Malicious RTF — malware analysis report

Static analysis result for SHA-256 8a5303205c0a821b…

MALICIOUS

RTF

216.8 KB First seen: 2019-05-16
MD5: 55b25e71f4035ebbb09369279c6d3a40 SHA-1: d9bfc1b57c7321fe5cd40084c9970b0bc978c04d SHA-256: 8a5303205c0a821bb745c30520e56d5c8f9db6fd6ee6c18d55cc28abc65d7a75
120 Risk Score

Malware Insights

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

The sample is an RTF document containing an embedded OLE object that exploits a known vulnerability in the Equation Editor component. The presence of RTF_EQUATION_EDITOR and RTF_OBJUPDATE heuristics indicates an attempt to trigger code execution. The RTF_OBJDATA heuristic confirms the presence of embedded object data, which is likely used to deliver the exploit. The primary attack vector is likely spearphishing, with the embedded exploit serving to download and execute a secondary payload.

Heuristics 3

  • 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.
  • \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 1 \objdata section(s) — embedded OLE objects

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
objdata_00_off00030eaa.bin rtf-objdata-decoded RTF \objdata at offset 0x30EAA 2191 bytes
SHA-256: 15becfaefb7200db1e850a5738d1a620da2623afbe95d32ae265b1e66fafeb8a