CVE-2017-20202 json
Web Developer for Chrome v0.4.9 Malicious Backdoor Supply Chain Compromise
published last yr. modified 4mo ago also EUVD-2025-33277
- cvss
- 9.3
- version 4.0, CNA
- cisa kev
- Not listed
- not in CISA's catalog
- epss
- 0.5%
- EPSS 0.5% chance of exploitation in 30 days, percentile 45%
- public exploits
- 0
- none known
Summary
Web Developer for Chrome v0.4.9 contained malicious code that generated a domain via a DGA and fetched a remote script. The fetched script conditionally loaded follow-on modules that performed extensive ad substitution and malvertising, displayed fake “repair” alerts that redirected users to affiliate programs, and attempted to harvest credentials when users logged in. Injected components enumerate common banner sizes for substitution, replace third-party ad calls, and redirect victim traffic to affiliate landing pages. Potential impacts include user-level code execution in the browser context, large-scale ad fraud and traffic hijacking, credential theft, and exposure to additional payloads delivered by the actor. The compromise was reported on by the maintainer of Web Developer for Chrome on August 2, 2017 and remediated in v0.5.0.
Patch / fix
Is CVE-2017-20202 in your stack? Fencer shows which of your repositories are affected as soon as an advisory lands, and opens the fix as a pull request.
Check with FencerCISA SSVC
- Exploitation
- Proof of concept is public
- Automatable
- no
- Technical impact
- total
- Assessed
- last yr.
Exploit prediction
0.54% chance of exploitation in the next 30 days, higher than 45% of all scored CVEs (FIRST EPSS, 2026-11-09).
Exploits and checks
- proofpoint.com https://www.proofpoint.com/us/threat-insight/post/threat-actor-goes-chrome-extension-hijacking-spree referenced PoC, tagged "exploit" by a source, unverified
- gist.github.com https://gist.github.com/piedpiperRichard/076516da60f45842f1a6e6ae35a9a240/ referenced PoC, tagged "exploit" by a source, unverified
CVSS scores
| assigned by | version | score | vector |
|---|---|---|---|
| CNA | 4.0 | 9.3 | CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:H/VI:H/VA:N/SC:H/SI:H/SA:N |
| CNA | 4.0 | 9.3 | CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:H/VI:H/VA:N/SC:H/SI:H/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X |
Affected products
- Web Developer for Chrome Web Developer for Chrome
Classification
- Weakness
-
- CWE-506 Embedded Malicious Code
References
-
web.archive.org
/web/20170803163618/https://chrispederick.com/blog/web-developer-for-chrome-compromised/
vendor-advisory, patch
-
proofpoint.com
/us/threat-insight/post/threat-actor-goes-chrome-extension-hijacking-spree
technical-description, exploit
-
gist.github.com
/piedpiperRichard/076516da60f45842f1a6e6ae35a9a240/
exploit
-
ui.vision
/blog/chrome-extension-adware/
technical-description
-
chromewebstore.google.com
/detail/web-developer/bfbameneiokkgbdmiekhjnmfkcnldhhm?pli=1
product
-
vulncheck.com
/advisories/web-developer-for-chrome-malicious-backdoor-supply-chain-compromise
third-party-advisory
Sources
- CVE List CVE-2017-20202
- NVD CVE-2017-20202
Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.