Malicious PDF — malware analysis report

Static analysis result for SHA-256 a2773186908368f5…

MALICIOUS

PDF

36.2 KB Created: 2021-07-10 01:50:09 +07:00 Authoring application: wkhtmltopdf 0.12.6 (via Qt 4.8.7) First seen: 2021-09-16
MD5: efd8fdb989a2d0ddc432e58c666db664 SHA-1: 65e20a6f676c60bde2f424ad71bb1b820c05ef5e SHA-256: a2773186908368f5eb1dcbede6e8543d352defdc7e4155a2d05f9908a595f735
142 Risk Score

Malware Insights

MITRE ATT&CK
T1566.001 Spearphishing Attachment

This PDF document contains numerous embedded links, many of which are invisible and lead to CAPTCHA-themed lures. The primary goal appears to be a link farm designed to drive traffic to external sites, likely for ad revenue or to serve as a distribution point for further malicious content. The ML classifier strongly indicated maliciousness, and the PDF structure supports a link-luring attack pattern.

Machine Learning

  • Nyx PDF Classifier malicious score 0.9980

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.
  • Invisible PDF links to CAPTCHA-themed web lure high PDF_CAPTCHA_LINK_LURE
    PDF contains invisible clickable link annotations that point to a CAPTCHA/capcha-themed web path. This is a common phishing and ClickFix-style routing pattern: the PDF itself is inert, while the linked page performs the credential prompt or fake verification.
  • 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 http://netcdn.tw/app/431946152/free-robux-2021-game-hack PDF link annotation
    • https://laokhwanhos.com/ckfinder/userfiles/files/free-robux-no-verification-no-download-2021_GM431946152.pdfIn PDF document text
    • https://laokhwanhos.com/ckfinder/userfiles/files/minecraft-free-ios-2021_GM479516143.pdfIn PDF document text
    • https://laokhwanhos.com/ckfinder/userfiles/files/how-to-hack-roblox-accounts-2021-on-ipad_GM431946152.pdfIn PDF document text
    • https://laokhwanhos.com/ckfinder/userfiles/files/coin-mster-free_GM406889139.pdfIn PDF document text
    • https://laokhwanhos.com/ckfinder/userfiles/files/coin-master-free-foxy-food_GM406889139.pdfIn PDF document text
    • https://laokhwanhos.com/ckfinder/userfiles/files/how-to-get-minecraft-for-free-on-computer_GM479516143.pdfIn PDF document text
    • https://laokhwanhos.com/ckfinder/userfiles/files/coin-master-online-hack-download_GM406889139.pdfIn PDF document text
    • https://laokhwanhos.com/ckfinder/userfiles/files/8-free-robux_GM431946152.pdfIn PDF document text
    • https://laokhwanhos.com/ckfinder/userfiles/files/coin-master-daily-free-spins-link-download_GM406889139.pdfIn PDF document text
    • https://laokhwanhos.com/ckfinder/userfiles/files/free-robux-and-builders-club_GM431946152.pdfIn PDF document text
    • https://laokhwanhos.com/ckfinder/userfiles/files/free-robux-with-recapcha_GM431946152.pdfIn PDF document text
    • https://laokhwanhos.com/ckfinder/userfiles/files/coin-master-working-hack_GM406889139.pdfIn PDF document text
    • https://laokhwanhos.com/ckfinder/userfiles/files/free-robux-ad_GM431946152.pdfIn PDF document text
    • https://laokhwanhos.com/ckfinder/userfiles/files/vehicle-simulator-roblox-free_GM431946152.pdfIn PDF document text
    • https://laokhwanhos.com/ckfinder/userfiles/files/how-to-get-free-hair-on-roblox_GM431946152.pdfIn PDF document text
    • https://laokhwanhos.com/ckfinder/userfiles/files/how-to-get-free-coins-and-spins-on-coin-master_GM406889139.pdfIn PDF document text
    • https://laokhwanhos.com/ckfinder/userfiles/files/how-to-get-free-spins-on-coin-master-facebook_GM406889139.pdfIn PDF document text
    • https://laokhwanhos.com/ckfinder/userfiles/files/how-to-get-free-robux-no-human-verification-2021_GM431946152.pdfIn PDF document text
    • https://laokhwanhos.com/ckfinder/userfiles/files/free-robux-generator-no-installing-apps_GM431946152.pdfIn PDF document text
    • https://laokhwanhos.com/ckfinder/userfiles/files/coin-master-hacks-for-pet-food_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_off000035ca.bin pdf-font-stream PDF embedded font (sfnt) at offset 0x35CA 22608 bytes
SHA-256: 387bfcef2e65f5e9285fad4e2011bf20262a354c8d6ab92351784073f9e5a83c
font_01_sfnt_off00006872.bin pdf-font-stream PDF embedded font (sfnt) at offset 0x6872 19116 bytes
SHA-256: bd102244ffb40c6add567cd3640126a26b927334c4b0bdc73f6a542841550b4a

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