[Snort-sigs] CVE-2018-8162 rule

Sevens Benoît Benoit.Sevens at mil.be
Thu Jun 7 08:10:14 EDT 2018


Hi all,

Our IDS has triggered on the HTTP download of an xls file with sha256: 714b5fba91302b5a6acfc4d659329dbde429f1fa4460970d60e76711da67b94a

The file can be downloaded from Virustotal

The rule that triggered was this one: 

alert tcp $EXTERNAL_NET $FILE_DATA_PORTS -> $HOME_NET any (msg:"FILE-OFFICE Microsoft Office Excel BOF memory disclosure attempt"; flow:to_client,established; flowbits:isset, file.xls; file_data; content:"|09 08 10 00 00 06 05 00|"; content:"|07|"; within:1; distance:3; byte_test:1,&,16, 0, relative; byte_test:1,&,1, 0, relative; byte_test:1,&,8, 0, relative; metadata:policy balanced-ips drop, policy max-detect-ips drop, policy security-ips drop, service ftp-data, service http, service imap, service pop3; reference:cve,2016-0140; reference:cve,2018-8162; reference:url,portal.msrc.microsoft.com/en-us/security-guidance/advisory/CVE-2018-8162; reference:url,technet.microsoft.com/en-us/security/bulletin/ms16-054; classtype:attempted-recon; sid:38785; rev:4;)

It is hard for us to say now if this is a false positive or not, taking into account the fact that exploits for these CVE's could not be found online.

Does anyone have more knowledge on this Snort signature in order to determine if this is a false positive or not?

Regards,

Benoit
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