CVE-2021-45550

Certain NETGEAR devices are affected by command injection by an authenticated user. This affects D3600 before 1.0.0.76, D6000 before 1.0.0.78, D6100 before 1.0.0.63, D6220 before 1.0.0.52, D6400 before 1.0.0.86, D7800 before 1.0.1.56, D8500 before 1.0.3.44, DGN2200Bv4 before 1.0.0.109, DGN2200v4 before 1.0.0.110, R6250 before 1.0.4.34, R6300v2 before 1.0.4.34, R6400 before 1.0.1.46, R6400v2 before 1.0.2.66, R6700 before 1.0.2.6, R6700v3 before 1.0.2.66, R6900 before 1.0.2.4, R6900P before 1.3.1.64, R7000 before 1.0.9.42, R7000P before 1.3.1.64, R7100LG before 1.0.0.50, R7300 before 1.0.0.70, R7900 before 1.0.3.8, R7900P before 1.4.1.30, R8000 before 1.0.4.28, R8000P before 1.4.1.30, R8300 before 1.0.2.128, R8500 before 1.0.2.128, WNDR3400v3 before 1.0.1.24, WNR3500Lv2 before 1.2.0.62, and XR500 before 2.3.2.56.

Weakness

The product constructs all or part of a command using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify the intended command when it is sent to a downstream component.

Affected Software

Extended Description

Command injection vulnerabilities typically occur when:

Many protocols and products have their own custom command language. While OS or shell command strings are frequently discovered and targeted, developers may not realize that these other command languages might also be vulnerable to attacks. Command injection is a common problem with wrapper programs.

Potential Mitigations

• Assume all input is malicious. Use an “accept known good” input validation strategy, i.e., use a list of acceptable inputs that strictly conform to specifications. Reject any input that does not strictly conform to specifications, or transform it into something that does.
• When performing input validation, consider all potentially relevant properties, including length, type of input, the full range of acceptable values, missing or extra inputs, syntax, consistency across related fields, and conformance to business rules. As an example of business rule logic, “boat” may be syntactically valid because it only contains alphanumeric characters, but it is not valid if the input is only expected to contain colors such as “red” or “blue.”
• Do not rely exclusively on looking for malicious or malformed inputs. This is likely to miss at least one undesirable input, especially if the code’s environment changes. This can give attackers enough room to bypass the intended validation. However, denylists can be useful for detecting potential attacks or determining which inputs are so malformed that they should be rejected outright.

Related Attack Patterns

• https://cwe.mitre.org/data/definitions/136.html
• https://cwe.mitre.org/data/definitions/15.html
• https://cwe.mitre.org/data/definitions/183.html
• https://cwe.mitre.org/data/definitions/248.html
• https://cwe.mitre.org/data/definitions/40.html
• https://cwe.mitre.org/data/definitions/43.html
• https://cwe.mitre.org/data/definitions/75.html
• https://cwe.mitre.org/data/definitions/76.html

References

• https://kb.netgear.com/000064049/Security-Advisory-for-Post-Authentication-Command-Injection-on-Some-Routers-PSV-2018-0376