putty.exe

by Simon Tatham (Open Source)
Remote Accessmedium risk

Sources: 300M+ executions observed in the wild and observed in the EchoTrail lab on Windows 11.

Summary

PuTTY SSH/Telnet client. Popular open-source terminal emulator for remote access. Also used for SSH tunneling, serial console access, and secure file transfer. Occasionally trojanized and distributed in supply chain attacks.

putty.exe is the 1593rd most commonly executed Windows program in EchoTrail's dataset, observed 585 times across enterprise environments. It typically runs from C:\Program Files\PuTTY and it is most often launched by explorer.exe.

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1593rd
most commonly executed Windows program
585
observed endpoint executions

Behavior

Top Paths

  • C:\Program Files\PuTTY62.22%
  • C:\Program Files (x86)\PuTTY20.17%
  • C:\Users\...14.53%
  • C:\...3.08%

Top Hashes (SHA256)

  • 7afb56dd48565c3c9804f683c80ef47e5333f847f2d3211ec11ed13ad36061e143.14%
  • 567efd7abb99428737d22bf3f8cee9d23a540b4e1565938b557eec54078b8a3112%
  • 9f9e74241d59eccfe7040bfdcbbceacb374eda397cc53a4197b59e4f6f380a9111.91%
  • 8aafc0858cb440910b9b7f237124f373389591a488a77d3d367da56bbf4626787.12%
  • 35c9df3a348ae805902a95ab8ad32a6d61ef85ca8249ae78f1077edd2429fe6b4.95%
  • d4ffa4559a1e22167933772d82cf714cd4bb7a0e79511c2424e18bdb619d63a44.88%
  • 81de431987304676134138705fc1c21188ad7f27edf6b77a6551aa693194485e3.11%
  • f3a88083d28dcd6fa129e8912a8770e5e9987c69ca7b332672bccfbf4ab1ff212.91%
  • abcc2a2d828b1624459cf8c4d2ccdfdcde62c8d1ab51e438db200ab3c5c8cd172.88%
  • 12e2bea20981e4c31e8009be676ae25595a7877d03755126df060ae6336148862.1%
  • 4119bec97bcf2a736f7769d22dc745d8a398a278bd403e53ec2dd2dd0217a6ae

Process Ancestry

Top Grandparents

Top Parents

Top Children

Lab record

Installed from
winget PuTTY.PuTTY 0.84.0.0
Publisher
Simon Tatham
Persistence
none
Network
1 destination
Command lines
2 patterns (2 launches)
DLL loads
53 patterns (89 loads)
Registry writes
3 patterns (15 writes)
File writes
2 patterns (2 writes)
HTTP requests
0 patterns (0 requests)
TLS connections
0 patterns (0 handshakes)
Named pipes
0 patterns (0 events)
Process access
0 patterns (0 events)
Driver loads
0 patterns (0 loads)
PowerShell blocks
0 patterns (0 blocks)
Remote threads
0 patterns (0 events)
Audit events
0 patterns (0 events)

Full record on Team.

Security Analysis

What does putty.exe normally do?

Runs from wherever installed (typically Program Files or user download location). Interactive GUI application for SSH/Telnet connections. Used by IT admins and developers for remote system management.

When is putty.exe suspicious?

PuTTY connecting to unusual external IPs. Running from temp directories or unusual paths. Port forwarding enabled. Running as a background process without UI. Trojanized versions — verify hash against official releases.

How do attackers abuse putty.exe?

1. TUNNELING: Same SSH tunneling capabilities as ssh.exe for C2 and data exfiltration. 2. TROJANIZED DISTRIBUTION: North Korean threat actors (Lazarus) have distributed trojanized PuTTY installers as part of Operation Dream Job, targeting security researchers and developers. 3. CREDENTIAL HARVESTING: PuTTY stores session configurations in the registry (HKCU\Software\SimonTatham\PuTTY) including saved sessions with hostnames — useful for attackers mapping infrastructure.

Detection guidance

MEDIUM-CONFIDENCE: - PuTTY with port forwarding configurations - PuTTY connecting to external IPs outside normal admin patterns - PuTTY hash not matching official release hashes (trojanized) - PuTTY running from temp/download directories DATA SOURCES: Process creation (Sysmon 1), network connections (Sysmon 3), registry access for saved sessions

False positive notes

Extremely common among IT administrators and developers. Many organizations standardize on PuTTY for SSH access to Linux systems.

MITRE ATT&CK techniques

References

Related Processes

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