Malicious PDF — malware analysis report

Static analysis result for SHA-256 5f3bcc816d3405bc…

MALICIOUS

PDF

32.1 KB Created: 2021-07-19 18:21:37 +07:00 Authoring application: wkhtmltopdf 0.12.6 (via Qt 4.8.7) First seen: 2026-06-04
MD5: 28b887793d2ca4f59d6d444e780ff7b4 SHA-1: 79b460c2cbe09c8773dfa963a910f79901a5159d SHA-256: 5f3bcc816d3405bcd039c859a2c702de5eba7ce1b0aff9939a62fbaec4019081
180 Risk Score

Malware Insights

MITRE ATT&CK
T1566.001 Spearphishing Attachment

The PDF contains multiple links to known malicious redirectors, specifically advertising free game currency and hacks. The primary redirector, http://netcdn.tw/app/431946152/free-robux-game-hack, is a critical finding. While no scripts were explicitly extracted, the malformed stream length and ML classifier indicate exploitation attempts, likely leveraging embedded JavaScript for redirection.

Machine Learning

  • Nyx PDF Classifier malicious score 0.9930

Heuristics 5

  • 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.
  • Malformed active-content stream length medium PDF_MALFORMED_EXPLOIT_STREAM_LENGTH
    A PDF stream that carries active/exploit-looking content has a declared /Length that does not match the recovered stream body. Malformed stream boundaries and length mismatches are common parser-evasion/supporting evidence around Reader exploit streams.
  • 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/free-robux-game-hack In PDF document text
    • http://www.duchem.ae/uploaded_files/userfiles/files/coin-master-free-daily-spins_GM406889139.pdfIn PDF document text
    • http://www.duchem.ae/uploaded_files/userfiles/files/free-robux-co_GM431946152.pdfIn PDF document text
    • http://www.duchem.ae/uploaded_files/userfiles/files/how-do-you-get-minecraft-for-free_GM479516143.pdfIn PDF document text
    • http://www.duchem.ae/uploaded_files/userfiles/files/minecraft-java-edition-download-free_GM479516143.pdfIn PDF document text
    • http://www.duchem.ae/uploaded_files/userfiles/files/free-spins-from-coin-master_GM406889139.pdfIn PDF document text
    • http://www.duchem.ae/uploaded_files/userfiles/files/how-to-get-free-robux-without-verifying-2021_GM431946152.pdfIn PDF document text
    • http://www.duchem.ae/uploaded_files/userfiles/files/free-robux-no-verification-no-survey_GM431946152.pdfIn PDF document text
    • http://www.duchem.ae/uploaded_files/userfiles/files/coin-master-free-spins-daily_GM406889139.pdfIn PDF document text
    • http://www.duchem.ae/uploaded_files/userfiles/files/minecraft-redeem-code-free_GM479516143.pdfIn PDF document text
    • http://www.duchem.ae/uploaded_files/userfiles/files/coin-master-daily-free-spins-blogspot_GM406889139.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_off00002959.bin pdf-font-stream PDF embedded font (sfnt) at offset 0x2959 22528 bytes
SHA-256: 6708bbc8777a5b47e10f2f7b44c41e5d2c7aff97d8054a1f084b52d265fa7bb9
font_01_sfnt_off00005bd5.bin pdf-font-stream PDF embedded font (sfnt) at offset 0x5BD5 18200 bytes
SHA-256: af0a6f01588019b38fd5688102a8ebe17e4b5155afa3360a762aee3dff872896

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