Malicious PDF — malware analysis report

Static analysis result for SHA-256 51cd6385712bf9a7…

MALICIOUS

PDF

95.5 KB Created: 2021-09-06 21:12:23 +03:00 Authoring application: wkhtmltopdf 0.12.5 (via Qt 5.11.3) First seen: 2021-10-16
MD5: ff0213054a9c053a541508f1c4f5d2e4 SHA-1: 44582b517fc730bce8c76f9ce81a0a40351d82a6 SHA-256: 51cd6385712bf9a74f29d3af05cba68eba70cfb361017b7c63db2019b8e1c2ab
176 Risk Score

Malware Insights

MITRE ATT&CK
T1566.001 Spearphishing Attachment

The PDF contains a large number of embedded links, many pointing to potentially compromised websites, disguised as a dictionary resource. The ML classifier and ClamAV detection strongly indicate malicious intent, likely to redirect users to phishing or malware download sites. Although no scripts were explicitly extracted, the malformed stream length and link farm heuristics suggest an attempt to exploit PDF vulnerabilities or deliver malicious content.

Machine Learning

  • Nyx PDF Classifier malicious score 0.9968

Heuristics 7

  • ClamAV: Pdf.Phishing.Trojan-d2568dad23a94d95-d2568dad23a94d95-10044375-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Pdf.Phishing.Trojan-d2568dad23a94d95-d2568dad23a94d95-10044375-0
  • Malformed active-content stream length medium PDF_MALFORMED_EXPLOIT_STREAM_LENGTH
    A PDF stream that carries active/exploit-looking content has a declared /Length that does not match the recovered stream body. Malformed stream boundaries and length mismatches are common parser-evasion/supporting evidence around Reader exploit streams.
  • 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://anukulagrotech.com/ci/userfiles/files/87026693856.pdf In PDF document text
    • https://swagath.co/new/ckfinder/userfiles/files/51588366143.pdfIn PDF document text
    • http://zadonskiy.ru/wp-content/plugins/formcraft/file-upload/server/content/files/160e536a80cc7e---timidaletukijuzi.pdfIn PDF document text
    • http://www.sunarpazarlama.com/wp-content/plugins/super-forms/uploads/php/files/8epo2gc66me4lta0hh03kaub45/xamibagud.pdfIn PDF document text
    • https://intelean.com/wp-content/plugins/formcraft/file-upload/server/content/files/16103b19462457---19197412817.pdfIn PDF document text
    • https://fastcomputer.vn/wp-content/plugins/super-forms/uploads/php/files/210193d320273d938771ed04f90bb4e6/bosekunomozitoz.pdfIn PDF document text
    • https://yodishit.com/uploads/userfiles/file/89374161609.pdfIn PDF document text
    • http://savaksangida.com/resimler/files/lefigonifujipi.pdfIn PDF document text
    • https://widepolymers.com/userfiles/file/44566261747.pdfIn PDF document text
    • http://intechsol.kz/wp-content/plugins/formcraft/file-upload/server/content/files/160c29d6be8ae6---72947934974.pdfIn PDF document text
    • http://giaexploring.it/userfiles/files/8155848157.pdfIn PDF document text
    • http://m2m2design.com/userfiles/89949812360.pdfIn PDF document text
    • https://ivanamihic.com//files/9619592912.pdfIn PDF document text
    • https://stefandes.com/wp-content/plugins/formcraft/file-upload/server/content/files/160b441e715d77---rotefitabi.pdfIn PDF document text
    • http://teplospectr.ru/images/files/11976069692.pdfIn PDF document text
    • http://homeopathyhongkong.com/files/38273148542.pdfIn PDF document text
    • http://baharemadinah.com/wp-content/plugins/formcraft/file-upload/server/content/files/1606e2bdedcd3b---woreligivoxuwiz.pdfIn PDF document text
    • http://jamoncup.es/wp-content/plugins/formcraft/file-upload/server/content/files/160a27e4d25e4f---93898855609.pdfIn PDF document text
    • http://jinshi66.com/uploadfiles/files/bajabupuzoduvaferug.pdfIn PDF document text
    • https://tselectromechanical.com/uploads/CKfiles/files/sulovupopobasedaza.pdfIn PDF document text
    • http://utpcomp.ru/uploads/files/vowofolozesosudebin.pdfIn PDF document text
    • https://teenvolunteerhouston.org/wp-content/plugins/super-forms/uploads/php/files/6e33ac1be2575539d1f6730b2b77e980/69004579466.pdfIn PDF document text
    • https://www.booster-p.com/wp-content/plugins/formcraft/file-upload/server/content/files/1610e246161a2d---29152462580.pdfIn PDF document text
    • https://autosofortkauf.ch/wp-content/plugins/super-forms/uploads/php/files/q72eif63tv7fge02f8vi3us3ee/kusafaganibanisop.pdfIn PDF document text
    • https://clinicscrm.com/img/files/91575209990.pdfIn PDF document text
    • https://feedproxy.google.com/~r/Uplcv/~3/DOqCt-cVA4I/uplcv?utm_term=japanese+english+bilingual+visual+dictionary+%28dk+visual+dictionaries%29+pdfPDF 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_off000100fb.bin pdf-font-stream PDF embedded font (sfnt) at offset 0x100FB 11556 bytes
SHA-256: 9feaf9a3253b84ae4733ecfd75df3a3576e47e0c5a3148f2abdffe34d9306578
font_01_sfnt_off00011c10.bin pdf-font-stream PDF embedded font (sfnt) at offset 0x11C10 23256 bytes
SHA-256: 880b3aad23dfbd84ab3be79d82baf2c4039328465aa1276f7549bb31521d7e00
font_02_sfnt_off00015732.bin pdf-font-stream PDF embedded font (sfnt) at offset 0x15732 16792 bytes
SHA-256: 9d2294e344127da9ddc2b77d68b1576b6b78373885bc9da2859f180a98f2c1e1

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