NIS/NAV has the ability to detect unknown viruses of various types using heuristic algorithms
known as Bloodhound Technology
. According to Symantec, files that are detected
are a heuristic detection for the Windows Media Player ASF Invalid Codec Entries Count Vulnerability (as described in Microsoft Security Bulletin MS06-078
). Under the Technical Details tab, Symantec indicates files that are detected as Bloodhound.Exploit.101 may
or may not
be malicious. Symantec asks that you Submit Virus Samples
detected as this threat to the Symantec Security Response Team.
Symantec's technology uses an expert system to analyze the cataloged behaviors and assess the likelihood of viral infection. Bloodhound is not the name of a virus, but a message displayed by NAV when it thinks it may have found a new virus
which is categorized as Exploit, Packed variants in their defintion files
. Heuristic analysis
is the ability of an anti-virus program to detect possible new variants of malware
before the vendor can get samples and update the program's definitions for detection. Heuristics uses non-specific detection methods to find new or unknown malware which allows the anti-virus to detect and stop if before doing any harm to your system. Heuristic scanning methods vary depending on the vendor. Some claim to allow emulation of the file's activities in a virtual sandbox. Others scan the file more intensively, searching line by line inspecting the code in a file to see if it contains virus-like characteristics. If the number of these characteristics/instructions exceeds a pre-defined threshold, the file is flagged as a possible virus
to using heuristics is that it is not as reliable as signature-based detection (blacklisting) and can potentially increase the chances that a non-malicious program is flagged as malicious. With heuristics, there is always a potential risk
for a "False Positive
" if virus detection technology (AutoProtect Settings) are set to High for Bloodhound and the heuristic analysis flags a file as suspicious
that contains no malware. You may want to Reset Bloodhound to default settings
and try scanning again.
NAV is doing its job when alerting to a Bloodhound exploit but from personal experience and testing, I have found some of these alerts to be a false positive. You need to investigate further and follow Symantec's instructions for submitting samples.