Malicious RTF — malware analysis report

Static analysis result for SHA-256 a7d361e5232d6d33…

MALICIOUS

RTF

1.77 MB First seen: 2021-07-10
MD5: 2ffc7e13a9ba53e46217edd49c287b8e SHA-1: 263619eabc83a8e335d3ef69450a75a059f7d257 SHA-256: a7d361e5232d6d33dc4d69cf6b7831c9bdac33c68cbd91187610706c25041ea9
220 Risk Score

Malware Insights

MITRE ATT&CK
T1203 Exploitation for Client Execution T1566.001 Spearphishing Attachment

The RTF file contains embedded OLE objects, specifically triggering heuristics related to Equation Editor and CVE-2017-11882. The presence of shellcode command strings within an extracted artifact further indicates the execution of a malicious payload. The exploit likely serves as a delivery mechanism for a secondary stage, commonly seen in phishing attacks.

Heuristics 6

  • Split hex Equation Editor ProgID + OLE object critical CVE likely RTF_EQUATION_EDITOR
    RTF embeds the Equation.3 ProgID as hex bytes near OLE object activation and splits the byte stream with whitespace or an ignorable RTF group. This is an Equation Editor OLE activation surface commonly used by CVE-2017-11882 / CVE-2018-0802 exploit documents.
  • Equation Editor activation — CVE-2017-11882 related high CVE related CVE_2017_11882_ACTIVATION_RELATED
    RTF decodes to an Equation.3 ProgID and requests OLE activation with \objemb plus \objupdate. This reaches the legacy Equation Editor attack surface used by CVE-2017-11882/CVE-2018-0802 documents, but the malformed MTEF/native payload needed for stronger attribution was not recovered.
  • \objupdate forces OLE activation high RTF_OBJUPDATE
    RTF contains \objupdate — forces automatic OLE object instantiation when the document is opened, bypassing user interaction. Almost exclusively seen in Equation Editor exploit documents.
  • Suspicious extracted artifact high 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.
  • OLE object data medium RTF_OBJDATA
    RTF contains 2 \objdata section(s) — embedded OLE objects
  • Embedded OLE object medium RTF_OBJEMB
    RTF contains \objemb — embedded OLE object

Extracted artifacts 2

Files carved from inside the sample during analysis.

FilenameKindSourceSize
objdata_00_off000011e1.bin rtf-objdata-decoded RTF \objdata at offset 0x11E1 53758 bytes
SHA-256: cbf6d09d18182b76b153100c51f18a0f9e671c9de980136d17dff950aeb593f5
Detection
ClamAV: No threats found
Obfuscation or payload: likely
Static shellcode analysis recovered command string(s): WScript.ScriptName, WScript.Quit(), Cmd = strActivationID(""" ypoc c/ dmc") & sKeys & WScript.ScriptName & """ """ & lValue & """ /Y"
objdata_01_off0002fc2f.bin rtf-objdata-decoded RTF \objdata at offset 0x2FC2F 453383 bytes
SHA-256: e1f744f201031a94b7338c99efa7dc221d6af19e0163291dabfeddbdf7cb992f