The Compression Sweep feature in WebRoot Spy Sweeper 4.5.9 and earlier does not handle non-ZIP archives, which allows remote attackers to bypass the malware detection via files with (1) RAR, (2) GZ, (3) TAR, (4) CAB, or (5) ACE compression.
WebRoot Spy Sweeper 4.5.9 and earlier does not detect malware based on file contents, which allows remote attackers to bypass malware detection by changing a file's name.