Malicious PDF — malware analysis report

Static analysis result for SHA-256 440881cfd41b6154…

MALICIOUS

PDF

71.6 KB Created: 2021-09-05 23:05:03 +03:00 Authoring application: wkhtmltopdf 0.12.5 (via Qt 5.11.3) First seen: 2021-10-26
MD5: 4f81c5ebd34f009ba4ef1dcea8cf4ea4 SHA-1: 4fc5dfd3341c0109399a0f2b5be3e9ca94504da8 SHA-256: 440881cfd41b61540d5398004dc74ac13598c09c55c62eaa52bb3c2d899e5ec4
156 Risk Score

Malware Insights

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

The file was detected as a malicious PDF by ClamAV and an ML classifier, indicating a high likelihood of malicious intent. Heuristics reveal it functions as a link farm, directing users to multiple potentially compromised websites, including a WordPress upload storage. The document body is heavily obfuscated and appears to be generated by wkhtmltopdf, suggesting it's not intended for human readability but rather to host links.

Machine Learning

  • Nyx PDF Classifier malicious score 0.9982

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 https://cructi.ru/uplcv?utm_term=physical+science+concepts+in+action+book+pdf PDF link annotation
    • http://preserveproperties.com/userfiles/files/54346267689.pdfIn PDF document text
    • http://sun-tes.ru/files/file/89698967190.pdfIn PDF document text
    • http://sk-uralstroy.ru/uploads/files/dokexu.pdfIn PDF document text
    • http://stadion-zarya.ru/ckfinder/userfiles/files/89732120757.pdfIn PDF document text
    • http://mgtofubbq.com/uploads/files/tukumutiviv.pdfIn PDF document text
    • https://mygoaltv.org/ipp/images/uploads/files/doduregijujunofoxefulek.pdfIn PDF document text
    • http://autoshiftbid.com/fckeditor/userfiles/file/jitamojaleka.pdfIn PDF document text
    • http://stlnsk.ru/uploads/file/18276267693.pdfIn PDF document text
    • http://jedzenie365.pl/ckfinder/userfiles/files/57421286166.pdfIn PDF document text
    • https://www.amiunaorchestra.ro/wp-content/plugins/formcraft/file-upload/server/content/files/1609e7c14188ad---46882662925.pdfIn PDF document text
    • http://apsencollege.org/test/fckeditor/file/pefop.pdfIn PDF document text
    • http://www.restorationservice.ca/wp-content/plugins/formcraft/file-upload/server/content/files/1608e71ad8a069---berezowavaxe.pdfIn PDF document text
    • https://tunhuaduytan.com/upload/userfiles/files/5061430612.pdfIn PDF document text
    • https://www.businesswatchguardingservices.co.uk/wp-content/plugins/super-forms/uploads/php/files/mhodhi8ga56v5tbcbtqbp6qq53/kufikekujalo.pdfIn PDF document text
    • https://humantouchtranslations.com/wp-content/plugins/formcraft/file-upload/server/content/files/1/1608260c61ec16---zisox.pdfIn PDF document text
    • http://global-poseg.com/wp-content/plugins/formcraft/file-upload/server/content/files/16095fbb5d8b61---25729426364.pdfIn PDF document text
    • http://www.myhhsi.com/wp-content/plugins/super-forms/uploads/php/files/161b8002c994df9ea5116ca512915a14/23773145307.pdfIn PDF document text
    • https://olgapopovaphoto.com/wp-content/plugins/super-forms/uploads/php/files/749c2a18b8841466364a77d6cb7363c2/48879342646.pdfIn PDF document text
    • http://psychologyforeverybody.com/ckfinder/userfiles/files/80947402931.pdfIn PDF document text
    • https://moyaexpresss.com/ckfinder/userfiles/files/dolodu.pdfIn PDF document text
    • http://jucal.es/images/file/bekofiridoliga.pdfIn PDF document text
    • http://www.icodar.com/wp-content/plugins/formcraft/file-upload/server/content/files/1607ff37a8ce49---nakemasegufeti.pdfIn PDF document text
    • 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_off0000b679.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xB679 10964 bytes
SHA-256: 3a7f37ff9e5e559bc2aa3a4a8e18f9e56777020bfd2780a859c0ea93b0dbcf43
font_01_sfnt_off0000cfa7.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xCFA7 15932 bytes
SHA-256: af427cf38d986397ec48555df90d6344358ccf7063c620cf0e107e59b8ae9d08
font_02_sfnt_off0000f884.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xF884 16792 bytes
SHA-256: 9d2294e344127da9ddc2b77d68b1576b6b78373885bc9da2859f180a98f2c1e1

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