Malicious PDF — malware analysis report

Static analysis result for SHA-256 3890d3d31f0be239…

MALICIOUS

PDF

42.6 KB Created: 2021-05-14 21:00:21 +07:00 Authoring application: wkhtmltopdf 0.12.6 (via Qt 4.8.7) First seen: 2021-09-15
MD5: 57bc9c4940c19f687beede7daf329cb2 SHA-1: d2cd901d80d9b41110f894e83f56c76364068fc5 SHA-256: 3890d3d31f0be239e381f54dc646a2d13ca9e86cd84e712af1a10896d1827921
142 Risk Score

Malware Insights

MITRE ATT&CK
T1566.001 Spearphishing Attachment T1203 Exploitation for Client Execution

The PDF document contains numerous links to external websites, many of which are structured as SEO-optimized PDF gateways for game-related cheats and hacks. The presence of a fake CAPTCHA heuristic suggests an attempt to trick the user into interacting further, likely leading to a download or execution of a malicious payload. The ML classifier strongly indicates malicious intent.

Machine Learning

  • Nyx PDF Classifier malicious score 0.9971

Heuristics 5

  • Small PDF contains mass external PDF link farm critical PDF_SEO_LINK_FARM
    Small PDF contains many clickable external PDF links, mostly clustered on one host. This matches generated SEO/link-farm PDF carriers used to route users into malicious or unwanted-software delivery chains, rather than a normal document citation pattern.
  • Fake CAPTCHA / human verification prompt high SE_FAKE_CAPTCHA
    Document displays a fake CAPTCHA or human-verification prompt — used to trick users into running commands or pressing keyboard shortcuts
  • 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
  • External URI info PDF_URI
    PDF contains an external URL action
  • 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 https://netcdn.xyz/app/406889139/coin-master-free-spin-software-game-hack PDF link annotation
    • http://ntweac.edu.hk/admin/ckfinder/userfiles/files/how-to-hack-a-minecraft-server_GM479516143.pdfIn PDF document text
    • http://ntweac.edu.hk/admin/ckfinder/userfiles/files/how-to-get-free-robux-without-downloading-anything_GM431946152.pdfIn PDF document text
    • http://ntweac.edu.hk/admin/ckfinder/userfiles/files/but-link-says-free-robux_GM431946152.pdfIn PDF document text
    • http://ntweac.edu.hk/admin/ckfinder/userfiles/files/master-coin-free-spin-daily_GM406889139.pdfIn PDF document text
    • http://ntweac.edu.hk/admin/ckfinder/userfiles/files/free-roblox-girl-clothes_GM431946152.pdfIn PDF document text
    • http://ntweac.edu.hk/admin/ckfinder/userfiles/files/earn-free-robux_GM431946152.pdfIn PDF document text
    • http://ntweac.edu.hk/admin/ckfinder/userfiles/files/coin-master-free-spins-and-coins-group_GM406889139.pdfIn PDF document text
    • http://ntweac.edu.hk/admin/ckfinder/userfiles/files/today-free-spin-coin-master_GM406889139.pdfIn PDF document text
    • http://ntweac.edu.hk/admin/ckfinder/userfiles/files/rewardrobux-com_GM431946152.pdfIn PDF document text
    • http://ntweac.edu.hk/admin/ckfinder/userfiles/files/android-coin-master-3433-apk-hack_GM406889139.pdfIn PDF document text
    • http://ntweac.edu.hk/admin/ckfinder/userfiles/files/minecraft-free-download-pc_GM479516143.pdfIn PDF document text
    • http://ntweac.edu.hk/admin/ckfinder/userfiles/files/roblox-zone-free-robux_GM431946152.pdfIn PDF document text
    • http://ntweac.edu.hk/admin/ckfinder/userfiles/files/twitter-coin-master-free-spins_GM406889139.pdfIn PDF document text
    • http://ntweac.edu.hk/admin/ckfinder/userfiles/files/coin-master-hack-mod-apk-unlimited-spin-download_GM406889139.pdfIn PDF document text
    • http://ntweac.edu.hk/admin/ckfinder/userfiles/files/free-daily-spins-coin-master-2021_GM406889139.pdfIn PDF document text
    • http://ntweac.edu.hk/admin/ckfinder/userfiles/files/blox-world-free-robux_GM431946152.pdfIn PDF document text
    • http://ntweac.edu.hk/admin/ckfinder/userfiles/files/op-rewards-robux_GM431946152.pdfIn PDF document text
    • http://ntweac.edu.hk/admin/ckfinder/userfiles/files/mine-minecraft-games-for-free_GM479516143.pdfIn PDF document text
    • http://ntweac.edu.hk/admin/ckfinder/userfiles/files/free-robux-generator-no-survey-no-download-no-human-verification_GM431946152.pdfIn PDF document text
    • http://ntweac.edu.hk/admin/ckfinder/userfiles/files/free-spin-link-coin-master_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
stream_003_off00004b96.bin decompressed-pdf-stream PDF FlateDecoded stream at offset 0x4B96 25136 bytes
SHA-256: 5951e666197476726ac360eea28ceccb1ac5e5497666c017209c433675d1473e
font_01_sfnt_off000084bc.bin pdf-font-stream PDF embedded font (sfnt) at offset 0x84BC 18052 bytes
SHA-256: fae64eb33564783cbf84277a7ff47d82a2ae5ec1c1dc0520c64e362eeabcf4e5

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