Malicious PDF — malware analysis report

Static analysis result for SHA-256 c5c96b75731c783d…

MALICIOUS

PDF

61.2 KB Created: 2021-02-12 02:48:59 +02:00 Authoring application: wkhtmltopdf 0.12.5 (via Qt 4.8.7) First seen: 2021-05-26
MD5: 174ccff7f5844ddaa1ca0ed50edfedec SHA-1: 0e042238bf115147b3b47bbd316c1a50b81eb258 SHA-256: c5c96b75731c783d73b035bf12c23cf322a1edd59aca50eab8a17798e44cc1bb
186 Risk Score

Malware Insights

MITRE ATT&CK
T1566.001 Spearphishing Attachment T1203 Exploitation for Client Execution

The PDF contains a large number of external links, identified by the PDF_SEO_LINK_FARM heuristic, pointing to various PDF files on disposable hosting. The ML classifier and ClamAV detection strongly indicate malicious intent, likely related to phishing or malware distribution through these linked documents. The document body is heavily obfuscated and contains metadata suggesting it was generated by wkhtmltopdf, not a typical user document.

Machine Learning

  • Nyx PDF Classifier malicious score 0.9996

Heuristics 6

  • 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 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.
  • 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://baarspo.ru/wb?keyword=10%20freeway%20traffic%20report%20san%20bernardino PDF link annotation
    • https://rovoduwomu.weebly.com/uploads/1/3/5/3/135332400/4203913.pdfIn PDF document text
    • https://mafaredoli.weebly.com/uploads/1/3/2/6/132695491/71ba214141bff.pdfIn PDF document text
    • https://tulivugid.weebly.com/uploads/1/3/4/6/134607321/7396ab307ed2.pdfIn PDF document text
    • https://cdn-cms.f-static.net/uploads/4485156/normal_5fd2de838f3dc.pdfIn PDF document text
    • https://cdn-cms.f-static.net/uploads/4461202/normal_5fd2611be26e3.pdfIn PDF document text
    • https://cdn-cms.f-static.net/uploads/4486356/normal_600f9e87392f1.pdfIn PDF document text
    • https://kerixagagunusuz.weebly.com/uploads/1/3/0/7/130776265/b1dad4279b4.pdfIn PDF document text
    • https://cdn-cms.f-static.net/uploads/4494648/normal_5fd80d9726997.pdfIn PDF document text
    • https://cdn-cms.f-static.net/uploads/4475588/normal_601720e3b78d9.pdfIn PDF document text
    • https://vasinurevesodux.weebly.com/uploads/1/3/4/6/134605286/c46db3007856.pdfIn PDF document text
    • https://static.s123-cdn-static.com/uploads/4505102/normal_5fe417b88c6c0.pdfIn PDF document text
    • https://cdn-cms.f-static.net/uploads/4492246/normal_5fd5f0c68ab8c.pdfIn PDF document text
    • http://www.ascendercorp.com/In PDF document text
    • http://www.ascendercorp.com/typedesigners.htmlIn PDF document text
    • https://s3.amazonaws.com/kosipefojaw/ar_11-_33.pdfIn PDF document text
    • https://s3.amazonaws.com/jupevuxirapi/chislehurst_and_sidcup_grammar_school_uniform_shop.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://scripts.sil.org/OFLIn PDF document text

Extracted artifacts 2

Files carved from inside the sample during analysis.

FilenameKindSourceSize
font_00_sfnt_off0000b0e3.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xB0E3 5548 bytes
SHA-256: 729c2f1d7655fcf9e2c9841ecf80dfb0e4abc4b72967c75e81bca19d64e2e2aa
font_01_sfnt_off0000c3eb.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xC3EB 10416 bytes
SHA-256: f4b0ce621fb947809b7e94cda41396497db458e2fc65d5e36487b04a1f00a887

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