Re: Snort-sigs Digest, Vol 12, Issue 50

[Ashlee Benge <abenge () sourcefire com>]

Yaser,

      We have reviewed the rules you submitted for CVE-2017-8570.
Unfortunately, due to the obfuscation method used in the samples and a lack
of static content matches, performance concerns prevent us from adding
these rules to the ruleset.

On Tue, May 29, 2018 at 1:24 PM, <snort-sigs-request () lists snort org> wrote:

> Send Snort-sigs mailing list submissions to
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> Today's Topics:
>
>    1. Win.Trojan.Dropper (O C)
>    2. CVE-2017-8570 (O C)
>
>
> ----------------------------------------------------------------------
>
> Message: 1
> Date: Tue, 29 May 2018 17:23:40 +0000
> From: O C <snort () outlook com>
> To: snort-sigs <snort-sigs () lists snort org>
> Subject: [Snort-sigs] Win.Trojan.Dropper
> Message-ID:
>         <BN6PR1701MB18437AD38F6A61C998EECA4AA86D0@BN6PR1701MB1843.
> namprd17.prod.outlook.com>
>
> Content-Type: text/plain; charset="iso-8859-1"
>
> Hi,
>
> This downloader uses a rather unique User-Agent. Pcap is available for
> this one.
>
> # --------------------
> # Date: 2018-05-28
> # Title: Win.Trojan.Dropper
> # Tests: pcap
> # Reference: https://www.virustotal.com/#/file/
> 782cc4188618cf0c4815f85ea7873a004464095f5ed459b8d1579fa27ce5810e/detection
>
> alert tcp $HOME_NET any -> $EXTERNAL_NET $HTTP_PORTS (msg:"MALWARE-CNC
> known malicious user-agent - Win.Trojan.Dropper";
> flow:to_server,established; content:"User-Agent: HTTPREAD|0D 0A|";
> fast_pattern:only; metadata:ruleset community, service http; reference:url,
> www.virustotal.com/#/file/782cc4188618cf0c4815f85ea7873a
> 004464095f5ed459b8d1579fa27ce5810e/detection; classtype:trojan-activity;
> sid:8000074; rev:1;)
>
> Thanks.
> YM
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> ------------------------------
>
> Message: 2
> Date: Tue, 29 May 2018 17:24:12 +0000
> From: O C <snort () outlook com>
> To: snort-sigs <snort-sigs () lists snort org>
> Subject: [Snort-sigs] CVE-2017-8570
> Message-ID:
>         <BN6PR1701MB184314ADF9539049956466D5A86D0@BN6PR1701MB1843.
> namprd17.prod.outlook.com>
>
> Content-Type: text/plain; charset="iso-8859-1"
>
> Hi,
>
> This one is similar to the existing signatures 45415 and 45416. The only
> difference is that is uses the StdOleLink Moniker as opposed to the
> Composite Moiker. There are 2 versions for each rule. The first one is
> without using PCRE. The samples I worked with had the moniker slightly
> manipulated, and PCRE was a perfect fit. Pcaps available for these.
>
> Note that the sample documents contain multiple exploits and not just one.
>
> # --------------------
> # Date: 2018-05-06
> # Title: CVE-2017-8570 StdOleLink
> # Reference: https://www.virustotal.com/#/file/
> bebd4cd9aece49fbe6e7024e239638004358ff87d02f9bd4328993409da9e17c/detection,
> https://www.virustotal.com/#/file/af9ed7de1d9d9d38ee12ea2d3c62ab
> 01a79c6f4b241c02110bac8a53ea9798b5/detection
> # Tests: pcap
>
> alert tcp $EXTERNAL_NET $FILE_DATA_PORTS -> $HOME_NET any
> (msg:"FILE-OFFICE RTF StdOleLink Moniker object creation attempt -
> NON-PCRE"; flow:to_client,established; flowbits:isset,file.rtf; file_data;
> content:"|5C|objupdate"; content:"003000000000000C000000000000046";
> distance:0; fast_pattern; nocase; content:"C6AFABEC197FD211978E0000F8757E2A";
> distance:0; nocase; metadata:ruleset community, service ftp-data, service
> http, service imap, service pop3; reference:cve,2017-8570; reference:url,
> portal.msrc.microsoft.com/en-us/security-guidance/advisory/CVE-2017-8570;
> reference:url,www.virustotal.com/#/file/bebd4cd9aece49fbe6e7024e239638
> 004358ff87d02f9bd4328993409da9e17c/detection; reference:url,
> www.virustotal.com/#/file/af9ed7de1d9d9d38ee12ea2d3c62ab
> 01a79c6f4b241c02110bac8a53ea9798b5/detection; classtype:attempted-user;
> sid:8000070; rev:1;)
>
> alert tcp $EXTERNAL_NET $FILE_DATA_PORTS -> $HOME_NET any
> (msg:"FILE-OFFICE RTF StdOleLink Moniker object creation attempt - PCRE";
> flow:to_client,established; flowbits:isset,file.rtf; file_data;
> content:"|5C|objupdate"; content:"003000000000000C000000000000046";
> distance:0; fast_pattern; nocase; pcre:"/[ABCDEF0-9\x20\x0a\x0d0a]{32}/";
> distance:0; nocase; metadata:ruleset community, service ftp-data, service
> http, service imap, service pop3; reference:cve,2017-8570; reference:url,
> portal.msrc.microsoft.com/en-us/security-guidance/advisory/CVE-2017-8570;
> reference:url,www.virustotal.com/#/file/bebd4cd9aece49fbe6e7024e239638
> 004358ff87d02f9bd4328993409da9e17c/detection; reference:url,
> www.virustotal.com/#/file/af9ed7de1d9d9d38ee12ea2d3c62ab
> 01a79c6f4b241c02110bac8a53ea9798b5/detection; classtype:attempted-user;
> sid:8000071; rev:1;)
>
> alert tcp $EXTERNAL_NET any -> $SMTP_SERVERS 25 (msg:"FILE-OFFICE RTF
> StdOleLink Moniker object creation attempt - NON-PCRE";
> flow:to_server,established; flowbits:isset,file.rtf; file_data;
> content:"|5C|objupdate"; content:"003000000000000C000000000000046";
> distance:0; fast_pattern; nocase; content:"C6AFABEC197FD211978E0000F8757E2A";
> distance:0; nocase; metadata:ruleset community, service ftp-data, service
> http, service imap, service pop3; reference:cve,2017-8570; reference:url,
> portal.msrc.microsoft.com/en-us/security-guidance/advisory/CVE-2017-8570;
> reference:url,www.virustotal.com/#/file/bebd4cd9aece49fbe6e7024e239638
> 004358ff87d02f9bd4328993409da9e17c/detection; reference:url,
> www.virustotal.com/#/file/af9ed7de1d9d9d38ee12ea2d3c62ab
> 01a79c6f4b241c02110bac8a53ea9798b5/detection; classtype:attempted-user;
> sid:8000072; rev:1;)
>
> alert tcp $EXTERNAL_NET any -> $SMTP_SERVERS 25 (msg:"FILE-OFFICE RTF
> StdOleLink Moniker object creation attempt - PCRE";
> flow:to_server,established; flowbits:isset,file.rtf; file_data;
> content:"|5C|objupdate"; content:"003000000000000C000000000000046";
> distance:0; fast_pattern; nocase; pcre:"/[ABCDEF0-9\x20\x0a\x0d0a]{32}/";
> distance:0; nocase; metadata:ruleset community, service ftp-data, service
> http, service imap, service pop3; reference:cve,2017-8570; reference:url,
> portal.msrc.microsoft.com/en-us/security-guidance/advisory/CVE-2017-8570;
> reference:url,www.virustotal.com/#/file/bebd4cd9aece49fbe6e7024e239638
> 004358ff87d02f9bd4328993409da9e17c/detection; reference:url,
> www.virustotal.com/#/file/af9ed7de1d9d9d38ee12ea2d3c62ab
> 01a79c6f4b241c02110bac8a53ea9798b5/detection; classtype:attempted-user;
> sid:8000073; rev:1;)
>
> Thanks.
> YM
>
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> ------------------------------
>
> End of Snort-sigs Digest, Vol 12, Issue 50
> ******************************************



-- 
Ashlee Benge
Detection Response Team
Talos Group

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