Malicious PDF — malware analysis report

Static analysis result for SHA-256 8c81841cec7cdb08…

MALICIOUS

PDF

86.6 KB Created: 2021-09-11 04:45:41 +03:00 Authoring application: wkhtmltopdf 0.12.5 (via Qt 5.11.3) First seen: 2021-10-11
MD5: 33d737f8151a4d260d2922d4388d9f7a SHA-1: 993f7050ba7d35092b823ea738752b594d772373 SHA-256: 8c81841cec7cdb08a2f813073d6a790d42da8c52cdc3d0040cfd40b6c0ad096a
96 Risk Score

Malware Insights

MITRE ATT&CK
T1566.001 Spearphishing Attachment

The PDF file contains a significant number of embedded URLs, many of which point to compromised CMS uploads and disposable hosting, indicating a link farm designed to redirect users. The ML classifier also flagged this PDF as malicious with high confidence. While no scripts were explicitly extracted, the nature of the embedded links suggests a phishing or redirection attempt, likely delivered as a spearphishing attachment.

Machine Learning

  • Nyx PDF Classifier malicious score 0.9942

Heuristics 5

  • PDF link farm points to compromised-WordPress upload storage medium PDF_COMPROMISED_CMS_UPLOAD_LINK_FARM
    PDF contains multiple clickable links, across many distinct hosts, whose targets are random-slug files parked in the upload directories of vulnerable WordPress form plugins (FormCraft, Super Forms). This is the hallmark of the 'free document/template' SEO phishing PDF family, which ranks for search queries and routes users into payload/redirect chains hosted on compromised sites. The PDF itself carries no exploit — the risk is the linked destinations.
  • Small PDF is a non-clustered link farm on disposable hosting medium PDF_SEO_DISPOSABLE_LINK_FARM
    Small PDF contains many clickable external PDF links spread thin across many distinct hosts (no single dominant host), corroborated by a utm_term SEO-redirector link and/or links parked on free/disposable content hosts. This is the 'free document/template' SEO phishing PDF family, which ranks for search queries and routes users into payload/redirect chains, rather than a normal document citation pattern. The PDF itself carries no exploit — the risk is the linked destinations.
  • External URI info PDF_URI
    PDF contains an external URL action
  • Object number defined twice with different bodies info PDF_DUPLICATE_OBJ_BODY_INCREMENTAL
    The same indirect object (N G) is defined more than once with different body bytes. First-wins and last-wins readers will resolve different content, which is a parser-confusion shape used by targeted PDFs. Body-only differences are common in benign incremental updates, so severity is raised only when the duplicate carries active content.
  • 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://fishuntpesca.it/file/85687346591.pdf In PDF document text
    • http://xn--42cfa4ewb0a0b3fwh.com/imageupload/files/14497192338.pdfIn PDF document text
    • http://bscsaoner.in/ckfinder/userfiles/files/dezitexuxidikelovobip.pdfIn PDF document text
    • https://vinniescustoms.com/userfiles/files/jaxenevugasibezejono.pdfIn PDF document text
    • http://krindustria.com.br/site/wp-content/plugins/formcraft/file-upload/server/content/files/161363cec53b3c---97163065679.pdfIn PDF document text
    • http://wordtmann.beckbauer.eu/ckfinder/userfiles/files/vepufifed.pdfIn PDF document text
    • https://varida-tech.com/ckfinder/userfiles/files/vexevebe.pdfIn PDF document text
    • http://www.rec39.ru/wp-content/plugins/super-forms/uploads/php/files/e5632d5b9ed8611036e299094b59d3ab/72113993830.pdfIn PDF document text
    • http://triumphtoday.org/wp-content/plugins/formcraft/file-upload/server/content/files/161346d5a6efcd---33702440363.pdfIn PDF document text
    • http://ahrestygz.com/userfiles/files/20210901_101110.pdfIn PDF document text
    • https://encouragingmath.com/wp-content/plugins/super-forms/uploads/php/files/21ba5c285bca6fd6e4fe302eabf2bdc1/nifuwobutubil.pdfIn PDF document text
    • http://www.introspekta.si/ckfinder/ckeditor_uploaded_files/files/75324122676.pdfIn PDF document text
    • http://flagrant-desir.com/userfiles/file/72766617684.pdfIn PDF document text
    • https://digireg.org/upload/96588009746.pdfIn PDF document text
    • http://aokisuper.com/ckfinder/userfiles/files/28177164684.pdfIn PDF document text
    • https://petribax.nl/userfiles/file/23062311629.pdfIn PDF document text
    • https://www.andeanskyline.com/wp-content/plugins/formcraft/file-upload/server/content/files/1613ac79425276---gowise.pdfIn PDF document text
    • http://xn--80aafjbawrcdgsodbdciig4a5v.xn--p1ai/pict/file/47938452033.pdfIn PDF document text
    • https://speakingparrot.com/upload/ckfinder/files/53265253118.pdfIn PDF document text
    • https://pernambucoimortal.com/imagens/files/705152878.pdfIn PDF document text
    • https://o-dance.com/upload/files/64579629668.pdfIn PDF document text
    • https://mimpishiodua.com/contents/files/84642878638.pdfIn PDF document text
    • https://binhruamuinanobac.com/wp-content/plugins/super-forms/uploads/php/files/rh9f7isu103k00r0oeb9gk1tm4/59799759302.pdfIn PDF document text
    • http://xn----7sbakif2a3azdub.xn--p1ai/admin/ckfinder/userfiles/files/maxamuvijusavuletizo.pdfIn PDF document text
    • http://twgo8.com/uploads/base/files/202109050832229033.pdfIn PDF document text
    • https://feedproxy.google.com/~r/1eyvgo/aqOO/~3/3vuEKuznOb8/uplcv?utm_term=best+free+music+streaming+apps+for+androidPDF link annotation
    • http://www.w3.org/1999/02/22-rdf-syntax-ns#In PDF document text
    • http://purl.org/dc/elements/1.1/In PDF document text
    • http://ns.adobe.com/pdf/1.3/In PDF document text
    • http://ns.adobe.com/xap/1.0/In PDF document text
    • http://ns.adobe.com/xap/1.0/mm/In PDF document text
    • http://ns.adobe.com/xap/1.0/rights/In PDF document text
    • http://dejavu.sourceforge.netIn PDF document text
    • http://dejavu.sourceforge.net/wiki/index.php/LicenseIn PDF document text

Extracted artifacts 3

Files carved from inside the sample during analysis.

FilenameKindSourceSize
font_00_sfnt_off0000ee32.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xEE32 17472 bytes
SHA-256: 6554434e6b7ce840805e07317b83f05f25f6da1ce4942619b66626c80299be61
font_01_sfnt_off00011af9.bin pdf-font-stream PDF embedded font (sfnt) at offset 0x11AF9 16792 bytes
SHA-256: 9d2294e344127da9ddc2b77d68b1576b6b78373885bc9da2859f180a98f2c1e1
font_02_sfnt_off00013310.bin pdf-font-stream PDF embedded font (sfnt) at offset 0x13310 11072 bytes
SHA-256: 6348bac33e15ba2791d6ecd9bc99ef11b2a6b64d5322aa3a3a13580e337d571b