Cisco Small Business RV Series Routers Stack-based Buffer Overflow
CVE-2022-20708 is a high-severity improper neutralization of special elements used in an OS command vulnerability in Cisco Small Business RV Series Router Firmware from Cisco, with a CVSS 3.1 base score of 8.0 out of 10. It can be exploited from the same local network by an attacker with a low-privileged account, without any action from a user. CISA added it to the Known Exploited Vulnerabilities catalogue on March 3, 2022, which means attacks have been observed in the wild.
Attackers are already exploiting this vulnerability, according to CISA.
What to do
- Check which version of Cisco Small Business RV Series Router Firmware you run against the affected versions below, and install the vendor's latest release.
- CISA's required action: Apply updates per vendor instructions.
- Read the advisory on tools.cisco.com for workarounds and exact fixed builds.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Cisco | Cisco Small Business RV Series Router Firmware | Not specified in the record | Not stated |
| Cisco | Rv340 Firmware | 1.0.03.24 and earlier | Not stated |
| Cisco | Rv340w Firmware | 1.0.03.24 and earlier | Not stated |
| Cisco | Rv345 Firmware | 1.0.03.24 and earlier | Not stated |
| Cisco | Rv345p Firmware | 1.0.03.24 and earlier | Not stated |
Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.
How the severity score breaks down
- Attack vector
- AdjacentThe attacker must be on the same local network segment.
- Attack complexity
- LowNo special conditions are needed; the attack works reliably.
- Privileges required
- LowA basic user account is enough.
- User interaction
- NoneNo action by a victim is required.
- Scope
- UnchangedImpact stays within the vulnerable component.
- Confidentiality
- HighAll data handled by the component can be read.
- Integrity
- HighData or code can be modified at will.
- Availability
- HighThe component can be taken down completely.
Vector: CVSS:3.1/AV:A/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H. Scored by NVD.
| Scoring system | Score | Severity | Scored by |
|---|---|---|---|
| CVSS 3.1 | 10.0 | Critical | CNA (cisco.com) |
| CVSS 3.1 | 8.0 | High | NVD |
| CVSS 2.0 | 10.0 | High | NVD |
Official description
Multiple vulnerabilities in Cisco Small Business RV160, RV260, RV340, and RV345 Series Routers could allow an attacker to do any of the following: Execute arbitrary code Elevate privileges Execute arbitrary commands Bypass authentication and authorization protections Fetch and run unsigned software Cause denial of service (DoS) For more information about these vulnerabilities, see the Details section of this advisory.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Improper Neutralization of Special Elements used in an OS Command
The product constructs all or part of an OS command using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify the intended OS command before it is sent to a downstream component.
How developers prevent this class of flaw
- If at all possible, use library calls rather than external processes to recreate the desired functionality.
- For any data that will be used to generate a command to be executed, keep as much of that data out of external control as possible. For example, in web applications, this may require storing the data locally in the session's state instead of sending it out to the client in a hidden form field.
- For any security checks that are performed on the client side, ensure that these checks are duplicated on the server side, in order to avoid CWE-602. Attackers can bypass the client-side checks by modifying values after the checks have been performed, or by changing the client to remove the client-side checks entirely. Then, these modified values would be submitted to the server.
More Improper Neutralization of Special Elements used in an OS Command vulnerabilities (CWE-78)
Timeline
- CVE record published.
- Added to CISA's Known Exploited Vulnerabilities catalogue.
- Deadline for US federal agencies to remediate, set by CISA.
- CISA published its SSVC assessment (exploitation: active, automatable: yes, technical impact: total).
- Record last changed materially (score, affected products, status or references).
References
Advisories
Third-party and government advisories
- zerodayinitiative.com/advisories/ZDI-22-417/Third Party Advisory, VDB Entry
- cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2022-20708US Government Resource
Other vulnerabilities in Cisco Small Business RV Series Router Firmware
- 9.1 Critical severity
- 9.1 Critical severity
- 9.1 Critical severity
- 9.1 Critical severity
- 7.2 High severity
- 8.8 High severity
Recent Improper Neutralization of Special Elements used in an OS Command vulnerabilities
- 9.8 Critical severity
- 9.8 Critical severity
- 9.8 Critical severity
- 7.2 High severity
- 8.8 High severity
- 9.8 Critical severity
Spotted an error? Tell us.