Malicious PDF — malware analysis report

Static analysis result for SHA-256 51cda715ce107a93…

MALICIOUS

PDF

72.5 KB Created: 2021-04-30 12:02:58 +03:00 Authoring application: wkhtmltopdf 0.12.5 (via Qt 4.8.7)
MD5: 8c104137efec41aec7e47a185d3ad0b9 SHA-1: 199c2471d36d6cd355f0bf9cb58ca73c6d1bc1d3 SHA-256: 51cda715ce107a93708ce9106c3eb3c0fdc84ec60e704cf378772fec4fa9ddde
186 Risk Score

Malware Insights

MITRE ATT&CK
T1566.001 Spearphishing Attachment T1059.007 JavaScript

The PDF file contains numerous external links, many hosted on disposable domains, indicating a link farm or phishing operation. The ML classifier and ClamAV detection strongly suggest malicious intent. While no scripts were explicitly extracted, the PDF structure and embedded URLs point towards a phishing or malware distribution campaign, likely initiated via spearphishing.

Machine Learning

  • Nyx PDF Classifier malicious score 0.9996

Heuristics 6

  • Small PDF contains mass external PDF link farm critical PDF_SEO_LINK_FARM
    Small PDF contains many clickable external PDF links, mostly clustered on one host. This matches generated SEO/link-farm PDF carriers used to route users into malicious or unwanted-software delivery chains, rather than a normal document citation pattern.
  • ClamAV: Pdf.Phishing.Trojan-d2528dad23a95d95-d2528dad23a95d95-10044376-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Pdf.Phishing.Trojan-d2528dad23a95d95-d2528dad23a95d95-10044376-0
  • 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://bologen.ru/strik?utm_term=sat+test+scores
    • https://guzesunidami.weebly.com/uploads/1/3/0/8/130873942/1319465334.pdf
    • http://albatros-trans.ru/10_snf_kimya_esen_yaynlar_indir6tzoa.pdf
    • https://xesisawizes.weebly.com/uploads/1/3/1/6/131606125/gibitorevagijo.pdf
    • http://about-central.com/75313527200lulb7.pdf
    • https://nikavazoz.weebly.com/uploads/1/3/1/4/131452929/c12a6117ef.pdf
    • https://cdn-cms.f-static.net/uploads/4492900/normal_6023f97c40602.pdf
    • https://zumegopepotiko.weebly.com/uploads/1/3/1/3/131398003/gugusefip-romepusalukut-wesogus.pdf
    • https://pibefugaradaxo.weebly.com/uploads/1/3/1/3/131398186/tizuzixepi_galomi.pdf
    • https://pulosonimoge.weebly.com/uploads/1/3/0/7/130739093/parax_febegeki.pdf
    • http://politach.com/where_is_the_serial_number_on_my_baldwin_acrosonic_pianosw5fh.pdf
    • https://felinabaf.weebly.com/uploads/1/3/4/3/134380667/buvasiwusafoluwax.pdf
    • https://nasuxixogidipan.weebly.com/uploads/1/3/4/7/134701521/f0a89092.pdf
    • https://cdn-cms.f-static.net/uploads/4383801/normal_603bdd6fe84e4.pdf
    • http://perfectiona.online/how_many_supermarket_staff_have_died_from_covid_19y3ie0.pdf
    • https://dajixogemozuv.weebly.com/uploads/1/3/1/4/131438707/a80008ea3baa.pdf
    • http://www.ascendercorp.com/
    • http://www.ascendercorp.com/typedesigners.html
    • http://kowetomad.epizy.com/vudenujomuvelexo.pdf
    • http://sidegiri.epizy.com/61409977728.pdf
    • http://falisetiven.epizy.com/56102687512.pdf
    • https://s3.amazonaws.com/jukoxisojow/23608706001.pdf
    • https://s3.amazonaws.com/tadevewuju/jonathan_gold_101_los_angeles_book.pdf
    • https://s3.amazonaws.com/vizegemawokaxe/22697390993.pdf
    • http://www.w3.org/1999/02/22-rdf-syntax-ns#
    • http://purl.org/dc/elements/1.1/
    • http://ns.adobe.com/pdf/1.3/
    • http://ns.adobe.com/xap/1.0/
    • http://ns.adobe.com/xap/1.0/mm/
    • http://ns.adobe.com/xap/1.0/rights/
    • http://scripts.sil.org/OFL

Extracted artifacts 2

Files carved from inside the sample during analysis.

FilenameKindSourceSize
font_00_sfnt_off0000e08d.bin
28e0e2e4168228c5067e5f1fab497af0f2a7769119b2842c3bf9c34483ae12d5		 pdf-font-stream PDF embedded font (sfnt) at offset 0xE08D 4864 bytes
font_01_sfnt_off0000f120.bin
99c64dee7f1482319bde82310c561e29ce6e02678fafab6a821a82ea30a501a9		 pdf-font-stream PDF embedded font (sfnt) at offset 0xF120 10400 bytes

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