Malicious PDF — malware analysis report

Static analysis result for SHA-256 21f3b357355b8c91…

MALICIOUS

PDF

79.6 KB Created: 2021-08-20 05:42:49 +03:00 Authoring application: wkhtmltopdf 0.12.5 (via Qt 5.11.3) First seen: 2021-10-14
MD5: 6e5f94d13eed8acb69cd26a06959bca6 SHA-1: 0dc115a35cbe2173e4b90f706d013dd944b7bd18 SHA-256: 21f3b357355b8c9158959099c19ec0d909dfac1bb67ea17ff889cb91caf6d23f
156 Risk Score

Malware Insights

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

The PDF file was flagged by multiple heuristics and a machine learning classifier as malicious, with ClamAV identifying it as Pdf.Phishing.Trojan. The numerous embedded URLs point to compromised WordPress sites, suggesting a link farm designed to lure users to malicious content. The document body was unreadable, but the overall structure and URL analysis strongly indicate a phishing or malware distribution attempt.

Machine Learning

  • Nyx PDF Classifier malicious score 0.9978

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=what+is+the+ideal+light+intensity+for+photosynthesis+percentage PDF link annotation
    • https://www.ezhealthcheck.com/wp-content/plugins/super-forms/uploads/php/files/arpacmj2oe3ir45oc7o0c8ii30/57445257007.pdfIn PDF document text
    • https://agilitynd.com/wp-content/plugins/super-forms/uploads/php/files/bcb9891520a21ff87f952cc6d1c23651/vapiwavutinotenowevu.pdfIn PDF document text
    • https://masterok-kovka.ru/wp-content/plugins/super-forms/uploads/php/files/2747ae03e253f37119ed066cb62b33af/92465667422.pdfIn PDF document text
    • https://www.kadinlarsitesi.org/wp-content/plugins/formcraft/file-upload/server/content/files/160c29d40bd086---63728889812.pdfIn PDF document text
    • https://akconta.com/uploads/files/85131236607.pdfIn PDF document text
    • http://geasit.it/userfiles/files/73551434281.pdfIn PDF document text
    • https://lakeshoresmilesdentistry.com/wp-content/plugins/super-forms/uploads/php/files/ml1phq1mdteq5g0o1n0qn41lk1/83464759789.pdfIn PDF document text
    • http://grupomarsamo.com/wp-content/plugins/formcraft/file-upload/server/content/files/16073e18962053---rosuvudofonuxejar.pdfIn PDF document text
    • https://boucherienabli.com/uploads/FCK_files/file/rafejemubunidodazulatano.pdfIn PDF document text
    • http://graficaeformazione.it/userfiles/file/28359737886.pdfIn PDF document text
    • http://jcon-aps.dk/userfiles/file/pejibisimulesesojasejovur.pdfIn PDF document text
    • https://www.darrellstuckey.com/wp-content/plugins/formcraft/file-upload/server/content/files/160e819d4758be---23878294952.pdfIn PDF document text
    • http://gulfcoolcontracting.com/uploads/userfiles/file/file/dadosedulasewemekexojuwi.pdfIn PDF document text
    • https://bikinibody.be/wp-content/plugins/super-forms/uploads/php/files/1bils8clgc6c4lghlgnrjrunn0/xezelige.pdfIn PDF document text
    • https://alcc.vn/wp-content/plugins/super-forms/uploads/php/files/2ar6dm8tvliv0in8eaoepve5sn/wiboxekaxoruf.pdfIn PDF document text
    • http://www.orarestauratorisaf.it/wp-content/plugins/formcraft/file-upload/server/content/files/160c971cd049c1---8918946789.pdfIn PDF document text
    • http://www.dnevi-sekretarjev.eu/wp-content/plugins/formcraft/file-upload/server/content/files/160bcc367b63df---wurejalejadelek.pdfIn PDF document text
    • https://tsegypt.com/file/14788155707.pdfIn PDF document text
    • http://alexandersorokolaw.com/customer/3/d/9/3d947ad6ce2568d98b832ccf5548371bFile/30631381797.pdfIn PDF document text
    • http://dyglas.com/userData/board/file/pimimad.pdfIn PDF document text
    • http://www.oschouston.com/osc/wp-content/plugins/formcraft/file-upload/server/content/files/160f23df8ecf6c---nusawoduti.pdfIn PDF document text
    • https://www.gullyracing.it/admin/ckfinder/userfiles/files/sokaduriri.pdfIn PDF document text
    • http://yokohama-model.com/userfiles/files/6927774420.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_off0000d23e.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xD23E 11004 bytes
SHA-256: 1991e59441d7e78b6a81a51e6c89340344198f747d7720c49a82fd7809fc0d3c
font_01_sfnt_off0000eb95.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xEB95 16492 bytes
SHA-256: 00e2f0647b162744c5866fcd6a86e8e1dc345a570c76f624eb67588e423be4d1
font_02_sfnt_off00011649.bin pdf-font-stream PDF embedded font (sfnt) at offset 0x11649 16792 bytes
SHA-256: 9d2294e344127da9ddc2b77d68b1576b6b78373885bc9da2859f180a98f2c1e1