Malicious PDF — malware analysis report

Static analysis result for SHA-256 844539db26fa509b…

MALICIOUS

PDF

85.0 KB Created: 2021-09-02 04:16:20 +03:00 Authoring application: wkhtmltopdf 0.12.5 (via Qt 5.11.3) First seen: 2021-10-23
MD5: 085b6f374bf65e9b8962c7438747e790 SHA-1: 3ed466a8469c27ee48c551a28ce2f23167ae7391 SHA-256: 844539db26fa509bd28b71a2a1f1a6f2d51accfeb9cd35bf088e4485345b3d33
172 Risk Score

Malware Insights

MITRE ATT&CK
T1566.001 Spearphishing Attachment

The sample is a PDF document containing embedded JavaScript and a significant number of external URIs. Several heuristics indicate this PDF is part of a link farm, with many links pointing to compromised WordPress uploads and disposable hosting. The ML classifier and ClamAV detection strongly suggest malicious intent, likely related to phishing or malware delivery via these links.

Machine Learning

  • Nyx PDF Classifier malicious score 0.9994

Heuristics 8

  • 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.
  • Embedded JS stream low PDF_JS
    PDF references a /JS stream. Generic JavaScript is common in benign forms; specific dangerous APIs are scored by separate rules.
  • Urgency / deadline lure low SE_URGENCY_LURE
    Document contains urgency or deadline language ('account will be terminated', 'action required within 24 hours', etc.) — useful context, but low-signal without other findings
  • 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://wastran.ru/uplcv?utm_term=recent+advances+in+obstetrics+and+gynaecology+27+pdf PDF link annotation
    • https://vietnamairlinescorp.org/js/ckfinder/userfiles/files/wataweluropiranuwaral.pdfIn PDF document text
    • http://nomorecpapmachine.com/userfiles/files/52700895513.pdfIn PDF document text
    • http://mexvp.com/ckfinder/userfiles/files/mozizu.pdfIn PDF document text
    • http://impex-italia.it/userfiles/files/91262000579.pdfIn PDF document text
    • http://brighterhealthcare.co.uk/wp-content/plugins/super-forms/uploads/php/files/i0fcfu8hs11jeaur4r6glpptbb/61328570252.pdfIn PDF document text
    • http://metrocars.london/survey/userfiles/files/32266769810.pdfIn PDF document text
    • http://boletin.alicantehosteleria.com/lib/ckfinder/userfiles/files/7360455837.pdfIn PDF document text
    • https://serini-cloud.pl/uploads/editor/file/41672324332.pdfIn PDF document text
    • http://akicgiyim.com/userfiles/file/segiluzanune.pdfIn PDF document text
    • http://aeskulap24h.com/wp-content/plugins/formcraft/file-upload/server/content/files/160a8dccaa3ca3---gaporawivowogonami.pdfIn PDF document text
    • https://www.democratum.com/wp-content/plugins/super-forms/uploads/php/files/2b5a0c711e74cdf23f4d5d2b2db02341/67228799225.pdfIn PDF document text
    • http://busanpc1.com/upload/fckeditor/file/87100918466.pdfIn PDF document text
    • http://mitroc.com/userfiles/file/salufalojipeputivatamizid.pdfIn PDF document text
    • https://master.plus/wp-content/plugins/super-forms/uploads/php/files/d8a82cd9b7f42ade95a03dc8f7a5e805/5573596854.pdfIn PDF document text
    • https://rmissio.pl/wp-content/plugins/formcraft/file-upload/server/content/files/16098c01da7b38---ruwifab.pdfIn PDF document text
    • http://www.derbysignandgraphics.com/uploads/file/vexofedotexenubimovojuriw.pdfIn PDF document text
    • http://reiki-roots.co.uk/wp-content/plugins/formcraft/file-upload/server/content/files/160a251fd217e8---sajoponagudodudawulugorej.pdfIn PDF document text
    • http://locthanhroyal.com/upload/files/jurivapilenuganonele.pdfIn PDF document text
    • http://lbs.ac.at/wp-content/plugins/super-forms/uploads/php/files/4ojh78rce2121js5rclv71o0j3/tepovefibudafi.pdfIn PDF document text
    • https://fwstc.in/userfiles/file/jadafatonuneziri.pdfIn PDF document text
    • http://corising.info/sa_upload/userfiles/file/20210807083759.pdfIn PDF document text
    • http://tj-1970-50yr.com/clients/e/e8/e8fccb6fb94f20b6ca4375945b3939e1/File/65634165085.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_off0000e385.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xE385 18240 bytes
SHA-256: 30895ef80204a0d21f9fff10b5c9f60d4fe3f88c36566b995cdf1cad323bc19b
font_01_sfnt_off000112d6.bin pdf-font-stream PDF embedded font (sfnt) at offset 0x112D6 16792 bytes
SHA-256: 9d2294e344127da9ddc2b77d68b1576b6b78373885bc9da2859f180a98f2c1e1
font_02_sfnt_off00012aed.bin pdf-font-stream PDF embedded font (sfnt) at offset 0x12AED 11332 bytes
SHA-256: e7f730160298fd885b0570d0bb5bbef6338ee346205c6685cc6791ae4c2ae53c

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