Snort mailing list archives
Re: File preprocessor fails to capture files
From: "Hui Cao (huica)" <huica () cisco com>
Date: Fri, 8 May 2015 12:40:42 +0000
What’s the full snort configuration? If you build snort with debug, you should add:config paf_max: 16384 In addition, it would be better to add: preprocessor normalize_tcp: ips<https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=3&cad=rja&uact=8&ved=0CCQQFjAC&url=http%3A%2F%2Ft73100.security-ids-snort-general.securityupdate.info%2Fpreprocessor-normalize-tcp-ips-t73100.html&ei=B65MVdGDEJObyAT5g4GQBg&usg=AFQjCNEvwb_tSISxggsZbXdfA2SJs7Pm1A&sig2=0_WSEYBph2TfDNTtcatjhw> Best, Hui. From: Pablo Cantos Polaino <pcantos () redborder org<mailto:pcantos () redborder org>> Date: Friday, May 8, 2015 at 8:26 AM To: "snort-users () lists sourceforge net<mailto:snort-users () lists sourceforge net>" <snort-users () lists sourceforge net<mailto:snort-users () lists sourceforge net>> Subject: [Snort-users] File preprocessor fails to capture files Hello all, I'm doing some tests over the file preprocessor and these are the conf options that I'm using related to file preprocessor: include file_magic.conf config file:\ file_type_depth 4294967295, \ file_signature_depth 4294967295, \ file_capture_max 4294967295 preprocessor file_inspect:\ capture_queue_size 50000, \ signature, \ capture_disk /var/log/snort/files/ 50000 This time what I'm trying to do is to capture every file detected by file preprocessor in the directory /var/log/snort/files. For these tests, I've used the following files: wget ftp://ftp.hp.com/pub/information_storage/software/video/video1.avi wget ftp://ftp.hp.com/pub/information_storage/software/video/MakeUp.mov wget ftp://ftp.hp.com/pub/information_storage/software/video/Fighter.mpg wget http://releases.ubuntu.com/14.04/ubuntu-14.04.2-desktop-amd64.iso wget http://scholar.princeton.edu/sites/default/files/oversize_pdf_test_0.pdf wget https://10.0.70.110/client/VMware-viclient.exe --no-check-certificate wget http://cpansearch.perl.org/src/MIKEM/Device-SNP-1.3/datadesigner/tux-sw.bmp I addition, I've got a pcap traffic capture which includes all the 7 files above. When I run Snort reading this pcap, I got the following: Captured files: # ls -lS -rw------- 1 root root 24211979 May 8 11:14 8452B621DC334D1FD44470A80540CBEF2F6869AF851B9E8C684EF9402016F692 -rw------- 1 root root 13045613 May 8 11:14 5CF142947C2957EE648457A91B69FB82F088F31205030F9A77B2AD827228C6E9 -rw------- 1 root root 6352738 May 8 11:14 DB57C532919D9ABABAC127F29DBDC05ED832394880E46CAD81A5DDE713CCB4BE -rw------- 1 root root 2936119 May 8 11:14 B4127F43A3F455523B81179CC11AA4F28FC27F4C041D20E28AA08A32D85CB757 -rw------- 1 root root 495316 May 8 11:14 A294AA3D01CD8902BF842D320E7F2C043AF9EAD95D0E7198C3B71A0DBC9D253C -rw------- 1 root root 424526 May 8 11:14 8863DB1EC4B02D5BCC1FB4BD03D220F7458136342CDD47CE507A5B886C6BB56C -rw------- 1 root root 2817 May 8 11:14 D03CDB1F2584A2C06E866931EC5F31F141D9D08F237E04708C7C19D94FFA62F5 -rw------- 1 root root 1958 May 8 11:14 369FDD6FB34BB5E1F0EC79D063FE0115AEF35AA20972BE8E4739417594F692AA -rw------- 1 root root 1958 May 8 11:14 EF49069F43D349C83873A6784351F16ADC39B8358ACFAE3A30EA4DD684C29DCC -rw------- 1 root root 446 May 8 11:14 8D490C71A27631CF6A476F68C409655CB63BF32C17846A3C3C125A79046DB2C1 Downloaded files: # ls -l -rw-r--r-- 1 root root 2187725 May 8 11:01 Fighter.mpg -rw-r--r-- 1 root root 14955972 May 8 11:01 MakeUp.mov -rw-r--r-- 1 root root 375187792 May 8 11:02 VMware-viclient.exe -rw-r--r-- 1 root root 101688487 Jul 10 2014 oversize_pdf_test_0.pdf -rw-r--r-- 1 root root 446 Mar 22 2013 tux-sw.bmp -rw-r--r-- 1 root root 1044381696 Feb 18 20:12 ubuntu-14.04.2-desktop-amd64.iso -rw-r--r-- 1 root root 6094376 May 8 11:01 video1.avi # sha256sum * 55bdca20aa0ffd8fa3b12029d1e122696a936abc29dd4ec4a5bd878836a5d36f Fighter.mpg 88a43830b006a4ade60874ffb10a0d5afd06245d0bc460da90015ed73df08d58 MakeUp.mov 57bc6123a563056e32fb317c20d1e3b96af723b2b2c9732033e3ab9ce8f8e625 VMware-viclient.exe fa43e683e94372d81210a275cc37112bf2df9c971d377506aab8ae47e5fb0d34 oversize_pdf_test_0.pdf 8d490c71a27631cf6a476f68c409655cb63bf32c17846a3c3c125a79046db2c1 tux-sw.bmp 39eeb28bdb8af630850e75e54b9864ca07640a2bb10bd10055763236b99f9b1d ubuntu-14.04.2-desktop-amd64.iso bb13418aeb4535c0d1f5c491ad69dd87041a8a1ba7dacc6bc763337beaed7dca video1.avi As you can see, Snort just captures correctly the smallest file, that fits in a single packet. The others captured files do not coincide with the captured files (in number and size, and hence in sha256) If I run Snort sniffing from my network interface and I download the 7 files by using the wget command, I got the following: Captured files: -rw------- 1 root root 446 May 8 11:30 8D490C71A27631CF6A476F68C409655CB63BF32C17846A3C3C125A79046DB2C1 This case, Snort just captures the smallest file, that fits in a single packet. I've gone deep into the code and I've found out the problem could come from a strange behavior of the Frag3 preprocessor when dealing with packets that contain files. I see two different issues here: 1.- When sniffing from an interface, Snort is only able to capture files which fit in one single packet. 2.- When reading from a network capture file, Snort is able to capture files in general, but it does it in a wrong way when the file take up more than one packet. I'd like to know if you were aware of these strange behaviors. Best Regards, Pablo Cantos redborder.org<http://redborder.org> / pcantos () redborder org<mailto:pcantos () redborder org>
------------------------------------------------------------------------------ One dashboard for servers and applications across Physical-Virtual-Cloud Widest out-of-the-box monitoring support with 50+ applications Performance metrics, stats and reports that give you Actionable Insights Deep dive visibility with transaction tracing using APM Insight. http://ad.doubleclick.net/ddm/clk/290420510;117567292;y
_______________________________________________ Snort-users mailing list Snort-users () lists sourceforge net Go to this URL to change user options or unsubscribe: https://lists.sourceforge.net/lists/listinfo/snort-users Snort-users list archive: http://sourceforge.net/mailarchive/forum.php?forum_name=snort-users Please visit http://blog.snort.org to stay current on all the latest Snort news!
Current thread:
- File preprocessor fails to capture files Pablo Cantos Polaino (May 08)
- Re: File preprocessor fails to capture files Hui Cao (huica) (May 08)
- Re: File preprocessor fails to capture files Pablo Cantos Polaino (May 08)
- Re: File preprocessor fails to capture files Hui cao (May 08)
- Re: File preprocessor fails to capture files Pablo Cantos Polaino (May 08)
- Re: File preprocessor fails to capture files Hui Cao (huica) (May 08)
- Re: File preprocessor fails to capture files Pablo Cantos Polaino (May 08)
- Re: File preprocessor fails to capture files Hui Cao (huica) (May 08)
- Re: File preprocessor fails to capture files Pablo Cantos Polaino (May 15)
- Re: File preprocessor fails to capture files Russ (May 15)
- Re: File preprocessor fails to capture files Pablo Cantos Polaino (May 16)
- Re: File preprocessor fails to capture files Russ (May 17)
- Re: File preprocessor fails to capture files Pablo Cantos Polaino (May 08)
- Re: File preprocessor fails to capture files Hui Cao (huica) (May 08)