CVE-2021-34756 Vulnerability Analysis & Exploit Details

CVE-2021-34756
Vulnerability Scoring

6.7
/10
High Risk

If left unpatched, CVE-2021-34756 could lead to major system disruptions or data loss.

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-2021-34756 Details

Status: Modified

Last updated: 🕕 21 Nov 2024, 06:11 UTC
Originally published on: 🕖 27 Oct 2021, 19:15 UTC

Time between publication and last update: 1120 days

CVSS Release: version 3

CVSS3 Source

ykramarz@cisco.com

CVSS3 Type

Secondary

CVSS3 Vector

CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H

CVE-2021-34756 Vulnerability Summary

CVE-2021-34756: Multiple vulnerabilities in the CLI of Cisco Firepower Threat Defense (FTD) Software could allow an authenticated, local attacker to execute arbitrary commands with root privileges. For more information about these vulnerabilities, see the Details section of this advisory.

Assessing the Risk of CVE-2021-34756

Access Complexity Graph

The exploitability of CVE-2021-34756 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-2021-34756

The exploitability of CVE-2021-34756 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-2021-34756, 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-2021-34756, showing how Confidentiality, Integrity, and Availability might be affected if the vulnerability is exploited. Higher values usually signal greater potential damage.

  • Confidentiality: High
    Exploiting CVE-2021-34756 can result in unauthorized access to sensitive data, severely compromising data privacy.
  • Integrity: High
    CVE-2021-34756 could allow unauthorized modifications to data, potentially affecting system reliability and trust.
  • Availability: High
    CVE-2021-34756 can disrupt system operations, potentially causing complete denial of service (DoS).

Exploit Prediction Scoring System (EPSS)

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

EPSS Score: 0.042% (probability of exploit)

EPSS Percentile: 5.18% (lower percentile = lower relative risk)
This vulnerability is less risky than approximately 94.82% of others.

CVE-2021-34756 References

External References

CWE Common Weakness Enumeration

CWE-78

CAPEC Common Attack Pattern Enumeration and Classification

  • Command Line Execution through SQL Injection CAPEC-108 An attacker uses standard SQL injection methods to inject data into the command line for execution. This could be done directly through misuse of directives such as MSSQL_xp_cmdshell or indirectly through injection of data into the database that would be interpreted as shell commands. Sometime later, an unscrupulous backend application (or could be part of the functionality of the same application) fetches the injected data stored in the database and uses this data as command line arguments without performing proper validation. The malicious data escapes that data plane by spawning new commands to be executed on the host.
  • Command Delimiters CAPEC-15 An attack of this type exploits a programs' vulnerabilities that allows an attacker's commands to be concatenated onto a legitimate command with the intent of targeting other resources such as the file system or database. The system that uses a filter or denylist input validation, as opposed to allowlist validation is vulnerable to an attacker who predicts delimiters (or combinations of delimiters) not present in the filter or denylist. As with other injection attacks, the attacker uses the command delimiter payload as an entry point to tunnel through the application and activate additional attacks through SQL queries, shell commands, network scanning, and so on.
  • Exploiting Multiple Input Interpretation Layers CAPEC-43 An attacker supplies the target software with input data that contains sequences of special characters designed to bypass input validation logic. This exploit relies on the target making multiples passes over the input data and processing a "layer" of special characters with each pass. In this manner, the attacker can disguise input that would otherwise be rejected as invalid by concealing it with layers of special/escape characters that are stripped off by subsequent processing steps. The goal is to first discover cases where the input validation layer executes before one or more parsing layers. That is, user input may go through the following logic in an application: <parser1> --> <input validator> --> <parser2>. In such cases, the attacker will need to provide input that will pass through the input validator, but after passing through parser2, will be converted into something that the input validator was supposed to stop.
  • Argument Injection CAPEC-6 An attacker changes the behavior or state of a targeted application through injecting data or command syntax through the targets use of non-validated and non-filtered arguments of exposed services or methods.
  • OS Command Injection CAPEC-88 In this type of an attack, an adversary injects operating system commands into existing application functions. An application that uses untrusted input to build command strings is vulnerable. An adversary can leverage OS command injection in an application to elevate privileges, execute arbitrary commands and compromise the underlying operating system.

Vulnerable Configurations

  • cpe:2.3:a:cisco:firepower_management_center_virtual_appliance:6.1.0:*:*:*:*:*:*:*
    cpe:2.3:a:cisco:firepower_management_center_virtual_appliance:6.1.0:*:*:*:*:*:*:*
  • cpe:2.3:a:cisco:firepower_management_center_virtual_appliance:6.2.0:*:*:*:*:*:*:*
    cpe:2.3:a:cisco:firepower_management_center_virtual_appliance:6.2.0:*:*:*:*:*:*:*
  • cpe:2.3:a:cisco:firepower_management_center_virtual_appliance:6.2.3:*:*:*:*:*:*:*
    cpe:2.3:a:cisco:firepower_management_center_virtual_appliance:6.2.3:*:*:*:*:*:*:*
  • cpe:2.3:a:cisco:firepower_management_center_virtual_appliance:6.3.0:*:*:*:*:*:*:*
    cpe:2.3:a:cisco:firepower_management_center_virtual_appliance:6.3.0:*:*:*:*:*:*:*
  • cpe:2.3:a:cisco:firepower_management_center_virtual_appliance:6.4.0:*:*:*:*:*:*:*
    cpe:2.3:a:cisco:firepower_management_center_virtual_appliance:6.4.0:*:*:*:*:*:*:*
  • cpe:2.3:a:cisco:firepower_management_center_virtual_appliance:6.4.0.11:*:*:*:*:*:*:*
    cpe:2.3:a:cisco:firepower_management_center_virtual_appliance:6.4.0.11:*:*:*:*:*:*:*
  • cpe:2.3:a:cisco:firepower_management_center_virtual_appliance:6.5.0:*:*:*:*:*:*:*
    cpe:2.3:a:cisco:firepower_management_center_virtual_appliance:6.5.0:*:*:*:*:*:*:*
  • cpe:2.3:a:cisco:firepower_management_center_virtual_appliance:6.6.0:*:*:*:*:*:*:*
    cpe:2.3:a:cisco:firepower_management_center_virtual_appliance:6.6.0:*:*:*:*:*:*:*
  • cpe:2.3:a:cisco:firepower_management_center_virtual_appliance:6.6.1:*:*:*:*:*:*:*
    cpe:2.3:a:cisco:firepower_management_center_virtual_appliance:6.6.1:*:*:*:*:*:*:*
  • cpe:2.3:a:cisco:firepower_management_center_virtual_appliance:6.7.0:*:*:*:*:*:*:*
    cpe:2.3:a:cisco:firepower_management_center_virtual_appliance:6.7.0:*:*:*:*:*:*:*
  • cpe:2.3:a:cisco:firepower_management_center_virtual_appliance:7.0.0:*:*:*:*:*:*:*
    cpe:2.3:a:cisco:firepower_management_center_virtual_appliance:7.0.0:*:*:*:*:*:*:*
  • cpe:2.3:a:cisco:firepower_management_center_virtual_appliance:7.1.0:*:*:*:*:*:*:*
    cpe:2.3:a:cisco:firepower_management_center_virtual_appliance:7.1.0:*:*:*:*:*:*:*
  • cpe:2.3:a:cisco:firepower_threat_defense:6.4.0:*:*:*:*:*:*:*
    cpe:2.3:a:cisco:firepower_threat_defense:6.4.0:*:*:*:*:*:*:*
  • cpe:2.3:a:cisco:firepower_threat_defense:6.4.0.1:*:*:*:*:*:*:*
    cpe:2.3:a:cisco:firepower_threat_defense:6.4.0.1:*:*:*:*:*:*:*
  • cpe:2.3:a:cisco:firepower_threat_defense:6.4.0.2:*:*:*:*:*:*:*
    cpe:2.3:a:cisco:firepower_threat_defense:6.4.0.2:*:*:*:*:*:*:*
  • cpe:2.3:a:cisco:firepower_threat_defense:6.4.0.3:*:*:*:*:*:*:*
    cpe:2.3:a:cisco:firepower_threat_defense:6.4.0.3:*:*:*:*:*:*:*
  • cpe:2.3:a:cisco:firepower_threat_defense:6.4.0.4:*:*:*:*:*:*:*
    cpe:2.3:a:cisco:firepower_threat_defense:6.4.0.4:*:*:*:*:*:*:*
  • cpe:2.3:a:cisco:firepower_threat_defense:6.4.0.5:*:*:*:*:*:*:*
    cpe:2.3:a:cisco:firepower_threat_defense:6.4.0.5:*:*:*:*:*:*:*
  • cpe:2.3:a:cisco:firepower_threat_defense:6.4.0.6:*:*:*:*:*:*:*
    cpe:2.3:a:cisco:firepower_threat_defense:6.4.0.6:*:*:*:*:*:*:*
  • cpe:2.3:a:cisco:firepower_threat_defense:6.4.0.7:*:*:*:*:*:*:*
    cpe:2.3:a:cisco:firepower_threat_defense:6.4.0.7:*:*:*:*:*:*:*
  • cpe:2.3:a:cisco:firepower_threat_defense:6.4.0.8:*:*:*:*:*:*:*
    cpe:2.3:a:cisco:firepower_threat_defense:6.4.0.8:*:*:*:*:*:*:*
  • cpe:2.3:a:cisco:firepower_threat_defense:6.4.0.9:*:*:*:*:*:*:*
    cpe:2.3:a:cisco:firepower_threat_defense:6.4.0.9:*:*:*:*:*:*:*
  • cpe:2.3:a:cisco:firepower_threat_defense:6.4.0.10:*:*:*:*:*:*:*
    cpe:2.3:a:cisco:firepower_threat_defense:6.4.0.10:*:*:*:*:*:*:*
  • cpe:2.3:a:cisco:firepower_threat_defense:6.4.0.11:*:*:*:*:*:*:*
    cpe:2.3:a:cisco:firepower_threat_defense:6.4.0.11:*:*:*:*:*:*:*
  • cpe:2.3:a:cisco:firepower_threat_defense:6.4.0.12:*:*:*:*:*:*:*
    cpe:2.3:a:cisco:firepower_threat_defense:6.4.0.12:*:*:*:*:*:*:*
  • cpe:2.3:a:cisco:firepower_threat_defense:6.6.0:*:*:*:*:*:*:*
    cpe:2.3:a:cisco:firepower_threat_defense:6.6.0:*:*:*:*:*:*:*
  • cpe:2.3:a:cisco:firepower_threat_defense:6.6.0.1:*:*:*:*:*:*:*
    cpe:2.3:a:cisco:firepower_threat_defense:6.6.0.1:*:*:*:*:*:*:*
  • cpe:2.3:a:cisco:firepower_threat_defense:6.6.1:*:*:*:*:*:*:*
    cpe:2.3:a:cisco:firepower_threat_defense:6.6.1:*:*:*:*:*:*:*
  • cpe:2.3:a:cisco:firepower_threat_defense:6.6.3:*:*:*:*:*:*:*
    cpe:2.3:a:cisco:firepower_threat_defense:6.6.3:*:*:*:*:*:*:*
  • cpe:2.3:a:cisco:firepower_threat_defense:6.6.4:*:*:*:*:*:*:*
    cpe:2.3:a:cisco:firepower_threat_defense:6.6.4:*:*:*:*:*:*:*
  • cpe:2.3:a:cisco:firepower_threat_defense:6.7.0:*:*:*:*:*:*:*
    cpe:2.3:a:cisco:firepower_threat_defense:6.7.0:*:*:*:*:*:*:*
  • cpe:2.3:a:cisco:firepower_threat_defense:6.7.0.1:*:*:*:*:*:*:*
    cpe:2.3:a:cisco:firepower_threat_defense:6.7.0.1:*:*:*:*:*:*:*
  • cpe:2.3:a:cisco:firepower_threat_defense:6.7.0.2:*:*:*:*:*:*:*
    cpe:2.3:a:cisco:firepower_threat_defense:6.7.0.2:*:*:*:*:*:*:*
  • cpe:2.3:a:cisco:firepower_threat_defense:7.0.0:*:*:*:*:*:*:*
    cpe:2.3:a:cisco:firepower_threat_defense:7.0.0:*:*:*:*:*:*:*
  • cpe:2.3:a:cisco:firepower_threat_defense:7.0.0.1:*:*:*:*:*:*:*
    cpe:2.3:a:cisco:firepower_threat_defense:7.0.0.1:*:*:*:*:*:*:*
  • cpe:2.3:a:cisco:sourcefire_defense_center:6.1.0:*:*:*:*:*:*:*
    cpe:2.3:a:cisco:sourcefire_defense_center:6.1.0:*:*:*:*:*:*:*
  • cpe:2.3:a:cisco:sourcefire_defense_center:6.2.0:*:*:*:*:*:*:*
    cpe:2.3:a:cisco:sourcefire_defense_center:6.2.0:*:*:*:*:*:*:*
  • cpe:2.3:a:cisco:sourcefire_defense_center:6.2.3:*:*:*:*:*:*:*
    cpe:2.3:a:cisco:sourcefire_defense_center:6.2.3:*:*:*:*:*:*:*
  • cpe:2.3:a:cisco:sourcefire_defense_center:6.3.0:*:*:*:*:*:*:*
    cpe:2.3:a:cisco:sourcefire_defense_center:6.3.0:*:*:*:*:*:*:*
  • cpe:2.3:a:cisco:sourcefire_defense_center:6.4.0:*:*:*:*:*:*:*
    cpe:2.3:a:cisco:sourcefire_defense_center:6.4.0:*:*:*:*:*:*:*
  • cpe:2.3:a:cisco:sourcefire_defense_center:6.4.0.11:*:*:*:*:*:*:*
    cpe:2.3:a:cisco:sourcefire_defense_center:6.4.0.11:*:*:*:*:*:*:*
  • cpe:2.3:a:cisco:sourcefire_defense_center:6.5.0:*:*:*:*:*:*:*
    cpe:2.3:a:cisco:sourcefire_defense_center:6.5.0:*:*:*:*:*:*:*
  • cpe:2.3:a:cisco:sourcefire_defense_center:6.6.0:*:*:*:*:*:*:*
    cpe:2.3:a:cisco:sourcefire_defense_center:6.6.0:*:*:*:*:*:*:*
  • cpe:2.3:a:cisco:sourcefire_defense_center:6.6.1:*:*:*:*:*:*:*
    cpe:2.3:a:cisco:sourcefire_defense_center:6.6.1:*:*:*:*:*:*:*
  • cpe:2.3:a:cisco:sourcefire_defense_center:6.7.0:*:*:*:*:*:*:*
    cpe:2.3:a:cisco:sourcefire_defense_center:6.7.0:*:*:*:*:*:*:*
  • cpe:2.3:a:cisco:sourcefire_defense_center:7.0.0:*:*:*:*:*:*:*
    cpe:2.3:a:cisco:sourcefire_defense_center:7.0.0:*:*:*:*:*:*:*
  • cpe:2.3:a:cisco:sourcefire_defense_center:7.1.0:*:*:*:*:*:*:*
    cpe:2.3:a:cisco:sourcefire_defense_center:7.1.0:*:*:*:*:*:*:*

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