Fix bug that leads to ~23.3% miss rate on kernel32.dll (among others) #71
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cyb3rjerry
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just going to double check the original sample first 277d7f450268aeb4e7fe942f70a9df63aa429d703e9400370f0621a438e918bf |
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I can give it a run and post the results here if it can help 👀 |
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Hey folks, after working on a Lumma v3 sample I realized the current Murmur2 implementation was giving the wrong hash roughly 23.4% of the time. After a bit of investigation,
72Ghoulon the OALab discord server figured out hashdb's current implementation gives the wrong hash when there is one byte remaining after processing the 4 byte chunks.You can find a diff of kernel32 with the old and new algo (respectively) here: https://www.diffchecker.com/V717U9Cf/
The new implementation is based off https://github.com/Orochimarufan/cdev/blob/master/cdev/murmurhash2.py and has a 0% miss rate. I tested it locally on kernel32.dll, sqlite3.dll and wininet.dll.