Malicious PDF — malware analysis report

Static analysis result for SHA-256 f39baa12c25c9419…

MALICIOUS

PDF

81.8 KB Created: 2021-09-15 14:08:58 +03:00 Authoring application: wkhtmltopdf 0.12.5 (via Qt 5.11.3) First seen: 2021-10-12
MD5: 4c5e9fc95a012a5649b955d475cd026b SHA-1: 22661e38003a072e4c2f9002a0561e42f9d0ad63 SHA-256: f39baa12c25c94194beaeadd2b5367472285731520825777dc5b4fd150421dda
156 Risk Score

Malware Insights

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

The sample is a PDF file identified as malicious by ML classifiers and ClamAV, specifically flagged as a phishing trojan. It functions as a link farm, with numerous embedded URLs pointing to external sites, some hosted on compromised WordPress installations. The document body is unreadable, but the heuristics indicate a malicious intent to redirect users through a network of links.

Machine Learning

  • Nyx PDF Classifier malicious score 0.9981

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://dunaweb.co/bg_image/files/7009199287.pdf In PDF document text
    • https://118highschool.am/wp-content/plugins/super-forms/uploads/php/files/3c08fd52e0c73100df2a639b3cfa605c/79402375435.pdfIn PDF document text
    • http://ifap.it/images/file/58567837632.pdfIn PDF document text
    • https://atlasautoglass.com/wp-content/plugins/formcraft/file-upload/server/content/files/16140955c50933---6289840848.pdfIn PDF document text
    • https://zagi.hr/files/77259726076.pdfIn PDF document text
    • http://kyea.org/imageuploads/19359644463.pdfIn PDF document text
    • http://caratow.eu/userfiles/file/81205028562.pdfIn PDF document text
    • http://ck-kutnahora.cz/gais/image/file/pevitusaginubasizub.pdfIn PDF document text
    • https://curewelldiabetes.com/userfiles/file/ludeguwuwilidume.pdfIn PDF document text
    • http://modelkyujin.com/wp-content/plugins/formcraft/file-upload/server/content/files/161317f6364742---58822549893.pdfIn PDF document text
    • http://huyndaicaudien.com/upload/files/57488630558.pdfIn PDF document text
    • https://spacio.hk/attachment/file/wewewazareja.pdfIn PDF document text
    • http://gazetavk.ru/img/file/41886543939.pdfIn PDF document text
    • http://osmed.cz/app/webroot/files/files/40155962247.pdfIn PDF document text
    • http://mtt-association.fr/upload/file/juguvajufizunodaloj.pdfIn PDF document text
    • https://maryamghiasi.com/images/upload/files/kufibazeki.pdfIn PDF document text
    • https://5of7edwardstreet.com/assets/media/files/pusevijilad.pdfIn PDF document text
    • https://alkirbilaw.com/userfiles/files/sejebu.pdfIn PDF document text
    • https://mamap.in/ci/userfiles/files/malexilez.pdfIn PDF document text
    • http://daegyung.kr/userfiles/file/20210908034614.pdfIn PDF document text
    • https://raiporjai.com/piceditor/file/judilodaziza.pdfIn PDF document text
    • http://heathrowairporttaxi.website/userfiles/file/gigukanajibu.pdfIn PDF document text
    • https://feedproxy.google.com/~r/1eyvgo/aqOO/~3/BvfzZFkJO3s/uplcv?utm_term=curtain+system+in+revitPDF 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_off0000d877.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xD877 10416 bytes
SHA-256: 2bc5ad950729a71859804072418dbc51ce3462abd085d8e4e0af18a1a2df7287
font_01_sfnt_off0000f016.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xF016 18940 bytes
SHA-256: a1a5ca57b75b522fe7264ea38f2082de5191d40f0bc376ff3fcccd1d89f2cac5
font_02_sfnt_off000121b1.bin pdf-font-stream PDF embedded font (sfnt) at offset 0x121B1 16792 bytes
SHA-256: 9d2294e344127da9ddc2b77d68b1576b6b78373885bc9da2859f180a98f2c1e1