Malicious PDF — malware analysis report

Static analysis result for SHA-256 aecf4fb683dcc42e…

MALICIOUS

PDF

72.1 KB Created: 2021-07-13 03:01:32 +03:00 Authoring application: wkhtmltopdf 0.12.5 (via Qt 5.11.3) First seen: 2021-08-25
MD5: 89a4ec7b4dfb3b48f79a1826c67de507 SHA-1: 6f2549bfdd2c6bdc862a7dcbdbb904be72f22435 SHA-256: aecf4fb683dcc42e5ec85fb2eb0375a548ea64c5beb8a50c3d0567e971dd7ec4
136 Risk Score

Malware Insights

MITRE ATT&CK
T1566.001 Spearphishing Attachment

The file is identified as malicious by ClamAV and an ML classifier, with high-severity heuristics indicating it's a phishing lure using an SEO redirector. The embedded URL, https://synerhu.ru/square?utm_term=most+common+adjectives+in+english, is the primary indicator of compromise, likely leading to a malicious site. No scripts were extracted, but the PDF structure and heuristics strongly suggest a phishing attempt.

Machine Learning

  • Nyx PDF Classifier malicious score 0.8216

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
  • 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.
  • 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://synerhu.ru/square?utm_term=most+common+adjectives+in+english PDF link annotation
    • https://static1.squarespace.com/static/60aac4e0d5abe22cec5c4b22/t/60e831d7f4d7c53d8b16ba71/1625829847263/vakuviwuxulexowaxulubopo.pdfIn PDF document text
    • https://static1.squarespace.com/static/60aac4dd19f082755c4e5c69/t/60ec8dd111a746407a421176/1626115538106/designing_a_network_topology.pdfIn PDF document text
    • https://static1.squarespace.com/static/60bf6cad3a95e91b59aa2418/t/60ec912a3080d76c7a51ca33/1626116394449/ankle_pain_after_walking.pdfIn PDF document text
    • https://static1.squarespace.com/static/60aac4dd19f082755c4e5c69/t/60ecc1b9a9c2f82f7833c141/1626128825536/latikevupamimiwet.pdfIn PDF document text
    • https://static1.squarespace.com/static/60bf6cad3a95e91b59aa2418/t/60e945f6f107ff2467ea1c2c/1625900534329/blind_date_mod_sims_4.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_off0000bd0a.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xBD0A 16792 bytes
SHA-256: 9d2294e344127da9ddc2b77d68b1576b6b78373885bc9da2859f180a98f2c1e1
font_01_sfnt_off0000d51c.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xD51C 15160 bytes
SHA-256: 6ef09cc58acaa1003cee029987562c744378d1c4ed8023ce8d697d9e41b8144d
font_02_sfnt_off0000fb9c.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xFB9C 10908 bytes
SHA-256: dcc23c1b54d319967f8b86fb12995abedf2f919bf30abe8ab837834fbaa36961

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