CVE-2017-12231
Cisco IOS Software Network Address Translation Denial-of-Service Vulnerability
Description
CVE-2017-12231 is a high-severity vulnerability affecting Cisco IOS software, carrying a CVSS 3.1 base score of 7.5. This vulnerability allows an attacker to cause a denial of service condition on the affected device by exploiting improper handling in the software's processing logic. This CVE has been added to CISA's Known Exploited Vulnerabilities (KEV) catalog on 2022-03-03, confirming active exploitation in the wild with a federal remediation deadline of 2022-03-24. With an EPSS score of 6.8% (91.20th percentile), the probability of exploitation activity is above average compared to other known vulnerabilities.
KEV Information
CVSS Score
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:HOpen in CalculatorCWEs
Affected Products
| Vendor | Product | Version |
|---|---|---|
| cisco | ios | >= 12.4, <= 15.6 |
Multiple CVSS Assessments
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
References
- http://www.securityfocus.com/bid/101039(Broken Link, Third Party Advisory, VDB Entry)
- http://www.securitytracker.com/id/1039449(Broken Link, Third Party Advisory, VDB Entry)
- https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20170927-nat(Vendor Advisory)
- https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2017-12231(US Government Resource)
Weakness Type
CWE-399: CWE-399
The vulnerability identified as CVE-2017-12231 relates to a weakness in Cisco IOS software where the software fails to properly handle certain operations, leading to a security condition that can be exploited by an attacker. While the specific CWE classification may not have detailed context available, the nature of the vulnerability — allowing denial of service — indicates a fundamental flaw in how the software processes or validates certain input or operations. This type of weakness is commonly found in complex software products where the interaction between components creates opportunities for exploitation.
In the context of Cisco IOS software, this weakness is particularly concerning because it can be exploited remotely over the network without requiring physical access to the target system. The high severity rating and its inclusion in the CISA KEV catalog reflect the real-world danger this weakness poses. Organizations should treat this vulnerability with high urgency, applying vendor-provided patches and implementing defense-in-depth measures to mitigate the risk of exploitation. The presence of this weakness in Cisco's product highlights the ongoing challenge of maintaining secure software in complex enterprise environments.
Learn more: CWE-399
Impact Analysis
CVE-2017-12231 carries a CVSS 3.1 base score of 7.5 (HIGH), reflecting its significant potential for harm across multiple impact dimensions.
Confidentiality (NONE): The vulnerability does not directly impact the confidentiality of data on the affected system. However, in multi-stage attack scenarios, this vulnerability may be combined with other exploits to eventually access sensitive information.
Integrity (NONE): There is no direct integrity impact from this vulnerability. The attacker cannot modify data or system configurations through this exploit vector alone.
Availability (HIGH): The vulnerability can be leveraged to completely disrupt the availability of the affected service or device. An attacker can force a system crash, trigger a reload, or render the device inoperable, causing significant operational disruption. For critical infrastructure components like network devices or security appliances, even brief availability outages can have cascading effects across the organization.
Scope (Unchanged): The scope is Unchanged, meaning the impact of the vulnerability is limited to the affected component itself. While the consequences within that component can be severe, the exploitation does not directly extend to other systems or security domains.
The EPSS score of 6.8% (91.20th percentile) indicates a moderate exploitation probability relative to other vulnerabilities, though its KEV listing confirms that active exploitation has occurred.
Exploit Maturity
CVE-2017-12231 has confirmed active exploitation in the wild, as evidenced by its inclusion in CISA's Known Exploited Vulnerabilities catalog.
Active Exploitation: This vulnerability was added to the CISA KEV catalog on 2022-03-03, confirming that threat actors have actively exploited it in real-world attacks against organizations. The KEV listing represents a high-confidence indicator of exploitation, as CISA requires evidence of active exploitation before adding vulnerabilities to this catalog. Federal agencies were required to remediate this vulnerability by the deadline of 2022-03-24.
Ransomware Association: According to the CISA KEV catalog, this vulnerability has not been specifically linked to known ransomware campaigns at this time. However, the confirmed active exploitation means that threat actors are leveraging this vulnerability for other objectives such as espionage, data theft, or establishing persistent footholds within target networks.
Public Exploits: While specific public exploit code may not be widely cataloged in standard databases, the KEV listing confirms that exploitation is occurring in the wild. Threat actors may be using privately developed exploit tools or leveraging the vulnerability through commercial exploit frameworks.
EPSS Score: The EPSS score of 6.8% (91.20th percentile) reflects a measurable exploitation probability. While not in the highest tier, the KEV listing confirms real-world exploitation has been observed.
KEV Remediation Deadline: 2022-03-24. Federal agencies under BOD 22-01 were required to remediate by this date, and all organizations are strongly encouraged to treat this deadline as a benchmark for their own patch management timelines.
Remediation
- Apply the vendor-provided security update immediately. Follow the guidance in the official security advisory: Vendor Advisory. This is the primary remediation action specified in the CISA KEV catalog: "Apply updates per vendor instructions." Ensure all affected versions are upgraded to a patched release as soon as possible.
- Verify all affected product versions are addressed. The following products and versions are known to be vulnerable: cisco ios (>= 12.4, <= 15.6). Conduct an inventory of your environment to identify all instances of these products and ensure each one receives the appropriate update.
- Restrict network access to the affected service. While patches are being deployed, use firewall rules and access control lists to limit network exposure of the vulnerable service. Ensure that only authorized hosts and networks can reach the affected ports and protocols.
- Deploy intrusion detection signatures for known exploitation patterns. Update IDS/IPS rulesets to include detection for exploitation attempts targeting this vulnerability. Monitor network traffic for suspicious patterns consistent with the attack vector.
- Monitor affected systems for signs of prior compromise. Before or during patching, review system and security logs for indicators of exploitation. Given the confirmed KEV listing, there is a realistic possibility that unpatched systems may have already been targeted. Conduct forensic analysis if anomalies are detected.
- Establish ongoing patch management practices for this product. Ensure Cisco security advisories are monitored continuously. Subscribe to vendor notification channels and integrate patch testing and deployment into your organization's vulnerability management lifecycle to prevent future exposure windows.
Technical Details
CVE-2017-12231 is a high-severity vulnerability in Cisco IOS software that can cause a denial of service condition through exploitation of a weakness in the software processing logic. The vulnerability exists in the way Cisco IOS software handles certain network-facing operations, where insufficient validation or improper processing of incoming requests or data allows an attacker to trigger the vulnerable condition.
The attack vector is Network (AV:N), meaning exploitation can occur remotely over the network without physical access. The attack complexity is low complexity (AC:L), indicating that reliable exploitation does not require specialized conditions or preparation beyond having access to the attack vector. The vulnerability requires no privileges (PR:N) and no user interaction (UI:N).
The scope is Unchanged (S:U), indicating the impact is contained within the vulnerable component's own security scope. The combined impact ratings of NONE/NONE/HIGH for Confidentiality/Integrity/Availability reflect the high-severity nature of this flaw. The technical root cause involves improper handling within the affected component, resulting in a condition that threat actors can reliably trigger to achieve their exploitation objectives. Affected products include: cisco ios (versions: >= 12.4, <= 15.6).
Frequently Asked Questions
Is CVE-2017-12231 actively exploited?
Yes, CVE-2017-12231 is confirmed to be actively exploited in the wild. It was added to CISA's Known Exploited Vulnerabilities (KEV) catalog on 2022-03-03, which requires evidence of active exploitation before a vulnerability can be listed. While not specifically linked to ransomware campaigns at this time, the confirmed exploitation means threat actors are leveraging it for various malicious objectives. The EPSS score of 6.8% (91.20th percentile) further underscores the high likelihood of ongoing exploitation activity. Organizations should treat this as an urgent security issue requiring immediate attention.
What products are affected by CVE-2017-12231?
CVE-2017-12231 affects Cisco IOS software. Specifically, the following product versions have been identified as vulnerable: cisco ios (versions: >= 12.4, <= 15.6). Organizations should conduct a thorough inventory of their environments to identify all deployments of the affected software. Both production systems and development or staging environments should be included in this assessment, as any unpatched instance represents a potential entry point for attackers.
How do I fix CVE-2017-12231?
Apply the security update provided by Cisco according to their official advisory. The vendor advisory is available at: https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20170927-nat. Ensure all instances of the affected product in your environment are updated to a patched version. While deploying patches, implement compensating controls such as network access restrictions and enhanced monitoring to reduce exploitation risk. After remediation, verify that the patch was successfully applied and review system logs for any indicators of prior compromise, as unpatched systems may have been targeted before the fix was deployed.
How severe is CVE-2017-12231?
CVE-2017-12231 is rated HIGH with a CVSS 3.1 base score of 7.5. The vulnerability can be exploited remotely over the network, with low attack complexity, and does not require user interaction. The impact on availability is particularly significant. Its inclusion in the CISA KEV catalog with a remediation deadline of 2022-03-24 confirms the real-world severity. The EPSS score of 6.8% places it in the 91.20th percentile for exploitation likelihood.
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