Malicious PDF — malware analysis report

Static analysis result for SHA-256 21137b786dfc01cc…

MALICIOUS

PDF

70.1 KB Created: 2021-09-07 16:15:06 +03:00 Authoring application: wkhtmltopdf 0.12.5 (via Qt 5.11.3) First seen: 2021-10-11
MD5: 4203b2b961bbf597961d4fa35240fbd1 SHA-1: 156055f76ee5d98231f4575a01844dc28c88f395 SHA-256: 21137b786dfc01ccbdc38bbca4c8a5930b9f202d2a7d5bc2f75382ec1de5de36
156 Risk Score

Malware Insights

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

The PDF file was identified as malicious by ML classifiers and ClamAV, specifically flagged as a phishing trojan. Heuristics indicate it functions as a link farm, with numerous embedded URLs pointing to compromised WordPress uploads and other potentially disposable hosting domains. The document body is heavily obfuscated and appears to be non-readable content generated by wkhtmltopdf, suggesting the primary purpose is to host these links rather than convey information.

Machine Learning

  • Nyx PDF Classifier malicious score 0.9956

Heuristics 6

  • ClamAV: Pdf.Phishing.Trojan-d2568dad23a94d95-d2568dad23a94d95-10044375-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Pdf.Phishing.Trojan-d2568dad23a94d95-d2568dad23a94d95-10044375-0
  • 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 http://patroha.hu/file/32526760960.pdf In PDF document text
    • http://geology.ie/wp-content/plugins/formcraft/file-upload/server/content/files/160ac24b90ab39---fufapirakakajikud.pdfIn PDF document text
    • http://ezibra.pl/upload//file/kolalolu.pdfIn PDF document text
    • http://blbr365.com/userfiles/file/1622890975.pdfIn PDF document text
    • http://bocghebinhduong.com/media/ftp/file/forisaselojajo.pdfIn PDF document text
    • http://boeschfamilytravels.com/clients/43210/File/nigigowaxipafutorero.pdfIn PDF document text
    • http://chronicles.ae/userfiles/files/15163346780.pdfIn PDF document text
    • http://www.yourhealthyourchoice.org/wp-content/plugins/formcraft/file-upload/server/content/files/160abaac3097be---81992711681.pdfIn PDF document text
    • https://www.beachesbrewing.com/wp-content/plugins/super-forms/uploads/php/files/3cb41fbebfc7c80f92939ddc1b7ff506/mewivuluvezugogatikexapu.pdfIn PDF document text
    • http://kompletucetnictvi.cz/files/file/rigevugabek.pdfIn PDF document text
    • http://belean.pl/userfiles/file/wagikunisepa.pdfIn PDF document text
    • https://agatanorek.com/files/file/zojupebegilarunejuseweve.pdfIn PDF document text
    • http://binhchuachay.info/Images_upload/files/84126315674.pdfIn PDF document text
    • https://cihangirhotel.com/upload/ckfinder/files/nawut.pdfIn PDF document text
    • https://nepalipublisher.com/ckfinder/userfiles/files/56668733875.pdfIn PDF document text
    • http://kfnmsz.com/upfolder/e/files/20210706184728.pdfIn PDF document text
    • https://www.hontoys.com.au/wp-content/plugins/super-forms/uploads/php/files/u2o21ck284bei33jmktipedguf/13594935963.pdfIn PDF document text
    • https://watertorens.nl/userfiles/file/51676182225.pdfIn PDF document text
    • https://ski-experience-japan.com/images/blog//file/51810861040.pdfIn PDF document text
    • http://www.1000ena.com/wp-content/plugins/formcraft/file-upload/server/content/files/160b1a51ba27d4---88123200249.pdfIn PDF document text
    • https://beaufortbond.com/wp-content/plugins/super-forms/uploads/php/files/132395f5c86a3eedbf1e55a5c3995fdf/savuzo.pdfIn PDF document text
    • https://avenirpourtous.fr/wp-content/plugins/formcraft/file-upload/server/content/files/16080dd5a429de---tifiz.pdfIn PDF document text
    • http://3e3i.com/UserFiles/file///71416440173.pdfIn PDF document text
    • https://feedproxy.google.com/~r/Uplcv/~3/S30rS-6n6vg/uplcv?utm_term=logotherapy+worksheets+pdfPDF 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_off0000b302.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xB302 15488 bytes
SHA-256: 0d663e4861874aab9ced122e78ec2656c4c8a5a455fb027d80221453984785ca
font_01_sfnt_off0000d9ff.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xD9FF 10784 bytes
SHA-256: 5b5c55ccef020d9825b8a053613f3d1d4d42974265d5611a4a5e959a139bed95
font_02_sfnt_off0000f2e8.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xF2E8 16792 bytes
SHA-256: 9d2294e344127da9ddc2b77d68b1576b6b78373885bc9da2859f180a98f2c1e1

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