Malicious PDF — malware analysis report

Static analysis result for SHA-256 51c81371b8169a92…

MALICIOUS

PDF

91.6 KB Created: 2021-08-05 19:35:02 +03:00 Authoring application: wkhtmltopdf 0.12.5 (via Qt 5.11.3) First seen: 2021-10-11
MD5: c882b7c2284d8704c4a274c7fa2bff45 SHA-1: 58816e4f10685eec6cb5751ba58019c85bcec34a SHA-256: 51c81371b8169a927926d6ac27f462a1d6ea2932bfab40d068161d6bea04f11a
156 Risk Score

Malware Insights

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

The PDF contains numerous embedded URLs, many of which point to domains flagged as link farms or potentially compromised CMS uploads. The ML classifier and ClamAV detection strongly indicate malicious intent, likely related to phishing or SEO spam. No scripts were extracted, and the document body was unreadable, so the attack pattern is inferred from the URL analysis and heuristic firings.

Machine Learning

  • Nyx PDF Classifier malicious score 0.9970

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://namlongadc.com/uploads/news/files/zumakixuf.pdf In PDF document text
    • http://straps.by/ckfinder/userfiles/files/63706163617.pdfIn PDF document text
    • https://technok.cz/wp-content/plugins/super-forms/uploads/php/files/6b0f9d9af15fb68dfb6391b93afb6c47/81465175662.pdfIn PDF document text
    • http://www.kissdocs.com.au/wp-content/plugins/formcraft/file-upload/server/content/files/1607eb774296a0---88445592563.pdfIn PDF document text
    • http://www.sm.ac.th/ckfinder/userfiles/files/vadele.pdfIn PDF document text
    • http://brmxn.com/userfiles/file/20210722142941_u6zbmi.pdfIn PDF document text
    • http://test.uebersetzungen-nesselberger.de/wp-content/plugins/formcraft/file-upload/server/content/files/1608922b434e28---29213593024.pdfIn PDF document text
    • http://ackerviewguesthouse.com/userfiles/file/15007138380.pdfIn PDF document text
    • http://tpdw.pl/userfiles/file/suxazenileg.pdfIn PDF document text
    • https://miamiuniquelimo.com/wp-content/plugins/formcraft/file-upload/server/content/files/160b2317f36427---30785299050.pdfIn PDF document text
    • http://antifftech.com/uploadfile/file///2021060516120890.pdfIn PDF document text
    • https://lokmangal.co.in/wp-content/plugins/super-forms/uploads/php/files/4672742c679e4d50a8051e4f8a4e5ab8/94548470045.pdfIn PDF document text
    • http://xn--9w3b270a7kf.kr/ckfinder/userfiles/files/wuzikozuduk.pdfIn PDF document text
    • http://dirabrealtors.com/wp-content/plugins/formcraft/file-upload/server/content/files/160c9558963dc0---87824202325.pdfIn PDF document text
    • https://zazilha.com.mx/wp-content/plugins/super-forms/uploads/php/files/afed69c0255cd688303b40178493f0db/68066405750.pdfIn PDF document text
    • http://villa-carlshorst.de/sites/default/files/file/xenugipipeguzuj.pdfIn PDF document text
    • http://3handseg.com/wp-content/plugins/formcraft/file-upload/server/content/files/1607e973aeb43a---41228628456.pdfIn PDF document text
    • http://superazs.ru/images/news/file/90527674386.pdfIn PDF document text
    • https://inoxquochoang.com/app/webroot/files/images/pages/files/juxutipefaxevorukiled.pdfIn PDF document text
    • https://humble-brag.com/wp-content/plugins/super-forms/uploads/php/files/510s6mfacitt43q2dd0e1nlmdo/gipatulek.pdfIn PDF document text
    • https://bohemiamaestro.com/webpagebuilder/ckfinder/userfiles/files/dewubun.pdfIn PDF document text
    • http://aimecostruzioni.it/userfiles/files/25068751894.pdfIn PDF document text
    • https://humble-brag.com/wp-content/plugins/super-forms/uploads/php/files/n8kskefa1uivupvcstaph3tt8n/fivurevotazavixupugupoz.pdfIn PDF document text
    • https://engravestone.com/wp-content/plugins/formcraft/file-upload/server/content/files/1609662927d228---juvujogopopufotevenerax.pdfIn PDF document text
    • https://feedproxy.google.com/~r/Uplcv/~3/S30rS-6n6vg/uplcv?utm_term=harry+potter+and+the+goblet+of+fire+chapter+13+summaryPDF 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_off0001016d.bin pdf-font-stream PDF embedded font (sfnt) at offset 0x1016D 11636 bytes
SHA-256: 1679e4f141a3c4a85cbb708ff1a419a14e0802c84a55458b7a1189adc395a126
font_01_sfnt_off00011c7f.bin pdf-font-stream PDF embedded font (sfnt) at offset 0x11C7F 16792 bytes
SHA-256: 9d2294e344127da9ddc2b77d68b1576b6b78373885bc9da2859f180a98f2c1e1
font_02_sfnt_off00013491.bin pdf-font-stream PDF embedded font (sfnt) at offset 0x13491 16816 bytes
SHA-256: 1be605294b537831243fbd63b61f7cbad1d8da393c385e9ead5ac23d1b8860aa