Malicious PDF — malware analysis report

Static analysis result for SHA-256 61ff4aba99398eff…

MALICIOUS

PDF

81.4 KB Created: 2021-03-14 21:35:09 +02:00 Authoring application: wkhtmltopdf 0.12.5 (via Qt 4.8.7)
MD5: d8e58479531ce1a2f0545b4ceb710b9d SHA-1: 19489e939186d8db2e913ef9f0954ea03b1ca1c5 SHA-256: 61ff4aba99398eff2ef2392670d26adf15a1f0410e33eda0be96d14e5f4c4302
186 Risk Score

Malware Insights

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

The PDF file was flagged as malicious by ClamAV and an ML classifier, indicating a high likelihood of malicious intent. It contains a large number of external links, many pointing to disposable domains, suggesting a link farm or phishing operation. The presence of embedded URLs and the heuristic 'PDF_SEO_LINK_FARM' further support this, indicating the document's primary purpose is to redirect users to potentially harmful external sites.

Machine Learning

  • Nyx PDF Classifier malicious score 0.9998

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-d2568dad23a94d95-d2568dad23a94d95-10044375-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Pdf.Phishing.Trojan-d2568dad23a94d95-d2568dad23a94d95-10044375-0
  • 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://jacksth.ru/strik?utm_term=samsung+galaxy+note+4+lcd+%2526+touch+screen+assembly+replacement
    • http://tesar-krd.ru/sims_3_all_expansion_packs_download_macogkvc.pdf
    • http://d2-club.ru/8251232543729fw0.pdf
    • http://gutufozif.iblogger.org/36471640556.pdf
    • http://myluckybet.xyz/85506853068g8zyj.pdf
    • http://www.ascendercorp.com/
    • http://www.ascendercorp.com/typedesigners.html
    • https://uploads.strikinglycdn.com/files/b2c035ab-bd4d-4784-aff9-df88d1149bce/xepibereme.pdf
    • https://43dda2ad-fadc-418c-a2d5-4b96cca2ed60.filesusr.com/ugd/6eca9c_d4584867760f4314890702f769fee396.pdf?index=true
    • http://bajivuselome.epizy.com/how_to_use_bitmoji_in_google_classroom.pdf
    • https://6632aaff-1fe9-4f1d-acb3-7d444e457837.filesusr.com/ugd/ce4b7c_d873e0edf54e404588bc5a26851c2d74.pdf?index=true
    • http://rubijisezet.epizy.com/vukepomuwekubeni.pdf
    • https://13fad4bf-7224-44b3-802b-16842e97d241.filesusr.com/ugd/b14664_5b7b07b289ef418eb14477c7cb7c3347.pdf?index=true
    • http://zodazuwofapodu.epizy.com/ballet_exercise_music_free.pdf
    • https://e6676b24-921d-4f57-8fca-beda98688f3c.filesusr.com/ugd/144d27_b256b186f79846ca8f83a486afc3d91d.pdf?index=true
    • https://uploads.strikinglycdn.com/files/15389f94-3f1c-4bd5-b63e-67ac01e899bb/zojigudabuvod.pdf
    • https://8271b8e8-1520-4b18-8785-2fafc8cd33e6.filesusr.com/ugd/efc97f_706839a60759445cb6e49d0e17004549.pdf?index=true
    • https://c8019651-2137-4367-b38e-775fff3f8a75.filesusr.com/ugd/fc5a02_f49d73ddd7124eb3bd6ecdfd3ea00c79.pdf?index=true
    • https://uploads.strikinglycdn.com/files/683465b8-5c31-4812-8062-d633be79645c/18300392393.pdf
    • https://6bb2b61b-82bf-473b-8365-63ddb02ddbdd.filesusr.com/ugd/d55797_a8824fd5cb1243d5940879aee895492b.pdf?index=true
    • https://88211235-bf86-4d40-a6ec-a052db2f682e.filesusr.com/ugd/94e5ef_6b37c8d00755467b9eb78674241fe35a.pdf?index=true
    • 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_off0000ff13.bin
71556c57469e95fc3da2d8f59e6d09c5bb451b9d8c356443dbd56d7e691b2c5c		 pdf-font-stream PDF embedded font (sfnt) at offset 0xFF13 5524 bytes
font_01_sfnt_off000111e5.bin
918757e44c2a711593569d3f0c1fb90cb2bb9281ff4c5491cae43967de7a4482		 pdf-font-stream PDF embedded font (sfnt) at offset 0x111E5 10796 bytes

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