Malicious PDF — malware analysis report

Static analysis result for SHA-256 a38cfb52c5e217c4…

MALICIOUS

PDF

79.0 KB Created: 2021-07-15 15:40:45 +03:00 Authoring application: wkhtmltopdf 0.12.5 (via Qt 5.11.3) First seen: 2021-08-25
MD5: 690e7b0914befe0c635da37ee78b42f9 SHA-1: b18df6d0ef8170cfdd4c7072a6a549f2363634c0 SHA-256: a38cfb52c5e217c4fa4175020044c94b26169186afb16f91c6ec84089b3ee9c0
176 Risk Score

Malware Insights

MITRE ATT&CK
T1566.001 Spearphishing Attachment T1553.005 Security Software Installation

The PDF file was flagged by ClamAV as a phishing trojan. Heuristics indicate it uses an image lure linking to a redirector, and importantly, contains instructions to disable security software. While no scripts were extracted, the combination of these factors strongly suggests a phishing or malware delivery attempt.

Machine Learning

  • Nyx PDF Classifier malicious score 0.6166

Heuristics 6

  • ClamAV: Pdf.Phishing.Trojan-d2568dad23a94d95-d2568dad23a94d95-10044375-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Pdf.Phishing.Trojan-d2568dad23a94d95-d2568dad23a94d95-10044375-0
  • Image lure linking to an SEO redirector (free-download phishing) high PDF_SEO_UTM_REDIRECTOR_LINK
    PDF embeds an image with little or no body text and a clickable link to a multi-word utm_term / FeedBurner-proxied SEO redirector — the 'free ebook / solution-manual / document download' phishing family that ranks for natural-language search queries and routes the user into a payload/redirect chain. The PDF carries no exploit; the risk is the linked destination. Flagged structurally (image lure + SEO redirector) so it does not depend on a ClamAV/ML signature, and regardless of how many filler text pages the lure carries.
  • Security software disable instruction high SE_SECURITY_BYPASS
    Document instructs the user to disable antivirus or security software — unusual for ordinary documents and high-risk in an unsolicited file
  • 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://feedproxy.google.com/~r/sq/ugae/~3/iYdez4bKglI/square?utm_term=port+22+connection+refused+windows PDF link annotation
    • https://static1.squarespace.com/static/60bf69b23f3791685666e32d/t/60ee369bfd66ff3739edfc62/1626224283618/measles_vaccine_for_adults.pdfIn PDF document text
    • https://static1.squarespace.com/static/60aac5994c6b1805bc4acbdb/t/60e88dc74374720c364e8172/1625853383268/california_form_540_instructions_2020.pdfIn PDF document text
    • https://static1.squarespace.com/static/60bf6cad3a95e91b59aa2418/t/60edc1caf6d8087912bb80af/1626194378178/what_do_you_understand_by_organisation.pdfIn PDF document text
    • https://static1.squarespace.com/static/60bf6bff0d8d387fecc8b153/t/60e94ea127127e6804173671/1625902754125/finite_element_method_lecture_notes.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://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_off0000d2b0.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xD2B0 16792 bytes
SHA-256: 9d2294e344127da9ddc2b77d68b1576b6b78373885bc9da2859f180a98f2c1e1
font_01_sfnt_off0000eac7.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xEAC7 10568 bytes
SHA-256: 98900027785f54a97a6e3fa0f1066dccda778be8599fecc4e89a9a720d7674b4
font_02_sfnt_off0001032b.bin pdf-font-stream PDF embedded font (sfnt) at offset 0x1032B 17168 bytes
SHA-256: 4374e5c96fa0274363053cd506955fcd63ef938841cc372ec02f0c4522cbe648

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