Malicious RTF — malware analysis report

Static analysis result for SHA-256 dd0177edfb4b4ee8…

MALICIOUS

RTF

2.49 MB First seen: 2021-10-31
MD5: 3e0f8f79da56438de9d76e90ee2fb166 SHA-1: 560ac6fd9166583a48442647425c596e74fd8af2 SHA-256: dd0177edfb4b4ee8f02ec0e7f02a20170305cc52f5da984e687583f3b90de28b
222 Risk Score

Malware Insights

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

The RTF file contains an embedded OLE object that exploits CVE-2017-11882, a known vulnerability in Microsoft Equation Editor. This exploit is designed to execute arbitrary code, likely downloading and running a secondary malicious payload. The presence of large, high-entropy hex data within the OLE object further supports the conclusion that it contains a hidden executable.

Heuristics 6

  • Equation Editor OLE1 native payload — CVE-2017-11882 related critical CVE related CVE_2017_11882_RELATED
    RTF decodes to an OLE1 Equation.3 embedded object whose native data is large and payload-like, and \objupdate requests automatic activation. This is the delivery shape used by Equation Editor RCE documents such as CVE-2017-11882/CVE-2018-0802, but the malformed MTEF record needed for exact attribution was not recovered.
  • Split hex Equation Editor ProgID + OLE object critical 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.
  • \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.
  • Large hex data blocks in OLE object high RTF_EXCESSIVE_HEX
    RTF contains ~2604KB of hex-encoded data inside \objdata sections — may hide a payload
  • OLE object data medium RTF_OBJDATA
    RTF contains 2 \objdata section(s) — embedded OLE objects
  • 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 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
objdata_00_off00001a20.bin rtf-objdata-decoded RTF \objdata at offset 0x1A20 1302386 bytes
SHA-256: 46c8ed6a04825abf5ca7ea4d1019ff7109988e20993caeafc4aa7e3a3ddd323a
Detection
ClamAV: No threats found
Obfuscation or payload: likely
Carved artifact entropy is 7.99, consistent with packed or encrypted content.