Malicious PDF — malware analysis report

Static analysis result for SHA-256 1840bcf7f781be7e…

MALICIOUS

PDF

34.0 KB Created: 2021-07-20 15:24:01 +07:00 Authoring application: wkhtmltopdf 0.12.6 (via Qt 4.8.7) First seen: 2021-10-24
MD5: 05cdd299f3ad28cfd7331582de354ceb SHA-1: 3989967c353b57b897a71cbaf33253c5ac8e03fb SHA-256: 1840bcf7f781be7e23c7729416fb164c7d93c894a97b0269f4a52067aeb6603a
180 Risk Score

Malware Insights

MITRE ATT&CK
T1566.001 Spearphishing Attachment

The PDF contains a malicious link disguised as a "free generator / game hack" lure, which redirects to known malicious infrastructure. The malformed stream length heuristic and ML classifier further indicate malicious intent. Although no scripts were explicitly extracted, the PDF structure and embedded links suggest an attempt to redirect the user to a site that likely hosts further malicious content or exploits.

Machine Learning

  • Nyx PDF Classifier malicious score 0.9955

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/free-coins-coin-master-2021-game-hack In PDF document text
    • http://smagripadps.sch.id/new/public/ckfinder/userfiles/files/how-to-get-free-robux-2021_GM431946152.pdfIn PDF document text
    • http://smagripadps.sch.id/new/public/ckfinder/userfiles/files/roblox-robux-hack_GM431946152.pdfIn PDF document text
    • http://smagripadps.sch.id/new/public/ckfinder/userfiles/files/free-tiktok-followers-no-human-verification-or-survey_GM835599320.pdfIn PDF document text
    • http://smagripadps.sch.id/new/public/ckfinder/userfiles/files/free-tiktok-bots_GM835599320.pdfIn PDF document text
    • http://smagripadps.sch.id/new/public/ckfinder/userfiles/files/free-coins-and-spins-for-coin-master_GM406889139.pdfIn PDF document text
    • http://smagripadps.sch.id/new/public/ckfinder/userfiles/files/minecraft-online-free-download_GM479516143.pdfIn PDF document text
    • http://smagripadps.sch.id/new/public/ckfinder/userfiles/files/free-tiktok-followers-no-human-verification_GM835599320.pdfIn PDF document text
    • http://smagripadps.sch.id/new/public/ckfinder/userfiles/files/minecraft-gun-games-free_GM479516143.pdfIn PDF document text
    • http://smagripadps.sch.id/new/public/ckfinder/userfiles/files/ways-to-get-free-robux_GM431946152.pdfIn PDF document text
    • http://smagripadps.sch.id/new/public/ckfinder/userfiles/files/free-minecraft-server-hosting-24-7_GM479516143.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
stream_002_off00002f95.bin decompressed-pdf-stream PDF FlateDecoded stream at offset 0x2F95 23040 bytes
SHA-256: 16777ef448ef41310af57a354091dc04c2c51bbdb45e52b5e34798ccae55a565
font_01_sfnt_off00006389.bin pdf-font-stream PDF embedded font (sfnt) at offset 0x6389 18112 bytes
SHA-256: 0727bd4027d3f5eec951b181c2bc31ee4d98e10eed2c862aff41d240a04f60ea

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