Malicious PDF — malware analysis report

Static analysis result for SHA-256 1128524958823b5a…

MALICIOUS

PDF

69.7 KB Created: 2021-04-12 17:01:32 +03:00 Authoring application: wkhtmltopdf 0.12.5 (via Qt 4.8.7) First seen: 2021-05-29
MD5: ecf5436d9ce9a1a91961c4f9a1d23e9b SHA-1: 72c74a8335350231978c54e47c91dca81bc9e742 SHA-256: 1128524958823b5a03b4ae7743ed3385684e2b1b5150b5bebe59b1b21f3bd5e5
126 Risk Score

Malware Insights

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

The PDF file was flagged as malicious by ML classifiers and ClamAV, indicating a high likelihood of malicious content. The presence of numerous embedded URLs, many pointing to disposable domains or link farms, suggests a phishing or spamming campaign. The document body, though heavily obfuscated, contains references to 'adverbs worksheets pdf grade 2' and 'wkhtmltopdf', which could be part of a lure to disguise the malicious nature of the PDF.

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 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://www.ofalloncasting.com/sites/default/files/webform/mibotemesasis.pdf In PDF document text
    • https://ambrose.edu/sites/default/files/webform/71048230710.pdfIn PDF document text
    • http://cicatsalud.com/html/sites/default/files/webform/25507329945.pdfIn PDF document text
    • https://web.liderpapel.com/sites/default/files/webform/53484808665.pdfIn PDF document text
    • https://www.mainephilanthropy.org/sites/default/files/5296457674.pdfIn PDF document text
    • https://www.blplegal.com/sites/default/files/webform/piselusani.pdfIn PDF document text
    • https://www.natsihwa.org.au/sites/default/files/webform/setafemamuf.pdfIn PDF document text
    • http://oaklandchildcare.org/sites/default/files/webform/34869944823.pdfIn PDF document text
    • http://cicatsalud.com/html/sites/default/files/webform/65000750087.pdfIn PDF document text
    • https://www.jwico.com/sites/default/files/webform/koxajupenukolipidawikopi.pdfIn PDF document text
    • https://www.osgeurope.com/sites/osg-corporate.dev/files/webform/tajiwugebewozebukak.pdfIn PDF document text
    • https://vectorcorp.net/sites/default/files/webform/resume/dofivefodazewinewes.pdfIn PDF document text
    • https://ambrose.edu/sites/default/files/webform/11364316539.pdfIn PDF document text
    • http://russian-ice-spb.ru/sites/default/files/webform/files/zatepatepekaberemosigedix.pdfIn PDF document text
    • https://www.natsihwa.org.au/sites/default/files/webform/72917344941.pdfIn PDF document text
    • https://www.osgeurope.com/sites/osg-corporate.dev/files/webform/99469138220.pdfIn PDF document text
    • http://www.ascendercorp.com/In PDF document text
    • http://www.ascendercorp.com/typedesigners.htmlIn PDF document text
    • https://feedproxy.google.com/~r/skout/mBVl/~3/A3Ryygt5BCM/uplcv?utm_term=adverbs+worksheets+pdf+grade+2PDF link annotation
    • https://lib.asu.edu/system/files/webform/98562832035.pdfIn PDF document text
    • https://ec.europa.eu/eip/agriculture/sites/default/files/webform/27560642257.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_off0000d385.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xD385 5748 bytes
SHA-256: 7b28b7699429fe438359adc61bd7bb9834b94eea6629a8509728977c796f2751
font_01_sfnt_off0000e72a.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xE72A 10212 bytes
SHA-256: 8964a4432b1c3996acafd074d924f3b47a19791f318bbbb0a79ffb694d9af1da

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