Malicious PDF — malware analysis report

Static analysis result for SHA-256 786a17f20820e62f…

MALICIOUS

PDF

72.2 KB Created: 2021-04-07 17:23:47 +03:00 Authoring application: wkhtmltopdf 0.12.5 (via Qt 4.8.7) First seen: 2021-05-26
MD5: 2a9ee0912e042a364cd8dabf7a69974f SHA-1: 16b373ff56557b1591786ccc86aa54b44806871b SHA-256: 786a17f20820e62f48e5ed9f7c85e7423b32e7472ed40defe959edafe22b968b
126 Risk Score

Malware Insights

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

The PDF file was flagged by ML classifiers and ClamAV as malicious, specifically as a phishing trojan. It contains numerous embedded URLs, many pointing to link farms disguised as educational resources, such as 'nios d. el. ed solved assignment pdf in hindi'. The heuristic 'PDF_SEO_DISPOSABLE_LINK_FARM' indicates a pattern of using disposable hosting for link aggregation, a common tactic for phishing or malware distribution. No scripts were extracted, but the presence of multiple external URIs suggests an attempt to redirect the user to malicious content.

Machine Learning

  • Nyx PDF Classifier malicious score 0.9997

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 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://ambrose.edu/sites/default/files/webform/nakevatekiviva.pdf In PDF document text
    • https://www.mothercare.ro/sites/default/files/webform/resumes/42535902170.pdfIn PDF document text
    • https://ambrose.edu/sites/default/files/webform/74647609277.pdfIn PDF document text
    • http://klm3fg.grhosting.cz/sites/default/files/webform/files/tekuxegejarikuferibo.pdfIn PDF document text
    • http://russian-ice-spb.ru/sites/default/files/webform/files/77599308563.pdfIn PDF document text
    • http://www.friendlycc.com/sites/default/files/webform/74296331991.pdfIn PDF document text
    • https://www.mothercare.ro/sites/default/files/webform/resumes/tizagoge.pdfIn PDF document text
    • https://www.natsihwa.org.au/sites/default/files/webform/lavajaruzapelusudixavu.pdfIn PDF document text
    • http://russian-ice-spb.ru/sites/default/files/webform/files/69309865186.pdfIn PDF document text
    • https://www.uts.cw/sites/default/files/webform/tizodakemepegipupimegoxi.pdfIn PDF document text
    • http://www.ascendercorp.com/In PDF document text
    • http://www.ascendercorp.com/typedesigners.htmlIn PDF document text
    • http://feedproxy.google.com/~r/Uplcv/~3/Om9ozkHLxGw/uplcv?utm_term=nios+d.+el.+ed+solved+assignment+pdf+in+hindiPDF link annotation
    • https://www.ice.cam.ac.uk/sites/www.ice.cam.ac.uk/files/webform/10713621665.pdfIn PDF document text
    • https://www.ice.cam.ac.uk/sites/www.ice.cam.ac.uk/files/webform/ruwitik.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
    • http://dejavu.sourceforge.netIn PDF document text
    • http://dejavu.sourceforge.net/wiki/index.php/LicenseIn PDF document text

Extracted artifacts 3

Files carved from inside the sample during analysis.

FilenameKindSourceSize
font_00_sfnt_off0000c50b.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xC50B 5420 bytes
SHA-256: a90bcb75a4dc0608105c7846271e926a57b7c8d9f7ea39fa43d2ed3b3b4e1049
font_01_sfnt_off0000d770.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xD770 10712 bytes
SHA-256: 9847b430eedbd285ef2f93d06e2fe6f09bd2d7afb20d492f8cab9f13a04f1057
font_02_sfnt_off0000fc55.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xFC55 16204 bytes
SHA-256: 31aa257675234f953cb39254c73a0c002637764ec2691c470e0912636c3685cf

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