Malicious RTF — malware analysis report

Static analysis result for SHA-256 e5e247ec942e7776…

MALICIOUS

RTF

1.79 MB First seen: 2021-07-13
MD5: 154ef9852577be314e65263e0f11c46e SHA-1: 138e10a308608dfb8c75e3749afb3d9e1defc2f5 SHA-256: e5e247ec942e77762120486c7c5b3dd2f4c600f9ca70037ddf4e5d99d5126806
220 Risk Score

Malware Insights

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

The RTF file contains multiple indicators of malicious activity, including OLE object data and specific heuristics pointing to the Equation Editor vulnerability (CVE-2017-11882). This vulnerability is known to be exploited for client execution, likely to deliver a secondary payload. The presence of decoded object data further supports the exploitation of this known vulnerability.

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 61483 bytes
SHA-256: 21dbb88757330d7cbb2bf7f485b2b4c262be5cad1100556936920e279fc76157
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_off00034cd0.bin rtf-objdata-decoded RTF \objdata at offset 0x34CD0 453383 bytes
SHA-256: 4d6664f118eedff717160ab4a66190ef5c19c482cce6369b56962aafb643a777