Re: How to detect current images-only messages?
On 6/21/06, Matt <[EMAIL PROTECTED]> wrote: Ditto... having the same problem. Here are the headers from one.. it got only a 2.0! Is there somethign I can do to just block any inline images? C{UT} Received: from ntmail2.shscares.org (10.193.16.28 [10.193.16.28]) by ntmail1.shscares.org with SMTP (Microsoft Exchange Internet Mail Service Version 5.5.2653.13) id L4MRBC9T; Wed, 14 Jun 2006 07:55:40 -0400 Received: (qmail 14909 invoked by uid 508); 14 Jun 2006 13:03:49 - Received: from [EMAIL PROTECTED] by ntmail2.shscares.org by uid 502 with SpamCobra Virus And Spam Protection (spamassassin: 2.64. Clear:RC:0(88.241.210.218):SA:0(2.1/5.0):. Processed in 5.118316 secs); 14 Jun 2006 13:03:49 - X-Spam-Status: No, hits=2.1 required=5.0 X-Spam-Level: ++ Received: from unknown (HELO enaiyy) (88.241.210.218) by 0 with SMTP; 14 Jun 2006 13:03:44 - Received: from hj.eg ([88.241.218.148]) by enaiyy (8.13.5/8.13.5) with SMTP id k5EC0ao8072049; Wed, 14 Jun 2006 15:00:36 +0300 Message-ID: <[EMAIL PROTECTED]> From: "Julius Clayton" <[EMAIL PROTECTED]> To: <[EMAIL PROTECTED]> Subject: debut dormitory Date: Wed, 14 Jun 2006 14:50:04 +0300 MIME-Version: 1.0 Content-Type: multipart/related; type="multipart/alternative"; boundary="=_NextPart_000_0021_01C68FC2.A03F56FA" X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2900.2180 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.2180 X-Spam-Checker-Version: SpamAssassin 2.64 (2004-01-11) on ntmail2.shscares.org X-Spam-Status: No, hits=2.1 required=5.0 tests=CHILI_IMG_ONLY,HTML_70_80, HTML_IMAGE_ONLY_12,HTML_MESSAGE autolearn=no version=2.64 X-Spam-Pyzor: Reported 0 times. On 6/21/06, Yves Goergen <[EMAIL PROTECTED]> wrote: > On 21.06.2006 03:22 CE(S)T, jdow wrote: > > SARE and SpamAssassin > > plus the BLs have not let a ONE of either of those through yet this > > year. > > Can you please explain me, what exact rules you added from SARE? I > cannot find anything usable there. > > -- > Yves Goergen "LonelyPixel" <[EMAIL PROTECTED]> > http://beta.unclassified.de – My web laboratory. >
Re: How to detect current images-only messages?
On 21.06.2006 03:22 CE(S)T, jdow wrote: > SARE and SpamAssassin > plus the BLs have not let a ONE of either of those through yet this > year. Can you please explain me, what exact rules you added from SARE? I cannot find anything usable there. -- Yves Goergen "LonelyPixel" <[EMAIL PROTECTED]> http://beta.unclassified.de – My web laboratory.
Re: How to detect current images-only messages?
I am imagining the amount of processor resource scanning 100,000 messages per day let alone the tens of millions or more that some sites see. I think Google could do it with their machine. It's not needed, either. VERY few get through in practice. All ya need is SpamAssassin and SARE. Then Bob's your uncle. (I figured "checksum" right off. Thirty millisecond later I figured the random pixels - one is enough per image - counter. And maybe 60 milliseconds later I realized that the image is just a large captcha and that the captcha problem has been "solved", although it takes a lot of computational resource. About a day later a lower usage solution presented itself - take blocks of data from the image and look at their average color. For an optimal size and number of such blocks you can create a fairly reliable signature. Ba-da-bing. Then multiple images appeared. Of course, during the whole flight of thought I kept in mind the question, "But WHY?" SARE and SpamAssassin plus the BLs have not let a ONE of either of those through yet this year.) {^_^} - Original Message - From: "Thomas Raef" <[EMAIL PROTECTED]> This thread might be dead, but I just read this and thought it might provide some insight, or thought, or something: Network World's Messaging Newsletter, 06/20/06 How IronPort tackles image-based spam By Michael Osterman Following my discussion with Vircom about the problems the e-mail security firm is finding with image-based spam (as reported in last week's newsletter), I spoke with IronPort about the issue. IronPort is finding that about 12% of all spam is currently image-based, but that only a small handful of spammers are currently using it. However, because of the inability of many spam filters to adequately detect and stop this type of spam, the capture rate is much lower than for conventional spam. The result is that upwards of 50% of the spam received by end users is image-based spam. Conventional anti-spam systems using heuristics are quite poor at stopping image spam. Signature-based approaches are also inadequate because randomization techniques easily bypass these signatures. Randomization can take the form of inserting random pixels in a GIF image, which are imperceptible to viewers but that can easily break traditional binary signatures, or by changing palette or border colors. While randomization capabilities for image-based spam are not yet built into spam tool kits available on the Web, it's probably only a matter of time before this is the case. IronPort's approach is to use what it calls Context Adaptive Scanning - basically, profiling image spam to look for patterns across the message, the reputation of the sender, whether or not a dynamic IP address is used, how the message is constructed and other information. IronPort's approach also looks for color patterns within an image that can identify the presence of text within an image, since the vast majority of valid images sent through e-mail rarely contain a substantial quantity of text. Using these techniques, IronPort is currently able to stop about 98% of image-based with a very low false positive ratio. How much of a problem is image-based spam for your organization? Are you finding an increase in this type of spam and are you having difficulty detecting and stopping it?
RE: How to detect current images-only messages?
Title: Re: How to detect current images-only messages? This thread might be dead, but I just read this and thought it might provide some insight, or thought, or something: Network World's Messaging Newsletter, 06/20/06 How IronPort tackles image-based spam By Michael Osterman Following my discussion with Vircom about the problems the e-mail security firm is finding with image-based spam (as reported in last week's newsletter), I spoke with IronPort about the issue. IronPort is finding that about 12% of all spam is currently image-based, but that only a small handful of spammers are currently using it. However, because of the inability of many spam filters to adequately detect and stop this type of spam, the capture rate is much lower than for conventional spam. The result is that upwards of 50% of the spam received by end users is image-based spam. Conventional anti-spam systems using heuristics are quite poor at stopping image spam. Signature-based approaches are also inadequate because randomization techniques easily bypass these signatures. Randomization can take the form of inserting random pixels in a GIF image, which are imperceptible to viewers but that can easily break traditional binary signatures, or by changing palette or border colors. While randomization capabilities for image-based spam are not yet built into spam tool kits available on the Web, it's probably only a matter of time before this is the case. IronPort's approach is to use what it calls Context Adaptive Scanning - basically, profiling image spam to look for patterns across the message, the reputation of the sender, whether or not a dynamic IP address is used, how the message is constructed and other information. IronPort's approach also looks for color patterns within an image that can identify the presence of text within an image, since the vast majority of valid images sent through e-mail rarely contain a substantial quantity of text. Using these techniques, IronPort is currently able to stop about 98% of image-based with a very low false positive ratio. How much of a problem is image-based spam for your organization? Are you finding an increase in this type of spam and are you having difficulty detecting and stopping it? From: Alan Premselaar [mailto:[EMAIL PROTECTED]Sent: Tue 6/20/2006 12:57 AMTo: jdowCc: users@spamassassin.apache.orgSubject: Re: How to detect current images-only messages? -BEGIN PGP SIGNED MESSAGE-Hash: SHA1jdow wrote:> From: "Chris Santerre" <[EMAIL PROTECTED]>>>> From: Yves Goergen [mailto:[EMAIL PROTECTED]]>>>>>> Hello,>>> I keep receiving messages that contain of nothing but composed images.>>> They're HTML messages with only tags in them. There seems to be a>>> rule that checks if the message has *any* image and compares it to its>>> length. That gave my spam some scores recently but not so today. I>>> received a message that looks just like the others but has no score at>>> all due to the fact that it only contains of images.>>>>>> Is there any way to detect this type of message with SpamAssassin? I>>> cannot think of a regular _expression_ that would do it, and even if I>>> could, SA offered no way to match it reliably. (See the line-by-line>>> problem with 'rawbody' and encoding problems with 'full'.)>>>> I keep hearing this is a problem, but I'm not seeing it on my end.>> Most are>> being caught:> >>>> I'll have to adjust for those 2. :)>> In case he means no score and no SA markup there is still a way this> can happen. If an email comes in during a very tiny window when spamd> is reloading its configuration (-HUP) the email can sneak through.>> {^_^}Of course this can also happen if the message size is greater than theupper size limit set (default 250k) ... being that it's an image only,I'd say it's definitely a possibility. (I've seen that happen on mysystem in the past)Alan-BEGIN PGP SIGNATURE-Version: GnuPG v1.4.1 (Darwin)Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.orgiD8DBQFEl45SE2gsBSKjZHQRAmKdAKCmcutB8fkoZZQCVMDsZSfBHXpwxACffS9X5T96aD/02CijQdHB+uoy54c==XRir-END PGP SIGNATURE-
Re: How to detect current images-only messages?
-BEGIN PGP SIGNED MESSAGE- Hash: SHA1 jdow wrote: > From: "Chris Santerre" <[EMAIL PROTECTED]> >>> From: Yves Goergen [mailto:[EMAIL PROTECTED] >>> >>> Hello, >>> I keep receiving messages that contain of nothing but composed images. >>> They're HTML messages with only tags in them. There seems to be a >>> rule that checks if the message has *any* image and compares it to its >>> length. That gave my spam some scores recently but not so today. I >>> received a message that looks just like the others but has no score at >>> all due to the fact that it only contains of images. >>> >>> Is there any way to detect this type of message with SpamAssassin? I >>> cannot think of a regular expression that would do it, and even if I >>> could, SA offered no way to match it reliably. (See the line-by-line >>> problem with 'rawbody' and encoding problems with 'full'.) >> >> I keep hearing this is a problem, but I'm not seeing it on my end. >> Most are >> being caught: > >> >> I'll have to adjust for those 2. :) > > In case he means no score and no SA markup there is still a way this > can happen. If an email comes in during a very tiny window when spamd > is reloading its configuration (-HUP) the email can sneak through. > > {^_^} Of course this can also happen if the message size is greater than the upper size limit set (default 250k) ... being that it's an image only, I'd say it's definitely a possibility. (I've seen that happen on my system in the past) Alan -BEGIN PGP SIGNATURE- Version: GnuPG v1.4.1 (Darwin) Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org iD8DBQFEl45SE2gsBSKjZHQRAmKdAKCmcutB8fkoZZQCVMDsZSfBHXpwxACffS9X 5T96aD/02CijQdHB+uoy54c= =XRir -END PGP SIGNATURE-
Re: How to detect current images-only messages?
From: "Chris Santerre" <[EMAIL PROTECTED]> From: Yves Goergen [mailto:[EMAIL PROTECTED] Hello, I keep receiving messages that contain of nothing but composed images. They're HTML messages with only tags in them. There seems to be a rule that checks if the message has *any* image and compares it to its length. That gave my spam some scores recently but not so today. I received a message that looks just like the others but has no score at all due to the fact that it only contains of images. Is there any way to detect this type of message with SpamAssassin? I cannot think of a regular expression that would do it, and even if I could, SA offered no way to match it reliably. (See the line-by-line problem with 'rawbody' and encoding problems with 'full'.) I keep hearing this is a problem, but I'm not seeing it on my end. Most are being caught: I'll have to adjust for those 2. :) In case he means no score and no SA markup there is still a way this can happen. If an email comes in during a very tiny window when spamd is reloading its configuration (-HUP) the email can sneak through. {^_^}
RE: How to detect current images-only messages?
Title: RE: How to detect current images-only messages? > -Original Message- > From: Yves Goergen [mailto:[EMAIL PROTECTED]] > Sent: Sunday, June 18, 2006 5:50 AM > To: users@spamassassin.apache.org > Subject: How to detect current images-only messages? > > > Hello, > I keep receiving messages that contain of nothing but composed images. > They're HTML messages with only tags in them. There > seems to be a > rule that checks if the message has *any* image and compares it to its > length. That gave my spam some scores recently but not so today. I > received a message that looks just like the others but has no score at > all due to the fact that it only contains of images. > > Is there any way to detect this type of message with SpamAssassin? I > cannot think of a regular _expression_ that would do it, and even if I > could, SA offered no way to match it reliably. (See the line-by-line > problem with 'rawbody' and encoding problems with 'full'.) I keep hearing this is a problem, but I'm not seeing it on my end. Most are being caught: Some examples X-Spam-Status: Yes, score=7.6 required=5.0 tests=EXTRA_MPART_TYPE,HTML_90_100, HTML_IMAGE_ONLY_08,HTML_MESSAGE,MIME_HTML_MOSTLY,MPART_ALT_DIFF, MY_ALT,MY_DSL,RCVD_IN_NJABL_DUL X-Spam-Status: Yes, score=7.6 required=5.0 tests=HTML_90_100, HTML_IMAGE_ONLY_08,HTML_MESSAGE,MIME_HTML_MOSTLY,MPART_ALT_DIFF, MSGID_DOLLARS,MY_ALT X-Spam-Status: Yes, score=9.2 required=5.0 tests=HTML_90_100, HTML_IMAGE_ONLY_04,HTML_MESSAGE,MIME_HTML_MOSTLY,MPART_ALT_DIFF, MSGID_DOLLARS,MY_ALT,SARE_BOUNDARY_09 X-Spam-Status: Yes, score=8.6 required=5.0 tests=EXTRA_MPART_TYPE, HELO_DYNAMIC_DHCP,HELO_DYNAMIC_IPADDR,HTML_90_100,HTML_IMAGE_ONLY_08, HTML_MESSAGE,MIME_HTML_MOSTLY,MPART_ALT_DIFF,MY_ALT,SPF_HELO_SOFTFAIL X-Spam-Status: Yes, score=5.6 required=5.0 tests=HTML_90_100,HTML_MESSAGE, MIME_HTML_MOSTLY,MPART_ALT_DIFF,MSGID_DOLLARS,MY_ALT Ahhh...occasional slip thru... X-Spam-Status: No, score=4.4 required=5.0 tests=EXTRA_MPART_TYPE,HTML_90_100, HTML_MESSAGE,MIME_HTML_MOSTLY,MPART_ALT_DIFF,MY_ALT,RCVD_IN_NJABL_DUL X-Spam-Status: No, score=4.4 required=5.0 tests=EXTRA_MPART_TYPE, FORGED_RCVD_HELO,HTML_90_100,HTML_IMAGE_ONLY_16,HTML_MESSAGE, MIME_HTML_MOSTLY,MPART_ALT_DIFF,MY_ALT,MY_HELO,SPF_HELO_PASS I'll have to adjust for those 2. :) Chris Santerre SysAdmin and SARE/URIBL ninja http://www.uribl.com http://www.rulesemporium.com