CVE-2021-45621

Certain NETGEAR devices are affected by command injection by an unauthenticated attacker. This affects CBR40 before 2.5.0.24, CBR750 before 3.2.18.2, EAX20 before 1.0.0.58, EAX80 before 1.0.1.68, EX3700 before 1.0.0.94, EX3800 before 1.0.0.94, EX6120 before 1.0.0.64, EX6130 before 1.0.0.44, EX7000 before 1.0.1.104, EX7500 before 1.0.0.74, LAX20 before 1.1.6.28, MR60 before 1.0.6.116, MS60 before 1.0.6.116, R6300v2 before 1.0.4.52, R6400 before 1.0.1.70, R6400v2 before 1.0.4.106, R6700v3 before 1.0.4.106, R6900P before 1.3.3.140, R7000 before 1.0.11.126, R7000P before 1.3.3.140, R7100LG before 1.0.0.72, R7850 before 1.0.5.74, R7900 before 1.0.4.46, R7900P before 1.4.2.84, R7960P before 1.4.2.84, R8000 before 1.0.4.74, R8000P before 1.4.2.84, R8300 before 1.0.2.154, R8500 before 1.0.2.154, RAX15 before 1.0.3.96, RAX20 before 1.0.3.96, RAX200 before 1.0.4.120, RAX35v2 before 1.0.3.96, RAX40v2 before 1.0.3.96, RAX43 before 1.0.3.96, RAX45 before 1.0.3.96, RAX50 before 1.0.3.96, RAX75 before 1.0.4.120, RAX80 before 1.0.4.120, RBK752 before 3.2.17.12, RBK852 before 3.2.17.12, RBK852 before 3.2.17.12, RBR750 before 3.2.17.12, RBR850 before 3.2.17.12, RBR850 before 3.2.17.12, RBS750 before 3.2.17.12, RBS850 before 3.2.17.12, RBS850 before 3.2.17.12, RS400 before 1.5.1.80, XR1000 before 1.0.0.58, and XR300 before 1.0.3.68.

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/000064523/Security-Advisory-for-Pre-Authentication-Command-Injection-on-Some-Routers-Extenders-and-WiFi-Systems-PSV-2020-0562