The attached file crashes in CmdExtract::UnstoreFile because the signed int64 DestUnpSize is truncated to an unsigned 32bit integer. Perhaps CmdExtract::ExtractCurrentFile should sanity check Arc.FileHead.UnpSize early. The researcher observed this crash in Avast Antivirus, but the origin of the code appears to be the unrar source distribution. Many other antiviruses may be affected, and presumably WinRAR and other archivers.