Malicious PDF — malware analysis report

Static analysis result for SHA-256 16143798cd8da731…

MALICIOUS

PDF

77.6 KB Created: 2021-06-14 02:13:56 +03:00 Authoring application: wkhtmltopdf 0.12.5 (via Qt 4.8.7) First seen: 2021-10-11
MD5: 45a7e170f8e531abba3d6f49492df495 SHA-1: 13b6c31eebcd4ff1e6a945855bd1ab1f8e892d5a SHA-256: 16143798cd8da7313940db0414d0530b017328e638a0d89b4aef61e9a1f5494d
156 Risk Score

Malware Insights

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

The PDF file was identified as malicious by ML classifiers and ClamAV, indicating a high likelihood of malicious intent. It contains numerous links to external resources, many of which point to compromised WordPress upload directories, suggesting it's part of a link farm designed to distribute malware or conduct phishing. The document body, though heavily obfuscated, contains metadata related to PDF merging and wkhtmltopdf, which is likely a lure to disguise the malicious nature of the links.

Machine Learning

  • Nyx PDF Classifier malicious score 0.9998

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://synerhu.ru/uplcv?utm_term=how+to+combine+two+pdfs+into+one PDF link annotation
    • https://www.die-umzugsfabrik.com/wp-content/plugins/formcraft/file-upload/server/content/files/1606f1e3488c28---pobemeporox.pdfIn PDF document text
    • http://canyonoaksmtg.com/~duckdi5/canyonoaksmtg.com/content/file/wafunijevonivevolofapinu.pdfIn PDF document text
    • http://alternativefitness.com.au/wp-content/plugins/formcraft/file-upload/server/content/files/160acb756c1dbe---givexepewixavodunan.pdfIn PDF document text
    • https://suhrsmad.dk/wp-content/plugins/formcraft/file-upload/server/content/files/1609ef078cfec2---75416290225.pdfIn PDF document text
    • https://www.bouwenaaneensterkwerkgeversmerk.nl/wp-content/plugins/formcraft/file-upload/server/content/files/1609bdcb2e3fb1---wafibinuwolutuzu.pdfIn PDF document text
    • https://aydin-elektrik.com/resimler/files/livivisuvonekezikipokofa.pdfIn PDF document text
    • https://www.westcountrystoves.co.uk/wp-content/plugins/super-forms/uploads/php/files/c469a672e0fa60da1ed954290d7c00d0/21488932375.pdfIn PDF document text
    • http://fortlauderdalelimorental.net/wp-content/plugins/formcraft/file-upload/server/content/files/16071325d10658---50388062630.pdfIn PDF document text
    • http://amctop.com/board_data/editor_img/file/202105101748.pdfIn PDF document text
    • https://dazzlin.co.uk/wp-content/plugins/super-forms/uploads/php/files/523ff543393db963be1606c2ab1b8de4/69889848251.pdfIn PDF document text
    • https://emauto.lv/index/images/up/file/62208737447.pdfIn PDF document text
    • http://anatolianlgs.com/userfiles/file/77182733382.pdfIn PDF document text
    • https://unique.global/wp-content/plugins/super-forms/uploads/php/files/dbf559dc04ecacf843465fbd31e896f7/46805625557.pdfIn PDF document text
    • https://sedefartphotography.com/resimler/files/64827451746.pdfIn PDF document text
    • http://www.birapart.com/wp-content/plugins/formcraft/file-upload/server/content/files/160850c528570e---daxozamizudeximoziz.pdfIn PDF document text
    • http://shengnabei.com/uploadfile/file/%5C/2021061111055063.pdfIn PDF document text
    • http://www.ascendercorp.com/In PDF document text
    • http://www.ascendercorp.com/typedesigners.htmlIn 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://scripts.sil.org/OFLIn PDF document text

Extracted artifacts 2

Files carved from inside the sample during analysis.

FilenameKindSourceSize
font_00_sfnt_off0000f189.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xF189 5156 bytes
SHA-256: fffc2681b74fe5b7805d01f3cfc00afe6229c4da3784694b6b56e3b4d140d465
font_01_sfnt_off00010317.bin pdf-font-stream PDF embedded font (sfnt) at offset 0x10317 11036 bytes
SHA-256: 7bcf5fb0a4b17a789e45662c451b1e181e23dd98fdfb24e32630954d9a054535