CVE-2019-20732

Certain NETGEAR devices are affected by command injection by an authenticated user. This affects D6220 before 1.0.0.40, D7000v2 before 1.0.0.74, D8500 before 1.0.3.39, DGN2200v4 before 1.0.0.102, DGND2200Bv4 before 1.0.0.102, EX3700 before 1.0.0.70, EX3800 before 1.0.0.70, EX6000 before 1.0.0.30, EX6100 before 1.0.2.22, EX6120 before 1.0.0.40, EX6130 before 1.0.0.22, EX6150v1 before 1.0.0.42, EX6200 before 1.0.3.88, EX7000 before 1.0.0.66, R6250 before 1.0.4.20, R6300v2 before 1.0.4.24, R6400 before 1.0.1.32, R6400v2 before 1.0.2.44, R6700 before 1.0.1.46, R6900 before 1.0.1.46, R7000 before 1.0.9.26, R6900P before 1.3.0.20, R7000P before 1.3.0.20, R7100LG before 1.0.0.40, R7300DST before 1.0.0.62, R7900 before 1.0.2.10, R8000 before 1.0.4.12, R7900P before 1.3.0.10, R8000P before 1.3.0.10, R8300 before 1.0.2.106, R8500 before 1.0.2.106, WN2500RPv2 before 1.0.1.54, WNDR3400v3 before 1.0.1.18, and WNR3500Lv2 before 1.2.0.48.

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/000061195/Security-Advisory-for-Post-Authentication-Command-Injection-on-Some-Routers-Gateways-and-Extenders-PSV-2017-2228