Malicious PDF — malware analysis report

Static analysis result for SHA-256 c81f1b18548cbfa0…

MALICIOUS

PDF

34.8 KB Created: 2021-07-03 20:53:55 +07:00 Authoring application: wkhtmltopdf 0.12.6 (via Qt 4.8.7) First seen: 2026-06-04
MD5: 83139fa9d9d953f6389068291f3bbf89 SHA-1: 6aad5a06ac37f58b5ee3cdd0eb7a25031349e112 SHA-256: c81f1b18548cbfa0bf3386e9a18c0b14cbc6540f141c1c371ca6fafdfed2d43b
160 Risk Score

Malware Insights

MITRE ATT&CK
T1566.001 Spearphishing Attachment

The PDF document contains multiple links to known malicious redirectors and infrastructure, disguised as 'free generator' or 'game hack' lures for popular games like Roblox. The primary malicious URL identified is http://netcdn.tw/app/431946152/20210-robux-game-hack. The document body, though partially corrupted, contains references to these lures and URLs, reinforcing the social engineering aspect. No scripts were extracted, but the presence of malicious links and the ML classifier's high confidence indicate a high likelihood of this document being used for phishing or malware distribution.

Machine Learning

  • Nyx PDF Classifier malicious score 0.9980

Heuristics 4

  • PDF links to a 'free generator / game hack' redirector critical PDF_GAME_HACK_REDIRECT_LURE
    PDF's clickable action targets a redirector of the form /app/<id>/<slug>-game-hack — the landing-page shape of a large SEO 'free spins / generator / game hack' lure family that funnels victims through rotating disposable hosts to a malware/scam payload. The multi-link variants also trip ML/link-farm rules; this catches the single-link variants that otherwise score clean. CRITICAL on its own: the /app/<id>/<slug>-game-hack path shape is unambiguous scam infra, and the host rotates so a host-list match can't be relied on.
  • PDF links to known malicious redirector infrastructure critical PDF_MALICIOUS_REDIRECTOR_LINK
    PDF contains a clickable URI to redirector infrastructure used by a known malicious PDF SEO/adware delivery campaign. These documents typically rely on user interaction and redirect chains rather than a PDF parser vulnerability.
  • Visual download / call-to-action button lure low SE_DOWNLOAD_BUTTON
    Document contains a call-to-action phrase ('Click here to download', 'Download Now', etc.) — low-signal unless other findings point to a malicious workflow
  • Embedded URL info EMBEDDED_URL
    One or more URLs were extracted from the document. The URL itself is not a detection — see the per-URL labels for which channel (macro, JS, link annotation, document body, ...) reached each URL.
    URL http://netcdn.tw/app/431946152/20210-robux-game-hack In PDF document text
    • http://lib.icbc-indonesia.org/repository/roblox-its-not-free_GM431946152.pdfIn PDF document text
    • http://lib.icbc-indonesia.org/repository/earn-robux_GM431946152.pdfIn PDF document text
    • http://lib.icbc-indonesia.org//repository/coin-master-free-spins-link-iphone_GM406889139.pdfIn PDF document text
    • http://lib.icbc-indonesia.org//repository/www-coin-master-hack-xyz_GM406889139.pdfIn PDF document text
    • http://lib.icbc-indonesia.org//repository/make-robux_GM431946152.pdfIn PDF document text
    • http://lib.icbc-indonesia.org/repository/husky-roblox-free-robux_GM431946152.pdfIn PDF document text
    • http://lib.icbc-indonesia.org/repository/inspect-element-roblox-hack_GM431946152.pdfIn PDF document text
    • http://lib.icbc-indonesia.org/repository/how-to-get-free-robux-inspect-elemt_GM431946152.pdfIn PDF document text
    • http://lib.icbc-indonesia.org//repository/free-roblox-clothes-girl_GM431946152.pdfIn PDF document text
    • http://lib.icbc-indonesia.org//repository/give-me-robux-now_GM431946152.pdfIn PDF document text
    • http://lib.icbc-indonesia.org//repository/promo-codes-for-free-robux_GM431946152.pdfIn PDF document text
    • http://lib.icbc-indonesia.org/repository/free-robux-no-human-verification-or-survey-or-offers_GM431946152.pdfIn PDF document text
    • http://lib.icbc-indonesia.org/repository/prison-life-roblox-hacks_GM431946152.pdfIn PDF document text
    • http://lib.icbc-indonesia.org//repository/can-lucky-patcher-hack-coin-master_GM406889139.pdfIn PDF document text
    • http://lib.icbc-indonesia.org//repository/play-full-version-of-minecraft-for-free-no-download_GM479516143.pdfIn PDF document text
    • http://lib.icbc-indonesia.org/repository/how-to-get-free-robux-instantly_GM431946152.pdfIn PDF document text
    • http://lib.icbc-indonesia.org/repository/kidnap-cheat-roblox_GM431946152.pdfIn PDF document text
    • http://lib.icbc-indonesia.org//repository/coin-master-free-link-daily_GM406889139.pdfIn PDF document text
    • http://lib.icbc-indonesia.org/repository/free-robux-giftcard-codes-2021_GM431946152.pdfIn PDF document text
    • http://lib.icbc-indonesia.org/repository/free-roblox-hacker-com-free-roblox-hack_GM431946152.pdfIn PDF document text
    • http://en.wikipedia.org/wiki/MIT_LicenseIn PDF document text

Extracted artifacts 2

Files carved from inside the sample during analysis.

FilenameKindSourceSize
font_00_sfnt_off00003054.bin pdf-font-stream PDF embedded font (sfnt) at offset 0x3054 22732 bytes
SHA-256: 265826de9b52b0fded4f7e80170d72f8d55f774dc718efdf96001be1fbfd4fe9
font_01_sfnt_off0000633c.bin pdf-font-stream PDF embedded font (sfnt) at offset 0x633C 18956 bytes
SHA-256: 75ea27529c0c01066f51b2c4a610dacd0c00866775fa9ae9f69139e6484c1ffd

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