CVE-2021-25677 Vulnerability Analysis & Exploit Details

CVE-2021-25677
Vulnerability Scoring

5.3
/10
Significant Risk

Security assessments indicate that CVE-2021-25677 presents a notable risk, potentially requiring prompt mitigation.

Attack Complexity Details

  • Attack Complexity: Low
    Exploits can be performed without significant complexity or special conditions.
  • Attack Vector: Network
    Vulnerability is exploitable over a network without physical access.
  • Privileges Required: None
    No 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-2021-25677 Details

Status: Modified

Last updated: 🕠 21 Nov 2024, 05:55 UTC
Originally published on: 🕘 22 Apr 2021, 21:15 UTC

Time between publication and last update: 1308 days

CVSS Release: version 3

CVSS3 Source

productcert@siemens.com

CVSS3 Type

Secondary

CVSS3 Vector

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

CVE-2021-25677 Vulnerability Summary

CVE-2021-25677: A vulnerability has been identified in APOGEE PXC Compact (BACnet) (All versions < V3.5.5), APOGEE PXC Compact (P2 Ethernet) (All versions < V2.8.20), APOGEE PXC Modular (BACnet) (All versions < V3.5.5), APOGEE PXC Modular (P2 Ethernet) (All versions < V2.8.20), Nucleus NET (All versions), Nucleus ReadyStart V3 (All versions < V2017.02.3), Nucleus ReadyStart V3 (All versions < V2017.02.4), Nucleus ReadyStart V4 (All versions < V4.1.0), Nucleus Source Code (Versions including affected DNS modules), SIMOTICS CONNECT 400 (All versions < V0.5.0.0), SIMOTICS CONNECT 400 (All versions >= V0.5.0.0 < V1.0.0.0), TALON TC Compact (BACnet) (All versions < V3.5.5), TALON TC Modular (BACnet) (All versions < V3.5.5). The DNS client does not properly randomize DNS transaction IDs. That could allow an attacker to poison the DNS cache or spoof DNS resolving.

Assessing the Risk of CVE-2021-25677

Access Complexity Graph

The exploitability of CVE-2021-25677 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-2021-25677

With low attack complexity and no required privileges, CVE-2021-25677 is an easy target for cybercriminals. Organizations should prioritize immediate mitigation measures to prevent unauthorized access and data breaches.

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-2021-25677, 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-2021-25677, showing how Confidentiality, Integrity, and Availability might be affected if the vulnerability is exploited. Higher values usually signal greater potential damage.

  • Confidentiality: None
    CVE-2021-25677 has no significant impact on data confidentiality.
  • Integrity: Low
    Exploiting CVE-2021-25677 may cause minor changes to data without severely impacting its accuracy.
  • Availability: None
    CVE-2021-25677 does not impact system availability.

Exploit Prediction Scoring System (EPSS)

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

EPSS Score: 0.139% (probability of exploit)

EPSS Percentile: 50.95% (lower percentile = lower relative risk)
This vulnerability is less risky than approximately 49.05% of others.

CVE-2021-25677 References

External References

CWE Common Weakness Enumeration

CWE-330

CAPEC Common Attack Pattern Enumeration and Classification

  • Brute Force CAPEC-112 In this attack, some asset (information, functionality, identity, etc.) is protected by a finite secret value. The attacker attempts to gain access to this asset by using trial-and-error to exhaustively explore all the possible secret values in the hope of finding the secret (or a value that is functionally equivalent) that will unlock the asset.
  • Signature Spoofing by Key Recreation CAPEC-485 An attacker obtains an authoritative or reputable signer's private signature key by exploiting a cryptographic weakness in the signature algorithm or pseudorandom number generation and then uses this key to forge signatures from the original signer to mislead a victim into performing actions that benefit the attacker.
  • Session Credential Falsification through Prediction CAPEC-59 This attack targets predictable session ID in order to gain privileges. The attacker can predict the session ID used during a transaction to perform spoofing and session hijacking.

Vulnerable Configurations

  • cpe:2.3:o:siemens:simotics_connect_400_firmware:0.5.0.0:*:*:*:*:*:*:*
    cpe:2.3:o:siemens:simotics_connect_400_firmware:0.5.0.0:*:*:*:*:*:*:*
  • cpe:2.3:h:siemens:simotics_connect_400:-:*:*:*:*:*:*:*
    cpe:2.3:h:siemens:simotics_connect_400:-:*:*:*:*:*:*:*
  • cpe:2.3:a:siemens:nucleus_net:*:*:*:*:*:*:*:*
    cpe:2.3:a:siemens:nucleus_net:*:*:*:*:*:*:*:*
  • cpe:2.3:a:siemens:nucleus_readystart_v3:2013.08:*:*:*:*:*:*:*
    cpe:2.3:a:siemens:nucleus_readystart_v3:2013.08:*:*:*:*:*:*:*
  • cpe:2.3:a:siemens:nucleus_readystart_v3:2017.02.3:*:*:*:*:*:*:*
    cpe:2.3:a:siemens:nucleus_readystart_v3:2017.02.3:*:*:*:*:*:*:*
  • cpe:2.3:a:siemens:nucleus_source_code:-:*:*:*:*:*:*:*
    cpe:2.3:a:siemens:nucleus_source_code:-:*:*:*:*:*:*:*

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