloads from network detection. PoС: ---- A Working PoC server is available here: https://github.com/kirillwow/ids_bypass There is also a traffic capture of this data injection technique. Timeline Summary: ----------------- 2018-01-25: Issue submitted to the bug tracker. 2018-01-30: Patch ready. 2018-02-14: Suricata 4.0.4 containing the fix has been released. References: ----------- CVE-2018-6794 https://redmine.openinfosecfoundation.org/issues/2427 Contacts: --------- Twitter: https://twitter.com/AttackDetection Twitter: https://twitter.com/kirill_wow Telegram: https://t.me/kirill_wow Proof of Concept: https://gitlab.com/exploit-database/exploitdb-bin-sploits/-/raw/main/bin-sploits/44247.zip

Products Mentioned

Configuraton 0

Suricata-ids>>Suricata >> Version To (excluding) 4.0.4

Configuraton 0

Debian>>Debian_linux >> Version 8.0

References

https://www.exploit-db.com/exploits/44247/
Tags : exploit, x_refsource_EXPLOIT-DB
The information presented on CVE Find originates from several carefully selected reference sources. CVE data is provided by MITRE Corporation and the National Vulnerability Database (NVD). The Known Exploited Vulnerabilities (KEV) catalog is sourced from the Cybersecurity and Infrastructure Security Agency (CISA), while EPSS scores come from FIRST.org. Additionally, data regarding software weaknesses (CWE) and common attack patterns (CAPEC) is maintained by MITRE Corporation, and information on hardware and software configurations (CPE) is provided by the NVD.