Malicious PDF — malware analysis report

Static analysis result for SHA-256 21d3b84e05d49178…

MALICIOUS

PDF

45.1 KB Created: 2021-06-04 00:02:12 +07:00 Authoring application: wkhtmltopdf 0.12.6 (via Qt 4.8.7) First seen: 2021-09-27
MD5: 28d63cd74cd44f15690e182f065cbc1f SHA-1: 643d6c3781561b63f6f621a4cae1d2176c960c4e SHA-256: 21d3b84e05d49178a749ddfa498082d6fd8c0e9b48577dc0dd97a53ced2bb2a5
142 Risk Score

Malware Insights

MITRE ATT&CK
T1566.001 Spearphishing Attachment T1204.002 Malicious Link

The PDF document contains a fake CAPTCHA lure, designed to trick users into interacting with malicious links. It also exhibits characteristics of a link farm, with numerous external links pointing to potentially malicious content. The ML classifier strongly indicates maliciousness, supporting the observed attack pattern.

Machine Learning

  • Nyx PDF Classifier malicious score 0.9865

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.online/app/431946152/free-robux-giveaway-game-hack PDF link annotation
    • http://library.umla.ac.id/repository/free-minecraft-client_GM479516143.pdfIn PDF document text
    • http://library.umla.ac.id//repository/minecraft-servers-that-allow-hacks_GM479516143.pdfIn PDF document text
    • http://library.umla.ac.id/repository/get-free-spins-on-coin-master_GM406889139.pdfIn PDF document text
    • http://library.umla.ac.id/repository/pubg-uc-or-bp_GM1330123889.pdfIn PDF document text
    • http://library.umla.ac.id/repository/coin-master-free-redeem-code_GM406889139.pdfIn PDF document text
    • http://library.umla.ac.id//repository/cheat-codes-for-coin-master_GM406889139.pdfIn PDF document text
    • http://library.umla.ac.id/repository/robux-hack-2021_GM431946152.pdfIn PDF document text
    • http://library.umla.ac.id//repository/free-minecraft-realms-to-join_GM479516143.pdfIn PDF document text
    • http://library.umla.ac.id/repository/coin-master-hack-2021-android_GM406889139.pdfIn PDF document text
    • http://library.umla.ac.id//repository/coin-master-free-coin-hack_GM406889139.pdfIn PDF document text
    • http://library.umla.ac.id/repository/coin-master-hack-version-download-2021-android_GM406889139.pdfIn PDF document text
    • http://library.umla.ac.id/repository/coin-master-hack-without-verification-2021_GM406889139.pdfIn PDF document text
    • http://library.umla.ac.id//repository/free-minecraft-texture-packs-java_GM479516143.pdfIn PDF document text
    • http://library.umla.ac.id/repository/free-coins-spins-on-coin-master_GM406889139.pdfIn PDF document text
    • http://library.umla.ac.id/repository/coin-master-free-spin-whatsapp-group_GM406889139.pdfIn PDF document text
    • http://library.umla.ac.id/repository/cpbildco-robux_GM431946152.pdfIn PDF document text
    • http://library.umla.ac.id/repository/how-to-get-roblox-credit-for-free_GM431946152.pdfIn PDF document text
    • http://library.umla.ac.id//repository/how-you-get-free-robux_GM431946152.pdfIn PDF document text
    • http://library.umla.ac.id/repository/how-to-get-creative-mode-in-minecraft-server-hack_GM479516143.pdfIn PDF document text
    • http://library.umla.ac.id/repository/how-to-earn-free-robux_GM431946152.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_004_off00005341.bin decompressed-pdf-stream PDF FlateDecoded stream at offset 0x5341 24572 bytes
SHA-256: 0995c976fa1751a67558807e0337929abd954771f7bd62a065b3966e8287b5d5
font_01_sfnt_off00008bf9.bin pdf-font-stream PDF embedded font (sfnt) at offset 0x8BF9 18820 bytes
SHA-256: a907981f6338d23acda294c558170907db38f399f16fdb2ca0bc536a0b707f6d

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