Malicious PDF — malware analysis report

Static analysis result for SHA-256 b8f8572a7d6e644e…

MALICIOUS

PDF

79.5 KB Created: 2021-03-25 05:41:53 +02:00 Authoring application: wkhtmltopdf 0.12.5 (via Qt 4.8.7)
MD5: cd23b0b7ff1788388c8d6c62cc87218a SHA-1: 99727cf2267aa2ec5f2b2b0f43b775c9ec89fe16 SHA-256: b8f8572a7d6e644ed4d2fe29c4e6c38f00574d86354b4927ec2d066dd90242d8
156 Risk Score

Malware Insights

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

The PDF contains numerous external links, with one heuristic specifically identifying a 'mass external PDF link farm'. The document body, though heavily obfuscated, suggests a lure related to an 'online spanish textbook'. The presence of multiple unknown and potentially malicious URLs, combined with a high ML score and ClamAV detection, indicates a phishing or malware distribution attempt. No scripts were extracted, but the PDF structure itself facilitates the redirection.

Machine Learning

  • Nyx PDF Classifier malicious score 0.9996

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://druttle.ru/wix?keyword=online+spanish+textbook+avancemos+2
    • http://meetcabinets.xyz/8691875349vfjnu.pdf
    • https://cdn-cms.f-static.net/uploads/4368222/normal_600fb79fecb51.pdf
    • http://realwockyc.info/adventure_game_for_android_mobileu15zp.pdf
    • https://cdn-cms.f-static.net/uploads/4413225/normal_6034c4976c371.pdf
    • http://www.ascendercorp.com/
    • http://www.ascendercorp.com/typedesigners.html
    • http://www.daltonmaag.com/
    • https://s3.amazonaws.com/wupiwupiwot/primary_school_admission_form_sample.pdf
    • https://7ae52be2-ba3c-41fb-8935-29281088223e.filesusr.com/ugd/affaa6_f0276105f1c64a33a8e9e3615b1c8afa.pdf?index=true
    • https://s3.amazonaws.com/punagilelabon/mawivamuradupowotadipe.pdf
    • https://s3.amazonaws.com/moduxanakuri/algebra_1_solving_equations_answers.pdf
    • https://6c403777-3bdb-430d-a4ca-23d5788374d5.filesusr.com/ugd/e0034b_28ec003e59324ef89e6bb7b971552740.pdf?index=true
    • https://b01cffea-7a05-49e8-9781-04202a21c04b.filesusr.com/ugd/d5d855_c93e9f9979774dd4922e6a3ceeaf3d4c.pdf?index=true
    • https://9e2901ea-5d25-41a5-867c-54d0774c6e48.filesusr.com/ugd/4d0f37_06732aa25d3d4088b4ff82578c3e7acb.pdf?index=true
    • https://s3.amazonaws.com/liwafo/100_startup_review.pdf
    • https://s3.amazonaws.com/lixisariwulo/affect_vs._effect_worksheet_answer_key.pdf
    • https://s3.amazonaws.com/xafaxotaful/72881020247.pdf
    • https://s3.amazonaws.com/vovuzize/do_infj_and_infp_get_along.pdf
    • https://s3.amazonaws.com/lemefofutomapox/modern_family_episode_guide.pdf
    • https://s3.amazonaws.com/zalomi/creative_resume_maker_online_free.pdf
    • https://s3.amazonaws.com/sosupejuxofedo/28978120373.pdf
    • https://s3.amazonaws.com/wumodukubaru/football_scouting_report.pdf
    • https://s3.amazonaws.com/nilititonawafim/anopheles_arabiensis.pdf
    • https://s3.amazonaws.com/fewifuwu/52646355282.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 3

Files carved from inside the sample during analysis.

FilenameKindSourceSize
font_00_sfnt_off0000e549.bin
0337d1a55addb00736417d239b75100e227cdb39abcf7af94318ecc7f76f9a20		 pdf-font-stream PDF embedded font (sfnt) at offset 0xE549 5356 bytes
font_01_sfnt_off0000f754.bin
128c117e7f8a207c5ee57fa5b225fe8160e0e307fe3cdc1ad87a37e16064956e		 pdf-font-stream PDF embedded font (sfnt) at offset 0xF754 12600 bytes
font_02_sfnt_off000120f1.bin
0d0f64e27578eb124b8bc81c7eceacdd166e22eddd95c81328e9fbd7de2a6333		 pdf-font-stream PDF embedded font (sfnt) at offset 0x120F1 4324 bytes

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