Malicious PDF — malware analysis report

Static analysis result for SHA-256 ac89cb5b41058c2c…

MALICIOUS

PDF

15.7 KB
MD5: 7c4be36405a2ea083dbc86b4e22f4a22 SHA-1: efe585a2390c663a343ffb4a442d224e967c535d SHA-256: ac89cb5b41058c2c0b103d402e11c50008b9b25b963530bffdd312162a59e9e5
166 Risk Score

Malware Insights

MITRE ATT&CK
T1059.001 PowerShell T1204.002 Malicious File T1566.001 Spearphishing Attachment T1027 Obfuscated Files or Information

This PDF file contains embedded JavaScript that utilizes eval() and String.fromCharCode, indicating obfuscation and dynamic code execution. The 'Large comment-padded JavaScript eval stager' heuristic strongly suggests the script is designed to download and execute a second-stage payload. The ClamAV detection of 'Pdf.Exploit.Agent-36086' further confirms its malicious nature, pointing towards a known exploit or malware dropper.

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
40d0adb37e68ef5d37e1658568606abb424426dceee40d6d0ac7355c83da6dd2
pdf-javascript-stream PDF /JS object 6 at offset 0x143 424567 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).
stream_001_off00003b58.bin
2c041fd0a4ebaee8fc3bfec09b96f4d4e3e6772f56eee4600b59b71bc7a2e936
decompressed-pdf-stream PDF FlateDecoded stream at offset 0x3B58 300 bytes