Malicious PDF — malware analysis report

Static analysis result for SHA-256 ec3da8b957b9cd07…

MALICIOUS

PDF

73.3 KB Created: 2021-09-17 18:16:08 +03:00 Authoring application: wkhtmltopdf 0.12.5 (via Qt 5.11.3) First seen: 2021-10-12
MD5: 6bf1e40001813b6f06ac5895cf4ffde1 SHA-1: a9b1760bbaf61df557a2be15e63351151838207f SHA-256: ec3da8b957b9cd078350355c7a168184b22f4d2b110d8f049db0bd61533747bc
156 Risk Score

Malware Insights

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

The PDF contains numerous external links, many pointing to compromised CMS upload storage or disposable hosting, indicating a link farm designed to distribute malicious content. ClamAV and ML classifiers strongly indicate maliciousness, with the primary technique being the use of malicious links to lure users to external sites. The document body is heavily obfuscated and appears to be generated by wkhtmltopdf, providing no direct user-facing lure.

Machine Learning

  • Nyx PDF Classifier malicious score 0.9990

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=bubble+bash+3+android PDF link annotation
    • https://pikhospital.com/ck_uploads/uploads/files/28004609027.pdfIn PDF document text
    • http://precisionsurgicalworks.com/alpha/ckfinder/userfiles/files/bupokalidizipi.pdfIn PDF document text
    • http://devison-matras.com/upload/file/lujegogepaviwozitabokokik.pdfIn PDF document text
    • http://faurau.com/luodan/images/userfiles/file/xuxenofamovokanozeze.pdfIn PDF document text
    • http://eko-gospodarstwo.eu/files/file/daraxagagofakepegud.pdfIn PDF document text
    • http://ipea.kr/userData/board/file/zelepadapaxokulerufegipu.pdfIn PDF document text
    • http://usarsenal.it/userfiles/files/wusubusajuzevavugowujo.pdfIn PDF document text
    • http://paddockj.com/user_data/editor/ckfinder/core/connector/php/upload/files/pagevarizazafa.pdfIn PDF document text
    • http://talesma.com/E/file/99737368611.pdfIn PDF document text
    • https://gencerenerji.com/resimler/files/nokufipigulaluvisojo.pdfIn PDF document text
    • http://npxbyy.com/wang3_3_10_27/Upload/Upload/file/20219111746312654.pdfIn PDF document text
    • https://seger.cz/userfiles/file/12341232544.pdfIn PDF document text
    • http://vinhthuan.com/upload/files/3183861139.pdfIn PDF document text
    • https://www.vibrationmonitoring.asia/wp-content/plugins/formcraft/file-upload/server/content/files/1614097732f865---22746963232.pdfIn PDF document text
    • http://multiseal.com.ph/wp-content/plugins/formcraft/file-upload/server/content/files/161300450764a8---kojalosufobum.pdfIn PDF document text
    • http://hyunshin.net/userfiles/file/86416623514.pdfIn PDF document text
    • http://leylasuren.com/images/userfiles/imagefile/84785266462.pdfIn PDF document text
    • http://stopasbestos.ca/wp-content/plugins/formcraft/file-upload/server/content/files/1613767d6c73c3---nexubofegokidibuwodowal.pdfIn PDF document text
    • http://rabotatver.ru/userfiles/admin/weraliroje.pdfIn PDF document text
    • http://www.norestim.ro/wp-content/plugins/formcraft/file-upload/server/content/files/161345106138aa---mebanafibasewurefalex.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_off0000ba0f.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xBA0F 16792 bytes
SHA-256: 9d2294e344127da9ddc2b77d68b1576b6b78373885bc9da2859f180a98f2c1e1
font_01_sfnt_off0000d221.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xD221 17280 bytes
SHA-256: 1f7ae145dc0c323724248d1891676e97875c5b9bbb89cdce65241dce52be32d2
font_02_sfnt_off0000ff4a.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xFF4A 10712 bytes
SHA-256: 6e72b346995cf3a1ce369ee60a86a45cc5c9d0b7f0c344311e50eb2980b48b25