Malicious PDF — malware analysis report

Static analysis result for SHA-256 bab4cfb426a2bfc3…

MALICIOUS

PDF

8.3 KB
MD5: 0064788476d4b7f4c41513ced94cf8bf SHA-1: f261ad1afa74a39b73e92dd0527c65f03bffb985 SHA-256: bab4cfb426a2bfc310781e9a64cb1adeb48a3aad983e54f3034708f52ccbf13f
134 Risk Score

Malware Insights

MITRE ATT&CK
T1059.001 PowerShell T1204.002 Malicious File

The PDF file contains heavily obfuscated JavaScript, indicated by multiple heuristic firings including 'PDF_JS_OBFUSCATED_DROPPER' and 'PDF_FROMCHARCODE'. The critical finding 'CVE_2007_5659' points to the exploitation of a known vulnerability to execute arbitrary code. The script's primary function appears to be downloading and executing a second-stage payload, as suggested by the 'PDF_JS_OBFUSCATED_DROPPER' heuristic and the presence of deobfuscated JavaScript files. The exact download URL or payload is not directly discernible due to the obfuscation, but the exploitation primitive 'collab.collectEmailInfo' and the function 'syncAnnotScan' are key indicators of the attack vector.

Heuristics 7

  • Collab.collectEmailInfo — CVE-2007-5659 critical CVE exact CVE_2007_5659
    PDF JavaScript calls Collab.collectEmailInfo — CVE-2007-5659 is a buffer overflow in Adobe Reader triggered by a long argument or heap-sprayed message field passed to Collab.collectEmailInfo(). Part of a series of Acrobat JS API exploits. (identified after JavaScript deobfuscation)
  • Obfuscated multi-stage PDF JavaScript dropper high PDF_JS_OBFUSCATED_DROPPER
    PDF JavaScript shows 3 independent signals of exploit-kit-style multi-stage obfuscation: annot_subject_stage, hex_dashed_payload, 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 4

Files carved from inside the sample during analysis.

FilenameKindSourceSize
javascript_obj0005_000.js
9d5c7e01faed5b04e9ec11f1d98b73f0012c871beaf60e9f9d32ad6df00d46f7
pdf-javascript-stream PDF /JS object 5 at offset 0x148 550 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
f76bab90213aa2512d0c9985f4bf9ae960a9a1228a66149904c82584f196e5cc
deobfuscated-js repeated-marker hex decoded JavaScript at offset 0x1BAC 1921 bytes
Detection
ClamAV: No threats found
Obfuscation or payload: likely
Carved artifact contains 1 eval/decoder/string-building token(s).
legacy_pdfkit_stage_001.js
b160ffb746923cd0c55cf38b70c68972fb6e84a56d2679a04e403ecbac602888
deobfuscated-js annotation-subject callee-key decoded JavaScript at offset 0x359 5135 bytes
Detection
ClamAV: No threats found
Obfuscation or payload: likely
Carved artifact contains 5 eval/decoder/string-building token(s).
deobfuscated.js
476ba711f9a50813c7d74e6c39c73a66d0989d4c1553aa0230075e718738031e
deobfuscated-js PDF JavaScript deobfuscation pass 24372 bytes
Detection
ClamAV: No threats found
Obfuscation or payload: likely
Carved artifact contains 2 eval/decoder/string-building token(s). Carved artifact contains 1 long base64-like blob(s).