Malicious PDF — malware analysis report

Static analysis result for SHA-256 1f581d05559be28a…

MALICIOUS

PDF

89.3 KB Created: 2021-06-12 19:56:23 +03:00 Authoring application: wkhtmltopdf 0.12.5 (via Qt 4.8.7)
MD5: 4dfb2d0b3b688409830f09e31c705aad SHA-1: dfc3a048deaee90d922a2d19a72fc624e43012f4 SHA-256: 1f581d05559be28a5577a007f5c1f717140ece260c92fdd30551ba200685d3e1
186 Risk Score

Malware Insights

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

This PDF sample was flagged by multiple heuristics and a machine learning classifier as malicious, specifically as a phishing trojan. It contains a large number of external links pointing to PDFs hosted on various disposable domains, suggesting a link farm or SEO manipulation tactic. The presence of numerous external links and the high ML score indicate a strong likelihood of malicious intent, potentially to distribute further malware or lead users to phishing 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://krisoc.ru/pbw?utm_term=descriptive+research+design
    • https://jegivobepumo.weebly.com/uploads/1/3/4/4/134444156/daxinonot.pdf
    • https://xurigaguk.weebly.com/uploads/1/3/4/6/134635426/sujiker-valulit-gogebevad.pdf
    • https://cdn-cms.f-static.net/uploads/4414691/normal_60347b827be83.pdf
    • https://static.s123-cdn-static.com/uploads/4371023/normal_6006b3d3b1a12.pdf
    • https://nometoxuf.weebly.com/uploads/1/3/4/2/134266561/5500aea9037e5e9.pdf
    • https://jufesuzukexo.weebly.com/uploads/1/3/5/2/135294717/defug.pdf
    • https://tidixusega.weebly.com/uploads/1/3/1/3/131380021/4584649.pdf
    • https://juludonidodag.weebly.com/uploads/1/3/4/7/134706402/2636970.pdf
    • https://zodutobaziji.weebly.com/uploads/1/3/1/4/131408241/4360736.pdf
    • https://nipizizit.weebly.com/uploads/1/3/0/9/130969905/xopox_luvitis_vemig_lolofev.pdf
    • https://valezofijamope.weebly.com/uploads/1/3/4/4/134445284/9058204.pdf
    • https://sidomepavoresob.weebly.com/uploads/1/3/5/3/135322675/bcde4.pdf
    • https://dikurowewo.weebly.com/uploads/1/3/4/8/134893632/rokopefosaw.pdf
    • https://static.s123-cdn-static.com/uploads/4365649/normal_5fe60088efdf0.pdf
    • https://bemetapijulew.weebly.com/uploads/1/3/1/4/131437656/5709682.pdf
    • http://www.ascendercorp.com/
    • http://www.ascendercorp.com/typedesigners.html
    • https://uploads.strikinglycdn.com/files/39e20f83-85dc-4495-a2d3-9911e939aff8/mojidenifuzimokomijejota.pdf
    • https://uploads.strikinglycdn.com/files/adc9e14a-36ef-4029-b0a2-07cf5aaeb55e/lord_of_the_rings_characters_names_and_pictures.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_off00011ff7.bin
f131526d517bbd2cbeca25f6fb4c0ab3da921591aba52fa14b2e2929da1e6b0b		 pdf-font-stream PDF embedded font (sfnt) at offset 0x11FF7 5360 bytes
font_01_sfnt_off0001323d.bin
d1a789ce8981778fe0bc5198c37639967afc865380489578dd0cf5056710d318		 pdf-font-stream PDF embedded font (sfnt) at offset 0x1323D 10660 bytes

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