Research firm Forescout Technologies has identified security issue that affects Microchip MPLAB Harmony Net stack v3.6.1 (FSCT-2020-0043)
High-Level Description
The code that generates Initial Sequence Numbers (ISNs) for TCP connections in Microchip MPLAB Net derives the ISN from an insufficiently random source. As a result, an attacker may be able to determine the ISN of current and future TCP connections and either hijack existing ones or spoof future ones. While the Microchip MPLAB Net ISN generator seems to adhere to RFC 793 (where a global 32-bit counter is incremented roughly every 4 microseconds), proper ISN generation should aim to follow at least the specifications outlined in RFC 6528.
Resolution
Microchip has released MPLAB Harmony Net stack v3.6.4 dot release with the fix, where the calculation of the Initial Sequence Number (ISN) has been updated to include a strong random key.
Microchip MPLAB Harmony Net development team would like to thank Forescout Technologies and its team of researches for helping identify this issue.
Research firm Forescout Technologies has identified security issue that affects Microchip MPLAB Harmony Net stack v3.6.1 (FSCT-2020-0043)
High-Level Description
The code that generates Initial Sequence Numbers (ISNs) for TCP connections in Microchip MPLAB Net derives the ISN from an insufficiently random source. As a result, an attacker may be able to determine the ISN of current and future TCP connections and either hijack existing ones or spoof future ones. While the Microchip MPLAB Net ISN generator seems to adhere to RFC 793 (where a global 32-bit counter is incremented roughly every 4 microseconds), proper ISN generation should aim to follow at least the specifications outlined in RFC 6528.
Resolution
Microchip has released MPLAB Harmony Net stack v3.6.4 dot release with the fix, where the calculation of the Initial Sequence Number (ISN) has been updated to include a strong random key.
Microchip MPLAB Harmony Net development team would like to thank Forescout Technologies and its team of researches for helping identify this issue.