Malicious PDF — malware analysis report

Static analysis result for SHA-256 079823c331ec433e…

MALICIOUS

PDF

80.3 KB Created: 2021-04-26 15:04:28 +03:00 Authoring application: wkhtmltopdf 0.12.5 (via Qt 4.8.7)
MD5: 2ac08454b7ae1077923c637ee373d597 SHA-1: 922e04ee80f8bbbd76be02a8f0163bec36aad5f2 SHA-256: 079823c331ec433e20af4ca806b4d6ed910c1ab17cefe6823e92d8ddfa421f15
156 Risk Score

Malware Insights

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

The PDF file was detected as malicious by ML classifiers and ClamAV, specifically flagged as a phishing trojan. It contains a large number of external links, with one prominent URL pointing to a suspicious domain and another to a PDF file on AWS, suggesting a link farm or redirection mechanism. The document body, though heavily obfuscated, contains references to 'wkhtmltopdf' and 'common core sheets finding elapsed time', which appear to be lures to encourage users to click on the embedded links.

Machine Learning

  • Nyx PDF Classifier malicious score 0.9998

Heuristics 5

  • 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.
  • ClamAV: Pdf.Phishing.Trojan-d2568dad23a94d95-d2568dad23a94d95-10044375-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Pdf.Phishing.Trojan-d2568dad23a94d95-d2568dad23a94d95-10044375-0
  • 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://nipisod.ru/strik?utm_term=common+core+sheets+finding+elapsed+time
    • https://static.s123-cdn-static.com/uploads/4406820/normal_5fca5dff24b77.pdf
    • https://cdn-cms.f-static.net/uploads/4417321/normal_606443bdd8b84.pdf
    • https://cdn-cms.f-static.net/uploads/4456712/normal_60432a5b5c3fc.pdf
    • https://cdn-cms.f-static.net/uploads/4491412/normal_6032152c2789a.pdf
    • https://cdn.sqhk.co/fexiseme/fV7A7kY/my_airtel_prepaid_login_call_details.pdf
    • https://cdn-cms.f-static.net/uploads/4380084/normal_6069978a43f94.pdf
    • https://cdn-cms.f-static.net/uploads/4413578/normal_605e03c334e00.pdf
    • https://static.s123-cdn-static.com/uploads/4453329/normal_5ffb21ac48dec.pdf
    • https://cdn.sqhk.co/zubejavaxuvu/bqYiCMN/nerokezusizasupanobim.pdf
    • https://cdn-cms.f-static.net/uploads/4420039/normal_5fe9b9ab93a21.pdf
    • https://cdn-cms.f-static.net/uploads/4469103/normal_603d0f4c881d0.pdf
    • https://cdn-cms.f-static.net/uploads/4420905/normal_60314d638a179.pdf
    • https://static.s123-cdn-static.com/uploads/4480750/normal_5fcb3315d659f.pdf
    • http://www.ascendercorp.com/
    • http://www.ascendercorp.com/typedesigners.html
    • https://s3.amazonaws.com/kovibu/xugebu.pdf
    • https://0bef8565-087b-457a-960c-b0529baba50c.filesusr.com/ugd/638000_1e9e081680784450a17663b8f5d7be5a.pdf?index=true
    • https://s3.amazonaws.com/getizar/31635171763.pdf
    • https://56076a71-1b70-41e8-afe1-d547c394b4ee.filesusr.com/ugd/ab0d05_893201b59722482f8e32ad0e042f54f0.pdf?index=true
    • 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_off0000fb60.bin
3c61d2e7143c273e0e4158597bc5b675674f6df4714730f0e63be5b8c62e0e88		 pdf-font-stream PDF embedded font (sfnt) at offset 0xFB60 5476 bytes
font_01_sfnt_off00010dd3.bin
cdd2729002634cd1ac753d43b7bf12feaa5c985968d2e5902ba841d1fc976cf9		 pdf-font-stream PDF embedded font (sfnt) at offset 0x10DD3 10780 bytes

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