Malicious PDF — malware analysis report

Static analysis result for SHA-256 913dbcdce529e6f1…

MALICIOUS

PDF

68.2 KB Created: 2021-02-26 09:46:02 +02:00 Authoring application: wkhtmltopdf 0.12.5 (via Qt 4.8.7) First seen: 2021-11-07
MD5: 42ca86278f552b922481c55cd75568bd SHA-1: d6056a0a1ca30f590644a7815d5dac872e514cdc SHA-256: 913dbcdce529e6f1816ba135c350b82e85d7eb2819ab4d720debbdce86744e44
156 Risk Score

Malware Insights

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

The PDF file, disguised as a Zyxel modem manual, contains a large number of external links, indicating a link farm or phishing attempt. The ClamAV detection and ML classifier strongly suggest malicious intent, likely to redirect users to malicious sites for further exploitation or credential harvesting. No scripts were extracted, but the PDF structure itself is used to host numerous URLs.

Machine Learning

  • Nyx PDF Classifier malicious score 0.9998

Heuristics 5

  • 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 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.
  • 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/strik?utm_term=zyxel+c1100z+modem+manual PDF link annotation
    • http://avit0.cc/keto_dietsq9yi2.pdfIn PDF document text
    • https://static.s123-cdn-static.com/uploads/4502906/normal_6000906f9eb02.pdfIn PDF document text
    • https://static.s123-cdn-static.com/uploads/4452374/normal_5ffe544a8be1b.pdfIn PDF document text
    • http://keysecret.ru/what_to_do_with_an_explosive_childe9srl.pdfIn PDF document text
    • https://static.s123-cdn-static.com/uploads/4371014/normal_5fdcc8d081836.pdfIn PDF document text
    • https://winugemu.weebly.com/uploads/1/3/1/0/131070294/a082063be.pdfIn PDF document text
    • https://cdn-cms.f-static.net/uploads/4446942/normal_600e6d6562a72.pdfIn PDF document text
    • http://9gusevshop.website/burepemojomiamddo.pdfIn PDF document text
    • https://cdn-cms.f-static.net/uploads/4485004/normal_5fdb88ff81ce4.pdfIn PDF document text
    • https://static.s123-cdn-static.com/uploads/4369330/normal_5fe0a6f3d38ce.pdfIn PDF document text
    • https://xafosaxit.weebly.com/uploads/1/3/1/8/131859261/5f563decbc.pdfIn PDF document text
    • https://cdn-cms.f-static.net/uploads/4502511/normal_602eac1ed9179.pdfIn PDF document text
    • https://static.s123-cdn-static.com/uploads/4409103/normal_600126ed835b4.pdfIn PDF document text
    • http://look-hotel.com/larodegunebvxiru.pdfIn PDF document text
    • http://devlp.design/my_server_is_not_responding3f0n9.pdfIn PDF document text
    • http://kosamaritaj.getenjoyment.net/21533020908.pdfIn PDF document text
    • http://thecaffeinatedstudent.com/muruwoneue8q3.pdfIn PDF document text
    • https://dolevepi.weebly.com/uploads/1/3/4/5/134587457/2699240.pdfIn PDF document text
    • https://static.s123-cdn-static.com/uploads/4367302/normal_5ff715c4cf5d9.pdfIn PDF document text
    • http://www.ascendercorp.com/In PDF document text
    • http://www.ascendercorp.com/typedesigners.htmlIn 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_off0000cfde.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xCFDE 5184 bytes
SHA-256: 03020d383b3515c5bb1ae05a4157487984ecb88dc465929df8e6ce64e51098f4
font_01_sfnt_off0000e18c.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xE18C 9972 bytes
SHA-256: ac5f07cf2094068c92886d41d423b7412a495a3f55207325292e45be2bc9ac9a

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