Malicious PDF — malware analysis report

Static analysis result for SHA-256 ef21ec1490648fff…

MALICIOUS

PDF

76.0 KB Created: 2021-09-10 14:25:39 +03:00 Authoring application: wkhtmltopdf 0.12.5 (via Qt 5.11.3) First seen: 2021-10-31
MD5: b1d4e90d9255091f9ec6120b3a53fd49 SHA-1: 1ab7262afd01caeb16cef1a6781e4b89814f51d5 SHA-256: ef21ec1490648ffff936c0dd33f7ba046f792aec83f81e50812baf44c119f2cb
156 Risk Score

Malware Insights

MITRE ATT&CK
T1566.001 Spearphishing Attachment

The file was identified as malicious by ML classifiers and ClamAV, specifically as a phishing trojan. Static analysis revealed it functions as a link farm, with numerous embedded URLs pointing to PDF files hosted on various domains, some of which appear to be compromised. The heuristic 'PDF_SEO_DISPOSABLE_LINK_FARM' strongly suggests this is an attempt to manipulate search engine rankings or distribute malicious content through a network of disposable links.

Machine Learning

  • Nyx PDF Classifier malicious score 0.9976

Heuristics 6

  • ClamAV: Pdf.Phishing.Trojan-d2528dad23a95d95-d2528dad23a95d95-10044376-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Pdf.Phishing.Trojan-d2528dad23a95d95-d2528dad23a95d95-10044376-0
  • 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://superpart.com/files/91712159962.pdf In PDF document text
    • http://cozycornerexpress.com/uploads/files/87350450158.pdfIn PDF document text
    • http://leap-egypt.com/wp-content/plugins/formcraft/file-upload/server/content/files/16132547a21bf5---demovupibufenusu.pdfIn PDF document text
    • http://autosoftware.company/autoresponders_images/files/fuvetejabuvaziximapugu.pdfIn PDF document text
    • http://tl-maskinfabrik.dk/userfiles/file/bolukozovojidapijepareze.pdfIn PDF document text
    • http://omatsuri.kr/data/userfiles/files/52182640472.pdfIn PDF document text
    • https://typeone.com.my/ckfinder/userfiles/files/wezitope.pdfIn PDF document text
    • http://nifaelectronics.com/userfiles/file/wukirukibimul.pdfIn PDF document text
    • https://gruntbudowa.pl/files/file/rowanifawudegupujuru.pdfIn PDF document text
    • http://mlsconsulting.net/cms/files/File/30996043751.pdfIn PDF document text
    • http://jandenzobv.com/image_uploads/file/biwerutatojid.pdfIn PDF document text
    • https://mtmnetwork.net/uploadEditor/files/rupifadisojoj.pdfIn PDF document text
    • http://bsp-plovdiv.org/ckfinder/userfiles/files/94801301338.pdfIn PDF document text
    • http://spartaksedlec.cz/spartaksedlec/userfiles/file/sotobisaxojije.pdfIn PDF document text
    • https://dutchfansitenetwork.nl/ckfinder/userfiles/files/66871333613.pdfIn PDF document text
    • http://hellnocancershow.com/wp-content/plugins/formcraft/file-upload/server/content/files/16132c6393dfac---lopuwidalatubesolakoja.pdfIn PDF document text
    • https://dongytueduc.com/wp-content/plugins/super-forms/uploads/php/files/5alkbaj6q5auta5r8pua99o7tr/50299877446.pdfIn PDF document text
    • https://faktxeber.com/resimler/files/sodagijetoraxapag.pdfIn PDF document text
    • https://masterjobintl.com/ckfinder/userfiles/files/vedijibutif.pdfIn PDF document text
    • http://giaydantuongphongngudep.com/images/news/file/sujilekoxod.pdfIn PDF document text
    • http://sterenstein.ru/userfiles/file/58843963655.pdfIn PDF document text
    • http://www.focitabor.hu/userfiles/file/tolovunovujiruvoxupufu.pdfIn PDF document text
    • http://qishuochem.com/siicea/userfiles/file/51388305234.pdfIn PDF document text
    • https://feedproxy.google.com/~r/1eyvgo/aqOO/~3/cv9VXjIrmdE/uplcv?utm_term=emuparadise+iso+psp+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_off0000c3f5.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xC3F5 18004 bytes
SHA-256: c7107a7d9194db4cefa2f58f44e57f041c5e65d1db5d13a1214ffbcfe8062a68
font_01_sfnt_off0000f273.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xF273 16792 bytes
SHA-256: 9d2294e344127da9ddc2b77d68b1576b6b78373885bc9da2859f180a98f2c1e1
font_02_sfnt_off00010a8a.bin pdf-font-stream PDF embedded font (sfnt) at offset 0x10A8A 10492 bytes
SHA-256: a71f704d5c28f637a8b305e5e56bc943fbddfb4a34247faecf72624bc6223e2e