Snort mailing list archives
Re: Snort 2.8.6 and gzip decoding functionality not working for me
From: L0rd Ch0de1m0rt <l0rdch0de1m0rt () gmail com>
Date: Tue, 4 May 2010 15:31:36 -0500
Matts, thanks for the responses. Using the config options that Watchinski provided yielded the same results as initially described. Bhagya, I think I have streams enabled; please correct me if I am wrong: # cat /etc/snort/snort.conf | grep -i -A 10 stream # Target-Based stateful inspection/stream reassembly. For more inforation, see README.stream5 preprocessor stream5_global: max_tcp 8192, track_tcp yes, track_udp yes, track_icmp no preprocessor stream5_tcp: policy windows, detect_anomalies, require_3whs 180, \ overlap_limit 10, check_session_hijacking, small_segments 3 bytes 150, timeout 180, \ ports client 21 22 23 25 42 53 79 80 109 110 111 113 119 135 136 137 139 143 110 \ 111 161 445 513 514 691 1220 1433 1521 2100 2301 3128 3306 6665 6666 6667 6668 6669 \ 7000 8000 8080 8180 8888 32770 32771 32772 32773 32774 32775 32776 32777 32778 32779, \ ports both 443 465 563 636 989 992 993 994 995 7801 7702 7900 7901 7902 7903 7904 7905 \ 7906 6907 7908 7909 7910 7911 7912 7913 7914 7915 7916 7917 7918 7919 7920 preprocessor stream5_udp: timeout 180 # performance statistics. For more information, see the Snort Manual, Configuring Snort - Preprocessors - Performance Monitor # preprocessor perfmonitor: time 300 file /var/snort/snort.stats pktcnt 10000 # HTTP normalization and anomaly detection. For more information, see README.http_inspect # preprocessor http_inspect: global iis_unicode_map unicode.map 1252 preprocessor http_inspect: global iis_unicode_map unicode.map 1252 compress_depth 20480 decompress_depth 20480 preprocessor http_inspect_server: server default \ apache_whitespace no \ ascii no \ As for pcaps, yes they can be provided but I have looked in to them myself and have confirmed the behaviour described. I am concerned about anonamyzing them since the google javascript data may contain PII in the URI and/or cookies. Do you know of a good site that uses gzip without PII that I can use to test and give you pcaps? Thanks again. Cheers, -L0rd Ch0de1m0rt On Tue, May 4, 2010 at 3:18 PM, Bhagya Bantwal <bbantwal () sourcefire com> wrote:
Turning on stream reassembly might be useful too. Do you have a pcap we could look into? -B On Tue, May 4, 2010 at 3:40 PM, L0rd Ch0de1m0rt <l0rdch0de1m0rt () gmail com> wrote:Hello. I am experimenting with snort v2.8.6 and hope to benefit from its gzip decoding capabilities. However, I have been unsuccessful so far in getting it to work. I am fetching a javascript file from google and clearly it is encoding it using gzip. This rule alerts me: alert tcp any any -> any any (msg:"gzip encoding detected from server"; flow:established,from_server; content:"|0d 0a|Content-Encoding: gzip|0d 0a|"; nocase; classtype:attempted-user; sid:3141591; rev:1;) BUT this rule does not alert when it is clearly in the gzip decoded data: alert tcp any any -> any any (msg:"detected on gzip decoded data from Google"; flow:established,from_server; content:"google.isOpera=false"; nocase; classtype:attempted-user; sid:3141592; rev:1;) I am using the defaults for the gzip portion of the http_inspect preprocessor and the content trying to be matched (google.isOpera=false) is in the first few hundred bytes of the data. Here is my snort.conf http_inspect details: preprocessor http_inspect: global iis_unicode_map unicode.map 1252 preprocessor http_inspect_server: server default \ apache_whitespace no \ ascii no \ bare_byte no \ chunk_length 500000 \ server_flow_depth 0 \ client_flow_depth 0 \ post_depth 65495 \ directory no \ double_decode no \ iis_backslash no \ iis_delimiter no \ iis_unicode no \ multi_slash no \ non_strict \ oversize_dir_length 500 \ ports { 80 1220 2301 3128 7777 7779 8000 8008 8028 8080 8180 8888 9999 } \ u_encode yes \ non_rfc_char { 0x00 0x01 0x02 0x03 0x04 0x05 0x06 0x07 } \ webroot no \ extended_response_inspection \ inspect_gzip I configured snort with --enable-zlib before I compiled and I get this on snort startup: Using ZLIB version: 1.2.3.3 What am I doing wrong here? Thanks for any help. Cheers, -L0rd Ch0de1m0rt ------------------------------------------------------------------------------ _______________________________________________ Snort-sigs mailing list Snort-sigs () lists sourceforge net https://lists.sourceforge.net/lists/listinfo/snort-sigs
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Current thread:
- Snort 2.8.6 and gzip decoding functionality not working for me L0rd Ch0de1m0rt (May 04)
- Re: Snort 2.8.6 and gzip decoding functionality not working for me Matt Olney (May 04)
- Re: Snort 2.8.6 and gzip decoding functionality not working for me Matt Watchinski (May 04)
- Re: Snort 2.8.6 and gzip decoding functionality not working for me Bhagya Bantwal (May 04)
- Re: Snort 2.8.6 and gzip decoding functionality not working for me L0rd Ch0de1m0rt (May 04)
- Re: Snort 2.8.6 and gzip decoding functionality not working for me Matt Watchinski (May 04)
- Re: Snort 2.8.6 and gzip decoding functionality not working for me L0rd Ch0de1m0rt (May 05)
- Re: Snort 2.8.6 and gzip decoding functionality not working for me Jason Wallace (May 06)
- Re: Snort 2.8.6 and gzip decoding functionality not working for me Matt Olney (May 06)
- Re: Snort 2.8.6 and gzip decoding functionality not working for me Nerijus Krukauskas (May 14)
- Re: Snort 2.8.6 and gzip decoding functionality not working for me L0rd Ch0de1m0rt (May 04)