[Evergreen-general] Question about search engine bots & DB CPU spikes

[JonGeorg SageLibrary]

The LONG STRING sometimes contains a word, but it's usually just a string
of numbers repeated, like this- $_78110$[$_78110$, $_78110$$_78110$),
$_78110$]$_78110$, $_78110$$_78110$. The numbers change which is why I
suspect it's a SQL injection attempt.

I agree re blocking by IP's. I didn't set the robots file crawl time any
higher as I wanted to see what, if any, effect the initial change had
during an attack.
-Jon

On Wed, Dec 1, 2021 at 11:27 AM Jeff Davis via Evergreen-general <
evergreen-general at list.evergreen-ils.org> wrote:

> Our robots.txt file (https://catalogue.libraries.coop/robots.txt)
> throttles Googlebot and Bingbot to 60 seconds and disallows certain
> other crawlers entirely.  So even 10 seconds seems generous to me.
>
> Of course, robots.txt will only be respected by well-behaved crawlers;
> there's nothing preventing a bot from ignoring it (in which case, as
> Jason says, your best bet may be to block the offending IP).
>
> Is the "LONG_STRING" in your examples a legitimate search -- i.e, no
> unusual characters or obvious SQL injection attempts?  Does it contain
> complex nesting of search terms?
>
> Jeff
>
>
> On 2021-11-30 6:34 p.m., JonGeorg SageLibrary via Evergreen-general wrote:
> > Question. We've been getting hammered by search engine bots [?], but
> > they seem to all query our system at the same time. Enough that it's
> > crashing the app servers. We have a robots.txt file in place. I've
> > increased the crawling delay speed from 3 to 10 seconds, and have
> > explicitly disallowed the specific bots, but I've seen no change from
> > the worst offenders - Bingbot and UT-Dorkbot. We had over 4k hits from
> > Dorkbot alone from 2pm-5pm today, and over 5k from Bingbot in the same
> > timeframe. All a couple hours after I made the changes to the robots
> > file and restarted apache services. Which out of 100k entries in the
> > vhosts files in that time frame doesn't sound like a lot, but the rest
> > of the traffic looks normal. This issue has been happening
> > intermittently [last 3 are 11/30, 11/3, 7/20] for a while, and the only
> > thing that seems to work is to manually kill the services on the DB
> > servers and restart services on the application servers.
> >
> > The symptom is an immediate spike in the Database CPU load. I start
> > killing all queries older than 2 minutes, but it still usually
> > overwhelms the system causing the app servers to stop serving requests.
> > The stuck queries are almost always ones along the lines of:
> >
> > -- bib search: #CD_documentLength #CD_meanHarmonic #CD_uniqueWords
> > from_metarecord(*/BIB_RECORD#/*) core_limit(100000)
> > badge_orgs(1,138,151) estimation_strategy(inclusion) skip_check(0)
> > check_limit(1000) sort(1) filter_group_entry(1) 1
> > site(*/LIBRARY_BRANCH/*) depth(2)
> >                      +
> >                   |       |         WITH w AS (
> >                  |       | WITH */STRING/*_keyword_xq AS (SELECT
> >                                                  +
> >                   |       |       (to_tsquery('english_nostop',
> > COALESCE(NULLIF( '(' ||
> >
> btrim(regexp_replace(split_date_range(search_normalize(replace(replace(uppercase(translate_isbn1013(E'1')),
>
> > */LONG_STRING/*))),E'(?:\\s+|:)','&','g'),'&|')  || ')', '()'), '')) ||
> > to_tsquery('simple', COALESCE(NULLIF( '(' ||
> >
> btrim(regexp_replace(split_date_range(search_normalize(replace(replace(uppercase(translate_isbn1013(E'1')),
>
> > */LONG_STRING/*))),E'(?:\\s+|:)','&','g'),'&|')  || ')', '()'), ''))) AS
> > tsq,+
> >                   |       |       (to_tsquery('english_nostop',
> > COALESCE(NULLIF( '(' ||
> > btrim(regexp_replace(split_date_range(search_normalize
> >   00:02:17.319491 | */STRING/* |
> >
> > And the queries by DorkBot look like they could be starting the query
> > since it's using the basket function in the OPAC.
> >
> > "GET
> >
> /eg/opac/results?do_basket_action=Go&query=1&detail_record_view=*/LONG_STRING/*&search-submit-go=Search&no_highlight=1&modifier=metabib&select_basket_action=1&qtype=keyword&fg%3Amat_format=1&locg=112&sort=1
>
> > HTTP/1.0" 500 16796 "-" "UT-Dorkbot/1.0"
> >
> > I've anonymized the output just to be cautious. Reports are run off the
> > backup database server, so it cannot be an auto generated report, and it
> > doesn't happen often enough for that either. At this point I'm tempted
> > to block the IP addresses. What strategies are you all using to deal
> > with crawlers, and does anyone have an idea what is causing this?
> > -Jon
> >
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> >
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