Malicious PDF — malware analysis report

Static analysis result for SHA-256 be9066e9a4f15b50…

MALICIOUS

PDF

118.6 KB
MD5: 0a6c20594493e6049db38d38f6c858c4 SHA-1: 8186b892e23c028b97369831d0a8bb7692033ae0 SHA-256: be9066e9a4f15b50913a185fc8d0d60156b3e1e54a69b2c14f503ccb8428b602
166 Risk Score

Malware Insights

MITRE ATT&CK
T1059.001 PowerShell T1204.002 Malicious Link T1566.001 Spearphishing Attachment

The file is a PDF containing embedded JavaScript, as indicated by multiple PDF-specific heuristic firings including 'PDF_JAVASCRIPT', 'PDF_JS', and 'PDF_EVAL'. The 'PDF_JS_LARGE_COMMENT_PADDED_EVAL' heuristic suggests a stager pattern. ClamAV detection as 'Pdf.Exploit.Agent-36086' confirms its malicious nature. The JavaScript is heavily obfuscated, but the presence of eval() and fromCharCode indicates code execution. The likely intent is to download and execute a second-stage payload.

Heuristics 7

  • ClamAV: Pdf.Exploit.Agent-36086 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Pdf.Exploit.Agent-36086
  • eval() call high PDF_EVAL
    eval() found — commonly used for obfuscated exploit execution (matched inside decoded stream)
  • Large comment-padded JavaScript eval stager high PDF_JS_LARGE_COMMENT_PADDED_EVAL
    PDF JavaScript contains a very large stream padded with long random-looking block comments around String.fromCharCode and eval. This is an exploit-kit obfuscation shape used to bury a decoder and recovered stage inside noise, not normal PDF form automation.
  • JavaScript action low PDF_JAVASCRIPT
    PDF contains a /JavaScript action. Generic JavaScript is common in benign forms; specific dangerous APIs are scored by separate rules.
  • Embedded JS stream low PDF_JS
    PDF references a /JS stream. Generic JavaScript is common in benign forms; specific dangerous APIs are scored by separate rules.
  • String.fromCharCode low PDF_FROMCHARCODE
    String.fromCharCode found — used to construct payload strings dynamically. Common in benign JavaScript libraries for codepoint manipulation, so this alone is informational; weaponised use is also caught by the dedicated fromCharCode-stage and exploit-shape rules. (matched inside decoded stream)
  • Suspicious extracted artifact info EXTRACTED_FILE_STATIC_TRIAGE
    One or more files extracted from inside this sample matched static suspicious-content checks such as script obfuscation, encoded payload blobs, packed data, or execution/download terms.

Extracted artifacts 2

Files carved from inside the sample during analysis.

FilenameKindSourceSize
javascript_obj0006_000.js
4b56c8461c0885f30448984d5bbf15fbb915af8c091fa981d5dafc681a7a7116
pdf-javascript-stream PDF /JS object 6 at offset 0x143 627156 bytes
Detection
ClamAV: No threats found
Obfuscation or payload: likely
Carved artifact contains 2 eval/decoder/string-building token(s). Carved artifact contains 42 long base64-like blob(s).
legacy_pdfkit_stage_000.js
d7ba0a83662af508d76d52fa137b92faaf4397728a49bbbd1d76ec15eaa77d33
deobfuscated-js double percent-decoded annotation JavaScript at offset 0x143 262144 bytes
Detection
ClamAV: No threats found
Obfuscation or payload: likely
Carved artifact contains 506 long base64-like blob(s).