Malicious RTF / .DOC — malware analysis report

Static analysis result for SHA-256 b7ca78c34ecde019…

MALICIOUS

RTF / .DOC

9.2 KB First seen: 2022-03-22
MD5: 39b97a5764cc7d5f2940c9c756fe24d0 SHA-1: 54e4709bdfe531dde9f004aee34d3e746a3a90b8 SHA-256: b7ca78c34ecde019d8495ffac28c0f3e849aa816a772b80857a9b48b57fbae26
160 Risk Score

Malware Insights

MITRE ATT&CK
T1204.002 Malicious File Execution: Malicious File T1059.001 Command and Scripting Interpreter: PowerShell T1203 Exploitation for Client Execution

The sample is an RTF document that leverages the Equation Editor vulnerability (CVE-2017-11882) to execute arbitrary code. The heuristics indicate the presence of an OLE object with automatic linking and updating, strongly suggesting exploitation. The embedded OLE object data, when decoded, likely contains the exploit code or a loader for a secondary payload.

Heuristics 4

  • 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.
  • Automatically linked OLE object high RTF_OBJAUTLINK
    RTF contains \objautlink — an automatically linked OLE object surface that can be updated or activated when Word opens the document.
  • \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.
  • OLE object data medium RTF_OBJDATA
    RTF contains 2 \objdata section(s) — embedded OLE objects

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
objdata_00_off00001485.bin
6ec830406d5a3f159004d541c64713782001adac6f9a96f728a5ee77ff785c89
rtf-objdata-decoded RTF \objdata at offset 0x1485 1890 bytes