Malicious PDF — malware analysis report

Static analysis result for SHA-256 78deaf3b40eeabf3…

MALICIOUS

PDF

8.3 KB
MD5: f16bfef588115b5204df2adffaa6b349 SHA-1: cee2f360a1d73fb3659b2a1f7dd56503c17a55c9 SHA-256: 78deaf3b40eeabf37c0abb06217a1e5d2db2f078c86bbf675f0d0a88da168356
196 Risk Score

Malware Insights

MITRE ATT&CK
T1059.001 PowerShell T1204.002 Malicious File T1071.001 Web Protocols

The PDF file contains obfuscated JavaScript, identified as a multi-stage dropper. This script leverages the CVE-2007-5659 vulnerability, specifically using the `Collab.collectEmailInfo` function to execute a decoded payload. The primary function of the script is to download and execute additional malicious content, indicated by the 'dropper' heuristic. The presence of multiple deobfuscated JavaScript files further supports the multi-stage nature of the attack.

Heuristics 8

  • 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)
  • ClamAV: Pdf.Dropper.Agent-7274725-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Pdf.Dropper.Agent-7274725-0
  • 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
ab3f4be7a3e2e879e844dcace56ca59cf8fe7249dc5a05c90896f0c9e7dd732a
pdf-javascript-stream PDF /JS object 5 at offset 0x148 559 bytes
Detection
ClamAV: No threats found
Obfuscation or payload: likely
Carved artifact contains 2 eval/decoder/string-building token(s).
legacy_pdfkit_stage_000.js
bd2f007881126aba6197046258e6a7cf33e0ebd55d93943b630b53f0da99b5c4
deobfuscated-js repeated-marker hex decoded JavaScript at offset 0x1BC6 1907 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
7ccc5582b6a75996a6c5a27076e2d212c7a4eb5cb36c40902def9a5c03cd1e4a
deobfuscated-js annotation-subject callee-key decoded JavaScript at offset 0x374 5256 bytes
Detection
ClamAV: No threats found
Obfuscation or payload: likely
Carved artifact contains 5 eval/decoder/string-building token(s).
deobfuscated.js
a3c68fc60ce184ccc2925e60d4128a0e0304aa6b442f08744b35e965f258206b
deobfuscated-js PDF JavaScript deobfuscation pass 24396 bytes
Detection
ClamAV: No threats found
Obfuscation or payload: likely
Carved artifact contains 4 eval/decoder/string-building token(s). Carved artifact contains 1 long base64-like blob(s).