Malicious PDF — malware analysis report

Static analysis result for SHA-256 81c1db594c62f747…

MALICIOUS

PDF

40.3 KB Created: 2020-09-07 13:46:54 +03:00 Authoring application: wkhtmltopdf 0.12.5 (via Qt 4.8.7)
MD5: d3f1d1d23d768e64ad687e65a8d1a57a SHA-1: 76ab022415189f62e2c4206179fd032a0982a5eb SHA-256: 81c1db594c62f747a680ae3569ec86b0a540fe52c1c8c8c3a8c9f6411d31c6d4
174 Risk Score

Malware Insights

MITRE ATT&CK
T1566.001 Spearphishing Attachment

The PDF contains a critical heuristic firing for linking to known malicious redirector infrastructure. Additionally, it exhibits characteristics of a link farm, with numerous embedded URLs pointing to external documents. The ML classifier strongly flagged this PDF as malicious, and the presence of a callback lure suggests a phishing or scam attempt. The primary IOC is the redirector URL, which is likely the initial step in a malicious chain.

Machine Learning

  • Nyx PDF Classifier malicious score 1.0000

Heuristics 5

  • PDF links to known malicious redirector infrastructure critical PDF_MALICIOUS_REDIRECTOR_LINK
    PDF contains a clickable URI to redirector infrastructure used by a known malicious PDF SEO/adware delivery campaign. These documents typically rely on user interaction and redirect chains rather than a PDF parser vulnerability.
  • Small PDF contains mass external PDF link farm critical PDF_SEO_LINK_FARM
    Small PDF contains many clickable external PDF links, mostly clustered on one host. This matches generated SEO/link-farm PDF carriers used to route users into malicious or unwanted-software delivery chains, rather than a normal document citation pattern.
  • Callback phishing phone lure medium SE_CALLBACK_LURE
    Document asks the user to call a phone number in billing, refund, subscription, fraud, or security context — consistent with callback phishing or tech-support scam patterns. Suppressed for legitimate-issuer (IRS/gov/official-form) documents that carry no urgency or charge/dispute escalation.
  • 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://ttraff.link/wix?keyword=azure+pipelines+yaml+templates
    • http://www.ascendercorp.com/
    • http://www.ascendercorp.com/typedesigners.html
    • https://static.usrfiles.com/ugd/cc03df_e7f829c51e9d49cfaf791d3c483a5d11.pdf
    • https://static.usrfiles.com/ugd/225520_b018cb6ab8154c2b92c6f0928cfe2dbd.pdf
    • https://static.usrfiles.com/ugd/d93890_f2fc227987de4030b1ff23368651b196.pdf
    • https://static.usrfiles.com/ugd/fe83c3_23780e5c5c224a849fd249328edd210e.pdf
    • https://cdn.shopify.com/s/files/1/0461/6083/8808/files/convex_mirror_image_formation_ray_diagrams.pdf
    • https://cdn.shopify.com/s/files/1/0431/0096/2967/files/cisco_ons_15454_dwdm_troubleshooting_guide.pdf
    • https://cdn.shopify.com/s/files/1/0434/6360/6422/files/mesivokanevutovuvazidumu.pdf
    • https://cdn.shopify.com/s/files/1/0437/3640/0037/files/automated_guided_vehicles_canada.pdf
    • https://cdn.shopify.com/s/files/1/0436/9488/2984/files/zunufubokawogi.pdf
    • https://cdn.shopify.com/s/files/1/0432/6277/1366/files/maintenance_agreement_template_vosa.pdf
    • https://cdn.shopify.com/s/files/1/0429/4737/9356/files/puwajipegelos.pdf
    • https://static.usrfiles.com/ugd/d1c05f_6eafb23354e44acc90a2edf7e200c398.pdf
    • https://static.usrfiles.com/ugd/0c4177_9d8d03d9b82748528d2d5e304095e405.pdf
    • https://static.usrfiles.com/ugd/5d2cf3_ffd0e873ab7941268253da8b3e9b86c1.pdf
    • https://static.usrfiles.com/ugd/b8c837_785771358b144249a8f55fa1d806eb23.pdf
    • https://static.usrfiles.com/ugd/d4a9d6_ab77ec59b8314250a452e3e0fff31cac.pdf
    • http://www.w3.org/1999/02/22-rdf-syntax-ns#
    • http://purl.org/dc/elements/1.1/
    • http://ns.adobe.com/pdf/1.3/
    • http://ns.adobe.com/xap/1.0/
    • http://ns.adobe.com/xap/1.0/mm/
    • http://ns.adobe.com/xap/1.0/rights/
    • http://scripts.sil.org/OFL

Extracted artifacts 2

Files carved from inside the sample during analysis.

FilenameKindSourceSize
font_00_sfnt_off00005ee7.bin
57a191edc5fa1cf2fd592ed8b331bd72804d33da7bd0463dd9aca17e4489e1ca		 pdf-font-stream PDF embedded font (sfnt) at offset 0x5EE7 5108 bytes
font_01_sfnt_off0000703f.bin
279b01e44feb413fd065ebcda631ca7048e8259cb4ac5ebbc91819a59281bae5		 pdf-font-stream PDF embedded font (sfnt) at offset 0x703F 10616 bytes

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