Malicious PDF — malware analysis report

Static analysis result for SHA-256 2c1389cf857e6afc…

MALICIOUS

PDF

7.9 KB
MD5: 211bcb8f633c6bd6ad0394b9efdd695c SHA-1: 13d02f924bb7c86ea560d17c5e067d984acf073e SHA-256: 2c1389cf857e6afc932b52bf894c6d3531f78683a95e6b70dd31f126093636e1
134 Risk Score

Malware Insights

MITRE ATT&CK
T1059.001 PowerShell

The PDF contains heavily obfuscated JavaScript, identified as a multi-stage dropper. Analysis of the embedded JavaScript streams indicates that the script decodes a payload, likely from an annotation subject, and then executes it. This behavior is consistent with a dropper designed to download and run further malicious content. The ClamAV detection of 'Pdf.Exploit.Agent-35902' further confirms its malicious nature.

Heuristics 7

  • ClamAV: Pdf.Exploit.Agent-35902 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Pdf.Exploit.Agent-35902
  • Obfuscated multi-stage PDF JavaScript dropper high PDF_JS_OBFUSCATED_DROPPER
    PDF JavaScript shows 5 independent signals of exploit-kit-style multi-stage obfuscation: annot_subject_stage, hex_codec_loop, hex_dashed_payload, incremental_eval_build, repeated_pluginschk. This is strongly consistent with pre-2011 Adobe Reader PDF droppers — OpenAction JS reads encoded data from annotation subjects, decodes it through one or more hex / base-N loops, and invokes eval indirectly (method name built one character at a time). The actual CVE is hidden in the final decoded layer and is not visible via static analysis.
  • 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)
  • syncAnnotScan annotation-staging primitive low PDF_FOXIT_SYNCANNOTSCAN
    PDF JavaScript calls syncAnnotScan() — a no-op annotation-enumeration primitive used by exploit-kit JavaScript to stage payload reads from annotation /Subject fields before eval(). Not a vulnerable sink itself; rarely seen in legitimate PDFs. (matched in decompressed 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 3

Files carved from inside the sample during analysis.

FilenameKindSourceSize
javascript_obj0005_000.js
3cf6a22459cda11e607fc9e0dc0c88d01a8425e26488ff87df38d855ceb4dccf
pdf-javascript-stream PDF /JS object 5 at offset 0x148 465 bytes
Detection
ClamAV: No threats found
Obfuscation or payload: likely
Carved artifact contains 1 eval/decoder/string-building token(s).
legacy_pdfkit_stage_000.js
501b99a842dcd59c9469af9f6575bbdc01d8602fa07bc50c0a495e1dd89f9903
deobfuscated-js repeated-marker hex decoded JavaScript at offset 0x1AB4 1659 bytes
Detection
ClamAV: No threats found
Obfuscation or payload: likely
Carved artifact contains 1 eval/decoder/string-building token(s).
deobfuscated.js
1ed118d22c01a292056beaad4d2cb48469db866ffe786e5ea153cea67ee2d38b
deobfuscated-js PDF JavaScript deobfuscation pass 21531 bytes
Detection
ClamAV: No threats found
Obfuscation or payload: likely
Carved artifact contains 5 eval/decoder/string-building token(s). Carved artifact contains 1 long base64-like blob(s).