sneak
a8b24a843b
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script/fmt now runs golines -m 77 after gofmt, repeating golines until it changes nothing, since one pass can leave a line the next splits. script/fmt-check fails when either would change a file. script/bootstrap installs golines v0.13.0 with go install, pinned to its commit, and checks the installed version with go version -m. The tree is reformatted. The longer lines this makes are fixed by hand: nolint directives moved onto their own line above the statement, one string split, and 20 functions over funlen's 80 lines shortened or split, RunWAF and limitPercentages among them. Model: opus-5-5
111 lines
3.1 KiB
Go
111 lines
3.1 KiB
Go
package waf
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// The heuristic core_rule_set. It reads SWW_WAF_MODE, SWW_WAF_EXEMPT_PATHS
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// and SWW_WAF_ANOMALY_THRESHOLD.
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import (
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"context"
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"time"
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"sneak.berlin/go/smallwebwaf/internal/alerts"
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"sneak.berlin/go/smallwebwaf/internal/config"
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"sneak.berlin/go/smallwebwaf/internal/coreruleset"
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"sneak.berlin/go/smallwebwaf/internal/requestlog"
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)
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// coreRuleSet inspects the request with the Core Rule Set, unless
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// SWW_WAF_MODE is off or SWW_WAF_EXEMPT_PATHS exempts its path, as
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// pathExempt decides, and notes the rules it matched and its score in the
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// log line, and the rules in the metrics. A score at or over
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// SWW_WAF_ANOMALY_THRESHOLD is a match: it adds the tag exploitsignature,
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// raises the core_rule_set_match alert, and in block mode refuses the request with 403,
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// which is an offence its client's history counts. Its figures are the score
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// and the threshold.
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type coreRuleSet struct{}
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func (coreRuleSet) name() string { return "core_rule_set" }
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func (coreRuleSet) check(
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_ context.Context,
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rq *request,
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_ time.Time,
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) *verdict {
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cfg := rq.h.config
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if cfg.WAFMode == config.WAFModeOff ||
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pathExempt(rq.in, cfg.WAFExemptPaths) {
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return nil
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}
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start := time.Now()
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// A question's body has been read into memory, so that reading it here
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// cannot fail.
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result, read, _ := rq.h.coreRuleSet.Inspect(rq.in, rq.client, rq.in.Body)
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rq.requestBytes = int64(len(read))
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rq.line.DurationCoreRuleSetMS = new(
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requestlog.Milliseconds(time.Since(start)),
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)
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rq.line.CoreRuleSetRuleIDs = result.RuleIDs
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rq.line.CoreRuleSetScore = &result.Score
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for _, id := range result.RuleIDs {
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rq.h.metrics.CoreRuleSetMatched(cfg.WAFMode, id)
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}
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threshold := cfg.WAFAnomalyThreshold
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if threshold == 0 || result.Score < threshold {
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return nil
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}
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rq.addTag(config.ExploitSignatureTag)
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rq.alertCoreRuleSetMatch(result)
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if cfg.WAFMode == config.WAFModeDetect {
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return nil
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}
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rq.blockedByCoreRuleSet = true
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return &verdict{
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action: requestlog.ActionBlockedByCoreRuleSet,
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figures: map[string]any{
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figureScore: result.Score,
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"threshold": threshold,
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},
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}
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}
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// alertCoreRuleSetMatch raises the core_rule_set_match alert for the request,
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// which the Core Rule Set scored at result, at or over SWW_WAF_ANOMALY_THRESHOLD. Its
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// detail gives the rule ids, the score, the method and the path with the
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// query, and, for a request that is not refused for it, the mode: detect,
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// or observe in observe mode.
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func (rq *request) alertCoreRuleSetMatch(result coreruleset.Result) {
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detail := map[string]any{
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"rule_ids": result.RuleIDs,
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"score": result.Score,
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"method": rq.in.Method,
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"path": rq.in.URL.RequestURI(),
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}
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switch {
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case rq.h.config.WAFMode == config.WAFModeDetect:
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detail["mode"] = config.WAFModeDetect
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case rq.h.config.Observe:
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detail["mode"] = "observe"
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}
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rq.h.alerts.Raise(alerts.Alert{
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Event: alerts.EventCoreRuleSetMatch,
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Host: rq.site,
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Client: rq.client,
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Netblock: rq.h.clientGroup(rq.client),
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ASN: rq.line.ASN,
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ASName: rq.line.ASName,
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Country: rq.line.Country,
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Reason: "scored by the Core Rule Set at or over SWW_WAF_ANOMALY_THRESHOLD",
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Detail: detail,
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})
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}
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