Intel (Skylake / Kaby Lake) PortSmash CPU SMT Side-Channel

2018.11.05
Credit: Billy Brumley
Risk: Medium
Local: Yes
Remote: No
CWE: N/A

# Summary This is a proof-of-concept exploit of the PortSmash microarchitecture attack, tracked by CVE-2018-5407. ![Alt text](parse_raw_simple.png?raw=true "Title") # Setup ## Prerequisites A CPU featuring SMT (e.g. Hyper-Threading) is the only requirement. This exploit code should work out of the box on Skylake and Kaby Lake. For other SMT architectures, customizing the strategies and/or waiting times in `spy` is likely needed. ## OpenSSL Download and install OpenSSL 1.1.0h or lower: cd /usr/local/src wget https://www.openssl.org/source/openssl-1.1.0h.tar.gz tar xzf openssl-1.1.0h.tar.gz cd openssl-1.1.0h/ export OPENSSL_ROOT_DIR=/usr/local/ssl ./config -d shared --prefix=$OPENSSL_ROOT_DIR --openssldir=$OPENSSL_ROOT_DIR -Wl,-rpath=$OPENSSL_ROOT_DIR/lib make -j8 make test sudo checkinstall --strip=no --stripso=no --pkgname=openssl-1.1.0h-debug --provides=openssl-1.1.0h-debug --default make install_sw If you use a different path, you'll need to make changes to `Makefile` and `sync.sh`. # Tooling ## freq.sh Turns off frequency scaling and TurboBoost. ## sync.sh Sync trace through pipes. It has two victims, one of which should be active at a time: 1. The stock `openssl` running `dgst` command to produce a P-384 signature. 2. A harness `ecc` that calls scalar multiplication directly with a known key. (Useful for profiling.) The script will generate a P-384 key pair in `secp384r1.pem` if it does not already exist. The script outputs `data.bin` which is what `openssl dgst` signed, and you should be able to verify the ECDSA signature `data.sig` afterwards with openssl dgst -sha512 -verify secp384r1.pem -signature data.sig data.bin In the `ecc` tool case, `data.bin` and `secp384r1.pem` are meaningless and `data.sig` is not created. For the `taskset` commands in `sync.sh`, the cores need to be two logical cores of the same physical core; sanity check with $ grep '^core id' /proc/cpuinfo core id : 0 core id : 1 core id : 2 core id : 3 core id : 0 core id : 1 core id : 2 core id : 3 So the script is currently configured for logical cores 3 and 7 that both map to physical core 3 (`core_id`). ## spy Measurement process that outputs measurements in `timings.bin`. To change the `spy` strategy, check the port defines in `spy.h`. Only one strategy should be active at build time. Note that `timings.bin` is actually raw clock cycle counter values, not latencies. Look in `parse_raw_simple.py` to understand the data format if necessary. ## ecc Victim harness for running OpenSSL scalar multiplication with known inputs. Example: ./ecc M 4 deadbeef0123456789abcdef00000000c0ff33 Will execute 4 consecutive calls to `EC_POINT_mul` with the given hex scalar. ## parse_raw_simple.py Quick and dirty hack to view 1D traces. The top plot is the raw trace. Everything below is a different digital filter of the raw trace for viewing purposes. Zoom and pan are your friends here. You might have to adjust the `CEIL` variable if the plots are too aggressively clipped. Python packages: sudo apt-get install python-numpy python-matplotlib # Usage Turn off frequency scaling: ./freq.sh Make sure everything builds: make clean make Take a measurement: ./sync.sh View the trace: python parse_raw_simple.py timings.bin You can play around with one victim at a time in `sync.sh`. Sample output for the `openssl dgst` victim is in `parse_raw_simple.png`. # Credits * Alejandro Cabrera Aldaya (Universidad Tecnológica de la Habana (CUJAE), Habana, Cuba) * Billy Bob Brumley (Tampere University of Technology, Tampere, Finland) * Sohaib ul Hassan (Tampere University of Technology, Tampere, Finland) * Cesar Pereida García (Tampere University of Technology, Tampere, Finland) * Nicola Tuveri (Tampere University of Technology, Tampere, Finland) EDB Download: https://github.com/offensive-security/exploitdb-bin-sploits/raw/master/bin-sploits/45785.zip


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