CLSID in filenames

Peter Bonivart bonivart at opencsw.org
Thu Mar 8 12:48:48 GMT 2012


I have some customers receiving files like this:
VENDET_83410_20120124_{396E4021-9322-4F70-9A2C-45ECD782B8A6}.pdf.

They trigger the default CLSID rule in filename.rules.conf:

# Deny filenames containing CLSID's
deny	\{[a-hA-H0-9-]{25,}\}	Filename trying to hide its real
type				Files containing CLSID's are trying to hide their real type

I googled it and found this:
http://www.juniper.net/security/auto/vulnerabilities/vuln2612.html.
According to that it's only dangerous if the CLSID is at the end of
the filename, in the example above a normal extension comes after the
CLSID. Would it be recommended to change the rule to something like
this?

# Deny filenames containing CLSID's
deny	\{[a-hA-H0-9-]{25,}\}$	Filename trying to hide its real
type				Files containing CLSID's are trying to hide their real type

/peter


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