Malicious PDF — malware analysis report

Static analysis result for SHA-256 e70cc1cb3d67e428…

MALICIOUS

PDF

75.0 KB Created: 2021-04-10 20:35:10 +03:00 Authoring application: wkhtmltopdf 0.12.5 (via Qt 4.8.7)
MD5: 0146c8d695916c8fb32cf2f2952e981c SHA-1: e8827e09513c7da966bd86ceaf726f408c43b8e4 SHA-256: e70cc1cb3d67e428c7d0d4a000de9497c87b716ef8917865561ff7ab6047c947
156 Risk Score

Malware Insights

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

This PDF file was detected as malicious by ClamAV and an ML classifier, indicating a high likelihood of malicious intent. It contains a large number of external links, characteristic of a link farm, with the primary URL being https://jacksth.ru/strik. The document body, though partially corrupted, suggests a lure related to educational material ('Nouns number worksheet for class 5') to encourage clicks on these links. No scripts were extracted, but the PDF structure itself facilitates the link farm attack pattern.

Machine Learning

  • Nyx PDF Classifier malicious score 0.9997

Heuristics 5

  • 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
  • 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=nouns+number+worksheet+for+class+5
    • http://nobadunitedowa.22web.org/how_to_use_graco_x7_airless_paint_sprayer.pdf
    • https://cdn-cms.f-static.net/uploads/4452618/normal_6015b6d0b4d6e.pdf
    • https://cdn-cms.f-static.net/uploads/4411683/normal_60311a057f1da.pdf
    • http://vatologox.iblogger.org/nomumusidelugexav.pdf
    • https://cdn-cms.f-static.net/uploads/4407983/normal_605159dbbabab.pdf
    • https://cdn-cms.f-static.net/uploads/4373992/normal_6056f703c892f.pdf
    • http://www.ascendercorp.com/
    • http://www.ascendercorp.com/typedesigners.html
    • https://uploads.strikinglycdn.com/files/55865ca9-f0c9-4694-aed9-cc333c65b1a9/fuparujubemugodabevisim.pdf
    • https://uploads.strikinglycdn.com/files/7439816b-23bb-4fba-953a-c72466a93d51/bilob.pdf
    • https://87da31d5-d184-45e7-a456-0ad082c8bd65.filesusr.com/ugd/55e94a_a750ca93adac44988bdcde87839dbff7.pdf?index=true
    • http://xuvitus.rf.gd/tratamiento_para_anemia_hemolitica.pdf
    • https://uploads.strikinglycdn.com/files/cf37cb77-4bf1-490c-992d-025299f5feed/reddit_pokemon_go_promo_codes_december_2020.pdf
    • https://uploads.strikinglycdn.com/files/f98858e8-12f8-4bbc-8ca1-02fb875c5260/77911921276.pdf
    • https://uploads.strikinglycdn.com/files/f697f913-4711-479a-98b5-60d23d813aee/ryobi_bs900_band_saw_blades.pdf
    • https://5ccda086-29c7-4024-8a93-689df1f3b89c.filesusr.com/ugd/ed8107_24dc9c66142946aa9fdd554453a79139.pdf?index=true
    • https://uploads.strikinglycdn.com/files/ac2ac7a3-c759-4e6f-9e1b-d30882c13d0c/how_to_start_a_literature_review_example.pdf
    • https://ef733714-782c-48ea-8991-1bc0bf0c95f2.filesusr.com/ugd/ad2ade_0c24c51d711b45da93140d627afec527.pdf?index=true
    • https://uploads.strikinglycdn.com/files/1e9390a2-8c80-4d20-bcc0-b71c9f245aa2/who_plays_jean_valjean_in_les_miserables_25th_anniversary.pdf
    • http://lojupodinitaxug.epizy.com/9535874916.pdf
    • https://uploads.strikinglycdn.com/files/c48d0332-371d-4f5f-a6bf-29d300745e7c/dizefexabuvol.pdf
    • http://wubifut.rf.gd/distinguish_between_intranet_and_extranet.pdf
    • https://uploads.strikinglycdn.com/files/d859f97e-1915-4e16-9e72-5d0175d12904/lowrance_elite_5_hdi_extension_cable.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_off0000e69e.bin
0d7aff02d4091ce0b989cdcc26936390624e0f738b03e3f3a06758391be3397c		 pdf-font-stream PDF embedded font (sfnt) at offset 0xE69E 5512 bytes
font_01_sfnt_off0000f953.bin
09348a1354d629cfd0827d26da4e223d760f39cb445b8e421f7158898570e4b2		 pdf-font-stream PDF embedded font (sfnt) at offset 0xF953 10852 bytes

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