Malicious RTF — malware analysis report

Static analysis result for SHA-256 acef77c2cf69fdc5…

MALICIOUS

RTF

24.1 KB First seen: 2022-12-19
MD5: 85fe9f7db4fca0bee35c93e30424c961 SHA-1: 51fd38274a6bed511f026da1e27ac481b34b758e SHA-256: acef77c2cf69fdc55b1ed34adabcdead5cb9b19b4de6fa9b51efad8d58e86143
140 Risk Score

Malware Insights

MITRE ATT&CK
T1566.001 Spearphishing Attachment T1204.002 Malicious File T1059.005 Visual Basic

The RTF document contains an embedded OLE object with a split Equation Editor ProgID, indicating an attempt to exploit the Equation Editor vulnerability (CVE-2017-11882). The \objupdate directive further suggests that the embedded object is intended to be activated automatically. The heuristic 'SE_ENABLE_LURE' indicates the document likely contains instructions to enable content, a common lure for macro-based malware. The primary goal appears to be the execution of a second-stage 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.
  • \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
  • Macro/content-enable lure medium SE_ENABLE_LURE
    Document instructs the user to enable macros or editing — a common technique used by malware droppers to bypass Office macro security settings

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
objdata_00_off00004db3.bin
f6f375047f8cdc5523ce1381fee289baceb70aab382f9cc4eeae2c5470338f12
rtf-objdata-decoded RTF \objdata at offset 0x4DB3 1346 bytes