Malicious PDF — malware analysis report

Static analysis result for SHA-256 66027ab1fc41a9e2…

MALICIOUS

PDF

74.1 KB Created: 2021-04-06 21:50:32 +03:00 Authoring application: wkhtmltopdf 0.12.5 (via Qt 4.8.7) First seen: 2021-05-29
MD5: eaf798f0f3a2f2568f7f4db09892b323 SHA-1: 30fbed0e45b2846a8509ca33afce91838a63afd7 SHA-256: 66027ab1fc41a9e2c676407a6b05cd4bc2e4d339f3bda94d8e769b971b7e0f54
126 Risk Score

Malware Insights

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

The PDF was flagged by a machine learning classifier and ClamAV as malicious, specifically as a phishing trojan. Heuristics indicate it functions as a link farm, with numerous embedded URLs pointing to potentially malicious or disposable domains. The document body, though heavily obfuscated, contains metadata suggesting it was generated by wkhtmltopdf, a tool sometimes used to create malicious PDFs.

Machine Learning

  • Nyx PDF Classifier malicious score 0.9998

Heuristics 5

  • ClamAV: Pdf.Phishing.Trojan-d2528dad23a95d95-d2528dad23a95d95-10044376-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Pdf.Phishing.Trojan-d2528dad23a95d95-d2528dad23a95d95-10044376-0
  • 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://architecturaldesigninc.com/sites/default/files/36110977311.pdf In PDF document text
    • http://cicatsalud.com/html/sites/default/files/webform/mulakipezumaxusilexuvu.pdfIn PDF document text
    • https://www.enwidth.com/sites/default/files/webform/resumes/sojinikud.pdfIn PDF document text
    • https://ambrose.edu/sites/default/files/webform/bunovodedodasu.pdfIn PDF document text
    • https://architecturaldesigninc.com/sites/default/files/sujuxot.pdfIn PDF document text
    • http://cicatsalud.com/html/sites/default/files/webform/32041770382.pdfIn PDF document text
    • https://www.mainephilanthropy.org/sites/default/files/wimatetomowitiki.pdfIn PDF document text
    • http://www.pacificsportfraservalley.com/sites/default/files/webform/newusagolepilukakatukus.pdfIn PDF document text
    • http://spotlight-sites.com/sites/default/files/webform/sizewavajifur.pdfIn PDF document text
    • http://www.friendlycc.com/sites/default/files/webform/74296331991.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/~3/6naE_Nh8_CY/uplcv?utm_term=athletic+body+in+balance+gray+cook+pdfPDF link annotation
    • https://thesanfordschool.asu.edu/sites/default/files/webform/85266863194.pdfIn PDF document text
    • https://www.vub.be/sites/vub/files/webform/fazarixi.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_off0000e648.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xE648 5536 bytes
SHA-256: 97871f130bd3029269a4aa56346b6a04c9b3d09a8864db5d0327a51200bd6aa5
font_01_sfnt_off0000f921.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xF921 10352 bytes
SHA-256: ef75d26ea5cb7aff2e7900ea3b14c3836aa2a2bc2b4a2fcc4306b49abbe882da

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