Ramnit — PDF malware analysis

Static analysis result for SHA-256 fde5495c1ca617dc…

MALICIOUS

PDF

110.9 KB
MD5: dc5db49fc39e8e42f946c2f97219f6e1 SHA-1: 1ff5d9f5fdcebfaba4c98155dd030f74364a8ed9 SHA-256: fde5495c1ca617dc7beb8d932396d957ab9d70813fc913e359986b544bf231f1
210 Risk Score

Malware Insights

Ramnit · confidence 95%

MITRE ATT&CK
T1059.005 Service Execution: Visual Basic T1204.002 Malicious File: Malicious File T1105 Ingress Tool Transfer

The PDF contains an embedded VBScript that is designed to reconstruct and execute a PE file. The heuristic 'PDF_VBS_HEX_PE_DROPPER' explicitly states this behavior, and the extracted artifact 'svchost.exe' is identified as the dropped payload. The ClamAV signature 'Win.Trojan.Ramnit-9775455-0' strongly suggests the Ramnit family. The VBScript's intent is to download and execute a second-stage payload, which is a common tactic for Ramnit. The confidence is high due to the clear heuristics and specific signature match.

Machine Learning

  • Nyx PDF Classifier malicious score 0.9985

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_00000189.vbs
50b36b292c4a29f5f0d9642bb1487d597e7f817cb538628ff0d791b00e4fac65
pdf-embedded-script PDF raw bytes VBScript dropper at offset 0x189 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 0x189 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.