D-Link Multiple Routers Command Injection
CVE-2019-16920 is a critical-severity improper neutralization of special elements used in an OS command vulnerability in Dir-655 Firmware from D-Link, with a CVSS 3.1 base score of 9.8 out of 10. It can be exploited remotely over the network by an unauthenticated attacker, without any action from a user. Affected Dir-655 Firmware versions: 3.02b05 and earlier. The record does not name a fixed version, so check the vendor advisory. CISA added it to the Known Exploited Vulnerabilities catalogue on March 25, 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 Dir-655 Firmware you run against the affected versions below, and install the vendor's latest release.
- CISA's required action: The impacted product is end-of-life and should be disconnected if still in use.
- Until you can update, restrict network access to the affected service so it is not reachable from untrusted networks.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| D-Link | Dir-655 Firmware | 3.02b05 and earlier | Not stated |
| D-Link | Dir-866l Firmware | 1.03b04 and earlier | Not stated |
| D-Link | Dir-652 Firmware | Not specified in the record | Not stated |
| D-Link | Dhp-1565 Firmware | 1.01 and earlier | Not stated |
| D-Link | Dir-855l Firmware | Not specified in the record | Not stated |
| D-Link | Dap-1533 Firmware | Not specified in the record | Not stated |
| D-Link | Dir-862l Firmware | Not specified in the record | Not stated |
| D-Link | Dir-615 Firmware | Not specified in the record | Not stated |
| D-Link | Dir-835 Firmware | Not specified in the record | Not stated |
| D-Link | Dir-825 Firmware | Not specified in the record | Not stated |
Version data comes from NVD's product matching. Confirm against the vendor advisory before deciding you are unaffected.
How the severity score breaks down
- Attack vector
- NetworkCan be exploited remotely over a network, including the internet.
- Attack complexity
- LowNo special conditions are needed; the attack works reliably.
- Privileges required
- NoneNo account or login is needed.
- 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:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H. Scored by NVD.
| Scoring system | Score | Severity | Scored by |
|---|---|---|---|
| CVSS 3.1 | 9.8 | Critical | NVD |
| CVSS 3.1 | 9.8 | Critical | CISA (ADP) |
| CVSS 2.0 | 10.0 | High | NVD |
Official description
Unauthenticated remote code execution occurs in D-Link products such as DIR-655C, DIR-866L, DIR-652, and DHP-1565. The issue occurs when the attacker sends an arbitrary input to a "PingTest" device common gateway interface that could lead to common injection. An attacker who successfully triggers the command injection could achieve full system compromise. Later, it was independently found that these are also affected: DIR-855L, DAP-1533, DIR-862L, DIR-615, DIR-835, and DIR-825.
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
Third-party and government advisories
- kb.cert.org/vuls/id/766427Third Party Advisory, US Government Resource
- cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2019-16920US Government Resource
Technical write-ups (may include proof of concept)
- medium.com/%4080vul/determine-the-device-model-affected-by-cve-2019-16920-by-zoomeye-bf6fec7f9bb3Exploit, Third Party Advisory
- seebug.org/vuldb/ssvid-98079Exploit, Third Party Advisory
Other vulnerabilities in Dir-655 Firmware
- 8.8 High severity
Recent Improper Neutralization of Special Elements used in an OS Command vulnerabilities
- 9.8 Critical severity
D-Link DNS-320 Remote Code Execution Exploited
- 8.8 High severity
Nagios XI Remote Code Execution Exploited
- 9.8 Critical severity
Webmin Command Injection Exploited
- 8.8 High severity
- 9.8 Critical severity
- 9.8 Critical severity
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