Snort mailing list archives

Re: [Emerging-Sigs] Offered new rule for detect last Outlook/Crypto API...


From: Will Metcalf <wmetcalf () emergingthreatspro com>
Date: Tue, 12 Nov 2013 17:14:06 -0600

Thanks will get this into QA.


On Tue, Nov 12, 2013 at 5:49 PM, rmkml <rmkml () yahoo fr> wrote:

Hi,

ok first, I have developped this rule during my new project:
http://etplc.org

Thx Nruns company for recently released an old design bug in Microsoft
Outlook/Crypto API X.509:

http://blog.nruns.com/blog/2013/11/12/A-portscan-by-email-Alex/
http://seclists.org/fulldisclosure/2013/Nov/84

Please found a "specific" rule release for detecting this:

alert tcp $EXTERNAL_NET any -> $SMTP_SERVERS $SMTP_PORTS (msg:"SMTP
SPECIFIC Microsoft Outlook/Crypto API X.509 design bug allow blind HTTP
requests attempt";
flow:to_server,established; content:"multipart/signed|3B|"; nocase;
content:"application/pkcs7-signature|3B|"; nocase; distance:0;
content:"|0A|QUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFB|0D|";
distance:0;
reference:cve,2013-3870; reference:url,www.microsoft.
com/technet/security/bulletin/MS13-068.mspx; reference:url,blog.nruns.com/
blog/2013/11/12/A-portscan-by-email-Alex; classtype:attempted-admin;
sid:95420; rev:1;)

Maybe this rule or others will be improved in future (using file_data for
decoding base64, checking x509 certificate 1.1.1.1..., checking UA
CryptoAPI outgoing proxy...).

Don't remember checking snort variables like $SMTP_SERVERS...

All comments are welcome.

Regards
@Rmkml
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