Malicious PDF — malware analysis report

Static analysis result for SHA-256 163b53ec6d9a62fb…

MALICIOUS

PDF

66.2 KB Created: 2021-04-18 21:02:25 +03:00 Authoring application: wkhtmltopdf 0.12.5 (via Qt 4.8.7) First seen: 2021-10-24
MD5: c675172a9f242cd535280de91f9d9dd8 SHA-1: 00c7bfcd83d2feb69ba4313d2652598130995c38 SHA-256: 163b53ec6d9a62fbc3e249a72e85aed02bae15e50c977797da1823ee75cc28d7
146 Risk Score

Malware Insights

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

The PDF contains numerous embedded URLs, many of which point to disposable domains or are part of link farms, indicating a phishing or redirection attempt. The ML classifier and ClamAV detection strongly suggest malicious intent. While no scripts were explicitly extracted, the malformed stream length and embedded URI heuristics point to exploit activity within the PDF structure, likely leading to the download or redirection to malicious content.

Machine Learning

  • Nyx PDF Classifier malicious score 0.9998

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
  • Malformed active-content stream length medium PDF_MALFORMED_EXPLOIT_STREAM_LENGTH
    A PDF stream that carries active/exploit-looking content has a declared /Length that does not match the recovered stream body. Malformed stream boundaries and length mismatches are common parser-evasion/supporting evidence around Reader exploit streams.
  • 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://ambrose.edu/sites/default/files/webform/gewematumupam.pdf In PDF document text
    • http://www.friendlycc.com/sites/default/files/webform/16921441106.pdfIn PDF document text
    • http://www.sumnercountyhospital.org/sites/default/files/webform/72664382884.pdfIn PDF document text
    • https://ambrose.edu/sites/default/files/webform/tinijozude.pdfIn PDF document text
    • https://www.mothercare.ro/sites/default/files/webform/resumes/tizagoge.pdfIn PDF document text
    • https://ambrose.edu/sites/default/files/webform/seliruni.pdfIn PDF document text
    • https://www.ofalloncasting.com/sites/default/files/webform/zuloliresu.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/1eyvgo/aqOO/~3/FevRqgeaUVY/uplcv?utm_term=digital+communication+proakisPDF link annotation
    • https://ubmemeaensoprod.s3.amazonaws.com/ifsec_international/call_for_papers/2021/03/wutiladerotegedubel.pdfIn PDF document text
    • https://community.princeton.edu/system/files/webform/4167827641.pdfIn PDF document text
    • https://www.vub.be/sites/vub/files/webform/siwujomizawafoxewop.pdfIn PDF document text
    • https://www.ice.cam.ac.uk/sites/www.ice.cam.ac.uk/files/webform/ruwitik.pdfIn PDF document text
    • https://minorsoncampus.princeton.edu/system/files/webform/fujixedapilevunagujos.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_off0000c500.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xC500 5316 bytes
SHA-256: 05f0045405264940f5c0876f4c6a0b46d3b9215d298805c9804552258cce6ab7
font_01_sfnt_off0000d709.bin pdf-font-stream PDF embedded font (sfnt) at offset 0xD709 10528 bytes
SHA-256: 48914dd21e6123601f2614a5c67bc6176334d5d605b523cd76f3102fa66a8731

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