> How many sgx side channel attacks are there

As of my last update in September 2021, there have been multiple side-channel attacks targeting Intel's Software Guard Extensions (SGX). Some of the prominent ones include:

1. **Foreshadow (also known as L1 Terminal Fault)**: Targets the L1 data cache of Intel CPUs.

2. **SpectreSGX**: Exploits speculative execution to extract information from SGX enclaves.

3. **Plundervolt**: Manipulates CPU voltage to induce faults inside SGX enclaves and then exploit these faults.

4. **SGAxe**: Exploits the CacheOut attack technique to leak enclave secrets.

5. **LVI (Load Value Injection)**: Combines Meltdown-type data leakage with data-oriented attacks.

Other related vulnerabilities and transient execution attacks (like Meltdown, Spectre, RIDL, Fallout, ZombieLoad, etc.) can potentially impact SGX's security indirectly. Research in this area is active, and newer side-channel attacks or variations might emerge. It's advisable to check the latest literature or Intel's security advisories for up-to-date information.