CVE-2021-20613

Improper initialization vulnerability in MELSEC-F series FX3U-ENET Firmware version 1.16 and prior, FX3U-ENET-L Firmware version 1.16 and prior and FX3U-ENET-P502 Firmware version 1.16 and prior allows a remote unauthenticated attacker to cause a denial-of-service (DoS) condition in communication function of the product by sending specially crafted packets. Control by MELSEC-F series PLC is not affected by this vulnerability, but system reset is required for recovery.

Weakness

The product does not initialize or incorrectly initializes a resource, which might leave the resource in an unexpected state when it is accessed or used.

Affected Software

Potential Mitigations

• Use a language that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid.
• For example, in Java, if the programmer does not explicitly initialize a variable, then the code could produce a compile-time error (if the variable is local) or automatically initialize the variable to the default value for the variable’s type. In Perl, if explicit initialization is not performed, then a default value of undef is assigned, which is interpreted as 0, false, or an equivalent value depending on the context in which the variable is accessed.

Related Attack Patterns

• https://cwe.mitre.org/data/definitions/26.html
• https://cwe.mitre.org/data/definitions/29.html

References

• https://jvn.jp/vu/JVNVU93268332/index.html
• https://www.cisa.gov/uscert/ics/advisories/icsa-22-013-07
• https://www.mitsubishielectric.com/en/psirt/vulnerability/pdf/2021-024_en.pdf