Ramnit — PDF malware analysis

Static analysis result for SHA-256 e4eefc69d4324b93…

MALICIOUS

PDF

111.2 KB Created: 2016-03-06 12:04:48 +08:00 Authoring application: pdfFactory Pro www.fineprint.cn (via pdfFactory Pro 3.35 (Windows XP Professional Chinese))
MD5: f263ce289887a09ba9174ae7c718752c SHA-1: ce16cd518837a55a1795d3488fc07efbc1bcca32 SHA-256: e4eefc69d4324b9352ae4fb39a9fc59377a5d1593ec4277520474b7d0dae37ab
210 Risk Score

Malware Insights

Ramnit · confidence 95%

MITRE ATT&CK
T1059.001 PowerShell T1204.002 Malicious File T1105 Ingress Tool Transfer

The PDF contains embedded VBScript which reconstructs and executes a PE payload named 'svchost.exe'. This script is designed to download and run a secondary stage, as indicated by the 'PDF_VBS_HEX_PE_DROPPER' heuristic. ClamAV detection confirms the presence of the Ramnit trojan family. The ML classifier also strongly indicates maliciousness.

Machine Learning

  • Nyx PDF Classifier malicious score 0.9975

Heuristics 4

  • VBScript in PDF stream reconstructs and runs a PE payload critical PDF_VBS_HEX_PE_DROPPER
    PDF stream contains an HTML/VBScript block that decodes a long hex string into a Windows executable and runs it via WScript.Shell. This is an embedded dropper payload, not ordinary PDF JavaScript.
  • ClamAV detection on extracted artifact critical EXTRACTED_FILE_CLAMAV
    ClamAV flagged at least one file extracted from inside this sample. Even when the wrapping document carries no AV detection of its own, a hit on the carved artifact is a strong indicator the sample is a delivery vehicle.
  • Embedded script payload in PDF stream high PDF_EMBEDDED_SCRIPT_PAYLOAD
    PDF stream bytes contain script execution markers such as ActiveXObject/CreateObject, WScript.Shell, PowerShell, or shell-exec primitives. This is stronger than ordinary PDF JavaScript because it indicates a staged external script payload hidden in stream bytes.
  • Suspicious extracted artifact medium 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
embedded_vbs_dropper_000002f8.vbs
50b36b292c4a29f5f0d9642bb1487d597e7f817cb538628ff0d791b00e4fac65
pdf-embedded-script PDF raw bytes VBScript dropper at offset 0x2F8 113122 bytes
Detection
ClamAV: No threats found
Obfuscation or payload: likely
Carved artifact contains 1 shell/COM execution token(s). Carved artifact contains 1 long base64-like blob(s).
svchost.exe
fd6c69c345f1e32924f0a5bb7393e191b393a78d58e2c6413b03ced7482f2320
embedded-pe Decoded PE from PDF VBScript dropper at offset 0x2F8 56320 bytes
Detection
ClamAV: Win.Trojan.Ramnit-9775455-0
Obfuscation or payload: likely
Carved artifact entropy is 7.89, consistent with packed or encrypted content.