From 21947c9c13fafbf0ba110f4c8146d78302dc99cd Mon Sep 17 00:00:00 2001
From: Vadim Kibana <82822460+vadimkibana@users.noreply.github.com>
Date: Wed, 8 Jan 2025 08:36:52 +0100
Subject: [PATCH] [ES|QL] Escape backslashes last (#205680)

## Summary

Closes https://github.com/elastic/kibana-team/issues/1365
https://github.com/elastic/kibana/security/code-scanning/500

Moves backslash un-escaping last, after rall other un-escaping.

### Checklist

Check the PR satisfies following conditions.

Reviewers should verify this PR satisfies this list as well.

- [ ] Any text added follows [EUI's writing
guidelines](https://elastic.github.io/eui/#/guidelines/writing), uses
sentence case text and includes [i18n
support](https://github.com/elastic/kibana/blob/main/src/platform/packages/shared/kbn-i18n/README.md)
- [ ]
[Documentation](https://www.elastic.co/guide/en/kibana/master/development-documentation.html)
was added for features that require explanation or tutorials
- [ ] [Unit or functional
tests](https://www.elastic.co/guide/en/kibana/master/development-tests.html)
were updated or added to match the most common scenarios
- [ ] If a plugin configuration key changed, check if it needs to be
allowlisted in the cloud and added to the [docker
list](https://github.com/elastic/kibana/blob/main/src/dev/build/tasks/os_packages/docker_generator/resources/base/bin/kibana-docker)
- [ ] This was checked for breaking HTTP API changes, and any breaking
changes have been approved by the breaking-change committee. The
`release_note:breaking` label should be applied in these situations.
- [ ] [Flaky Test
Runner](https://ci-stats.kibana.dev/trigger_flaky_test_runner/1) was
used on any tests changed
- [ ] The PR description includes the appropriate Release Notes section,
and the correct `release_note:*` label is applied per the
[guidelines](https://www.elastic.co/guide/en/kibana/master/contributing.html#kibana-release-notes-process)

### Identify risks

Does this PR introduce any risks? For example, consider risks like hard
to test bugs, performance regression, potential of data loss.

Describe the risk, its severity, and mitigation for each identified
risk. Invite stakeholders and evaluate how to proceed before merging.

- [ ] [See some risk
examples](https://github.com/elastic/kibana/blob/main/RISK_MATRIX.mdx)
- [ ] ...

(cherry picked from commit 3d9f34c6ddd26f628654ff1437e3fd047e2e3c53)
---
 .../src/parser/__tests__/literal.test.ts      | 36 +++++++++++++++++++
 .../kbn-esql-ast/src/parser/factories.ts      |  4 +--
 2 files changed, 38 insertions(+), 2 deletions(-)

diff --git a/src/platform/packages/shared/kbn-esql-ast/src/parser/__tests__/literal.test.ts b/src/platform/packages/shared/kbn-esql-ast/src/parser/__tests__/literal.test.ts
index 71ae3603c9c20..356daf8aa43ce 100644
--- a/src/platform/packages/shared/kbn-esql-ast/src/parser/__tests__/literal.test.ts
+++ b/src/platform/packages/shared/kbn-esql-ast/src/parser/__tests__/literal.test.ts
@@ -116,6 +116,42 @@ describe('literal expression', () => {
           ],
         });
       });
+
+      it('escape double-quote before backslash', () => {
+        const text = `ROW "a\\"\\\\b", 1`;
+        const { root } = parse(text);
+
+        expect(root.commands[0]).toMatchObject({
+          type: 'command',
+          args: [
+            {
+              type: 'literal',
+              literalType: 'keyword',
+              name: '"a\\"\\\\b"',
+              valueUnquoted: 'a"\\b',
+            },
+            {},
+          ],
+        });
+      });
+
+      it('escape backslash before double-quote', () => {
+        const text = `ROW "a\\\\\\"b", 1`;
+        const { root } = parse(text);
+
+        expect(root.commands[0]).toMatchObject({
+          type: 'command',
+          args: [
+            {
+              type: 'literal',
+              literalType: 'keyword',
+              name: '"a\\\\\\"b"',
+              valueUnquoted: 'a\\"b',
+            },
+            {},
+          ],
+        });
+      });
     });
 
     describe('triple quoted', () => {
diff --git a/src/platform/packages/shared/kbn-esql-ast/src/parser/factories.ts b/src/platform/packages/shared/kbn-esql-ast/src/parser/factories.ts
index 0db09c0f9dfa7..735c80dc26283 100644
--- a/src/platform/packages/shared/kbn-esql-ast/src/parser/factories.ts
+++ b/src/platform/packages/shared/kbn-esql-ast/src/parser/factories.ts
@@ -127,11 +127,11 @@ export function createLiteralString(ctx: StringContext): ESQLLiteral {
 
   if (!isTripleQuoted) {
     valueUnquoted = valueUnquoted
-      .replace(/\\\\/g, '\\')
       .replace(/\\"/g, '"')
       .replace(/\\r/g, '\r')
       .replace(/\\n/g, '\n')
-      .replace(/\\t/g, '\t');
+      .replace(/\\t/g, '\t')
+      .replace(/\\\\/g, '\\');
   }
 
   return Builder.expression.literal.string(