CVE-2017-12340 Vulnerability Analysis & Exploit Details

CVE-2017-12340
Vulnerability Scoring

4.2
/10
Medium Risk

The vulnerability CVE-2017-12340 could compromise system integrity but typically requires user interaction to be exploited.

Attack Complexity Details

  • Attack Complexity: Low
    Exploits can be performed without significant complexity or special conditions.
  • Attack Vector: Local
    Vulnerability requires local system access.
  • Privileges Required: High
    High-level privileges are required for exploitation.
  • Scope: Unchanged
    Exploit remains within the originally vulnerable component.
  • User Interaction: None
    No user interaction is necessary for exploitation.

CVE-2017-12340 Details

Status: Deferred

Last updated: 🕜 20 Apr 2025, 01:37 UTC
Originally published on: 🕘 30 Nov 2017, 09:29 UTC

Time between publication and last update: 2697 days

CVSS Release: version 3

CVSS3 Source

nvd@nist.gov

CVSS3 Type

Primary

CVSS3 Vector

CVSS:3.0/AV:L/AC:L/PR:H/UI:N/S:U/C:L/I:L/A:L

CVE-2017-12340 Vulnerability Summary

CVE-2017-12340: A vulnerability in Cisco NX-OS System Software running on Cisco MDS Multilayer Director Switches, Cisco Nexus 7000 Series Switches, and Cisco Nexus 7700 Series Switches could allow an authenticated, local attacker to access the Bash shell of an affected device's operating system, even if the Bash shell is disabled on the system. The vulnerability is due to insufficient sanitization of user-supplied parameters that are passed to certain functions of the Python scripting sandbox of the affected system. An attacker could exploit this vulnerability to escape the scripting sandbox and enter the Bash shell of the operating system with the privileges of the authenticated user for the affected system. To exploit this vulnerability, the attacker must have local access to the affected system and be authenticated to the affected system with administrative or Python execution privileges. Cisco Bug IDs: CSCvd86513.

Assessing the Risk of CVE-2017-12340

Access Complexity Graph

The exploitability of CVE-2017-12340 depends on two key factors: attack complexity (the level of effort required to execute an exploit) and privileges required (the access level an attacker needs).

Exploitability Analysis for CVE-2017-12340

The exploitability of CVE-2017-12340 is influenced by multiple factors. Security teams should analyze system configurations and apply appropriate countermeasures to mitigate threats.

Understanding AC and PR

A lower complexity and fewer privilege requirements make exploitation easier. Security teams should evaluate these aspects to determine the urgency of mitigation strategies, such as patch management and access control policies.

Attack Complexity (AC) measures the difficulty in executing an exploit. A high AC means that specific conditions must be met, making an attack more challenging, while a low AC means the vulnerability can be exploited with minimal effort.

Privileges Required (PR) determine the level of system access necessary for an attack. Vulnerabilities requiring no privileges are more accessible to attackers, whereas high privilege requirements limit exploitation to authorized users with elevated access.

CVSS Score Breakdown Chart

Above is the CVSS Sub-score Breakdown for CVE-2017-12340, illustrating how Base, Impact, and Exploitability factors combine to form the overall severity rating. A higher sub-score typically indicates a more severe or easier-to-exploit vulnerability.

CIA Impact Analysis

Below is the Impact Analysis for CVE-2017-12340, showing how Confidentiality, Integrity, and Availability might be affected if the vulnerability is exploited. Higher values usually signal greater potential damage.

  • Confidentiality: Low
    CVE-2017-12340 could lead to minor leaks of non-critical information without major privacy breaches.
  • Integrity: Low
    Exploiting CVE-2017-12340 may cause minor changes to data without severely impacting its accuracy.
  • Availability: Low
    CVE-2017-12340 may slightly degrade system performance without fully affecting service availability.

Exploit Prediction Scoring System (EPSS)

The EPSS score estimates the probability that this vulnerability will be exploited in the near future.

EPSS Score: 0.043% (probability of exploit)

EPSS Percentile: 12.5% (lower percentile = lower relative risk)
This vulnerability is less risky than approximately 87.5% of others.

CVE-2017-12340 References

External References

CWE Common Weakness Enumeration

CWE-116

CAPEC Common Attack Pattern Enumeration and Classification

  • Cross Zone Scripting CAPEC-104 An attacker is able to cause a victim to load content into their web-browser that bypasses security zone controls and gain access to increased privileges to execute scripting code or other web objects such as unsigned ActiveX controls or applets. This is a privilege elevation attack targeted at zone-based web-browser security.
  • User-Controlled Filename CAPEC-73 An attack of this type involves an adversary inserting malicious characters (such as a XSS redirection) into a filename, directly or indirectly that is then used by the target software to generate HTML text or other potentially executable content. Many websites rely on user-generated content and dynamically build resources like files, filenames, and URL links directly from user supplied data. In this attack pattern, the attacker uploads code that can execute in the client browser and/or redirect the client browser to a site that the attacker owns. All XSS attack payload variants can be used to pass and exploit these vulnerabilities.
  • Web Server Logs Tampering CAPEC-81 Web Logs Tampering attacks involve an attacker injecting, deleting or otherwise tampering with the contents of web logs typically for the purposes of masking other malicious behavior. Additionally, writing malicious data to log files may target jobs, filters, reports, and other agents that process the logs in an asynchronous attack pattern. This pattern of attack is similar to "Log Injection-Tampering-Forging" except that in this case, the attack is targeting the logs of the web server and not the application.
  • AJAX Footprinting CAPEC-85 This attack utilizes the frequent client-server roundtrips in Ajax conversation to scan a system. While Ajax does not open up new vulnerabilities per se, it does optimize them from an attacker point of view. A common first step for an attacker is to footprint the target environment to understand what attacks will work. Since footprinting relies on enumeration, the conversational pattern of rapid, multiple requests and responses that are typical in Ajax applications enable an attacker to look for many vulnerabilities, well-known ports, network locations and so on. The knowledge gained through Ajax fingerprinting can be used to support other attacks, such as XSS.

Vulnerable Configurations

  • cpe:2.3:o:cisco:nx-os:8.1\(0.70\)s0:*:*:*:*:*:*:*
    cpe:2.3:o:cisco:nx-os:8.1\(0.70\)s0:*:*:*:*:*:*:*

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