Malicious PDF — malware analysis report

Static analysis result for SHA-256 d1b861b39fd54421…

MALICIOUS

PDF

35.0 KB Created: 2021-07-19 21:54:12 +07:00 Authoring application: wkhtmltopdf 0.12.6 (via Qt 4.8.7) First seen: 2026-06-04
MD5: bd07d95e927ac0ca3d435c13cc34acc0 SHA-1: 2f7aaa1c6747fe77532c9088d55fbb46af893afd SHA-256: d1b861b39fd54421d770cbc12977ce8a64e3b4c4cf6505fc501373cf11d50432
180 Risk Score

Malware Insights

MITRE ATT&CK
T1566.001 Spearphishing Attachment

The PDF contains a malicious redirector link disguised as a "Coin Master Free Spins" lure, aiming to trick users into visiting potentially harmful websites. The malformed stream length and ML classifier indicate a high likelihood of malicious intent. Although no scripts were directly extracted, the PDF structure and embedded links suggest it's designed to lead users to exploit or phishing sites.

Machine Learning

  • Nyx PDF Classifier malicious score 0.9973

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/406889139/coin-master-free-spins-link-blogspot-2021-game-hack In PDF document text
    • https://knj.com.tw/image/data/files/free-robux-generator-no-verification-2021_GM431946152.pdfIn PDF document text
    • https://knj.com.tw/image/data/files/best-minecraft-hacked-client_GM479516143.pdfIn PDF document text
    • https://knj.com.tw/image/data/files/how-to-hack-minecraft_GM479516143.pdfIn PDF document text
    • https://knj.com.tw/image/data/files/minecraft-free-trial_GM479516143.pdfIn PDF document text
    • https://knj.com.tw/image/data/files/how-to-get-minecraft-bedrock-edition-for-free_GM479516143.pdfIn PDF document text
    • https://knj.com.tw/image/data/files/minecraft-redeem-code-free_GM479516143.pdfIn PDF document text
    • https://knj.com.tw/image/data/files/how-to-get-free-robux-without-verifying-2021_GM431946152.pdfIn PDF document text
    • https://knj.com.tw/image/data/files/how-to-get-minecraft-windows-10-for-free_GM479516143.pdfIn PDF document text
    • https://knj.com.tw/image/data/files/free-spins-for-coin-master-2021_GM406889139.pdfIn PDF document text
    • https://knj.com.tw/image/data/files/free-spins-for-coin-master_GM406889139.pdfIn PDF document text
    • http://en.wikipedia.org/wiki/MIT_LicenseIn PDF document text

Related samples 8

Ranked by shared artifacts, heuristics, extracted URLs, CVEs, and signatures.

Full JSON: related samples API

Extracted artifacts 2

Files carved from inside the sample during analysis.

FilenameKindSourceSize
stream_002_off00002f5c.bin decompressed-pdf-stream PDF FlateDecoded stream at offset 0x2F5C 23460 bytes
SHA-256: a9996ecd21765ee08ca2d897662d432d5d5a6704845a16ad217cd78711c349fa
font_01_sfnt_off00006496.bin pdf-font-stream PDF embedded font (sfnt) at offset 0x6496 19036 bytes
SHA-256: a1db0e26d638f2546736f1f7b434dee98a1c5e726f40723477b7c203db66759e

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