Fix bug: remove eval()/Pug SSTI of username in GET /profile - #333
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Signed-off-by: Devin <devin@cognition.ai>
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🔍 RSN verification remains unconfirmed
These changes affect existing challenge behavior, so repository rules require npm run rsn. Verify the Refactoring Safety Net passes before merging.
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| const username = user.username | ||
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| if (username?.match(/#{(.*)}/) !== null && utils.isChallengeEnabled(challenges.usernameXssChallenge)) { | ||
| req.app.locals.abused_ssti_bug = true |
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🟡 Inert username falsely solves SSTi
Any #{...} username sets abused_ssti_bug although Pug now escapes it. The server-side verifier then awards SSTi without command execution.
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The global abused_ssti_bug flag records whether the SSTi exploit occurred. This assignment now records only that a username matched the old payload syntax. The username is passed as a Pug local and escaped, so no template evaluation or command execution occurs. The server-side verifier trusts this flag and solves sstiChallenge on the next request with the known key.
Example: Set the username to #{1+1}, load /profile, then request /solve/challenges/server-side?key=tRy_H4rd3r_n0thIng_iS_Imp0ssibl3. The challenge becomes solved although the page displays #{1+1} and no command ran.
Recommended fix: Remove this obsolete marker path and retire or redesign the SSTi challenge verification. Do not set an exploit-success flag from payload shape alone.
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| div.s12.m12.l6 | ||
| img.img-rounded(src=profileImage, alt='profile picture', width='90%', height='236', style='margin-right: 5%; margin-left: 5%;') | ||
| p(style='margin-top: 8px; color: _textColor_; text-align: center;') _username_ | ||
| p(style='margin-top: 8px; color: _textColor_; text-align: center;')= username |
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🟡 Escaped payload falsely solves CSP Bypass
An escaped script username still satisfies usernameXssChallenge when the profile image injects unsafe-inline. Loading the profile awards CSP Bypass without executing XSS.
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The profile previously inserted the username into Pug source, allowing the challenge payload to become executable markup after CSP injection. The new = interpolation correctly escapes the username into text. However, solveIf still awards usernameXssChallenge from the raw username and profile-image strings alone. It does not observe browser execution, so the now-inert payload still solves the challenge.
Example: Store <script>alert(xss)</script> as the username and a profile image ending in ; script-src 'unsafe-inline'. A GET of /profile renders escaped text but marks CSP Bypass solved.
Recommended fix: Remove or redesign the obsolete challenge solver and its metadata alongside the rendering fix. Challenge completion must not rely on a raw payload that the response escapes.
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| describe('challenge "usernameXss"', () => { | ||
| it('Username field should be susceptible to XSS attacks after disarming CSP via profile image URL', () => { | ||
| describe('username rendering', () => { |
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🔍 Challenge coverage no longer verifies completion
Rendering checks replace both challenge-completion tests. Update or retire the affected challenge flows, then preserve E2E coverage for their resulting lifecycle.
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Description
Fixes server-side RCE / SSTI in
GET /profile(routes/userProfile.ts). The logged-in user'susername(attacker-controlled viaPOST /profile) was matched against/#{(.*)}/, the inner code was passed toeval(), and the result was string-spliced into the Pug template source beforepug.compile().Changes:
eval()branch entirely; keepreq.app.locals.abused_ssti_bug = truemarker so the existing SSTi verification check keeps working._username_into the template source.views/userProfile.pugnow rendersp(...)= username, receiving the value as an escaped template local (fn({ ..., username })), so no user data reaches the Pug compiler oreval.#{...}username is rendered verbatim (not evaluated) and Cypress spec updated accordingly.Resolved or fixed issue: none
AI Tool Disclosure
Devin (Cognition AI)DevinFix security finding: server-side RCE via eval() of attacker-controlled username (SSTI) in routes/userProfile.ts; implement fix and open PR.Affirmation
Devin-Org: engineering