Aro.dat is, in fact, an encrypted and compressed PlugX payload. The decryption routine within Aro.dat closely resembles that of older PlugX variants (see Figure 3 below) in that it involves multiple decryption keys and bit shift operations. Once decrypted, it gets decompressed via the Windows API RtlDecompressBuffer into a Windows module (DLL). The compression algorithm is LZ compression (COMPRESSION_FORMAT_LZNT1).