DRYHOOK

S9013

Malware.View on attack.mitre.org

About this malware

DRYHOOK is Python script used to steal credentials. DRYHOOK was first reported in January 2025, and has previously been leveraged by People's Republic of China (PRC) state-affiliated threat actors identified as UNC5221 and SYLVANITE.

Techniques used11

Procedure examples11

TechniqueProcedure example
T1027.013
Encrypted/Encoded File

DRYHOOK has encrypted stolen credentials strings within a file using both Base64 and RC4 with a hard-coded key.

T1056.001
Keylogging

DRYHOOK has captured user credentials and passwords in plaintext and has encrypted them in a stored file on the network device.

T1059.006
Python

DRYHOOK is a Python-based script that executes within the victim environment.

T1059.008
Network Device CLI

DRYHOOK has the ability to interact with Ivanti Connect Secure environments and to modify system components.

T1074.001
Local Data Staging

DRYHOOK has stored stolen credentials for future use in the temp folder of a victimized Ivanti Connect Secure VPN device, specifically in the file location `/tmp/cmmmap.kumMW`.

T1222.002
Linux and Mac Permissions

DRYHOOK has the ability to remount the filesystem as “read-write” to make changes and then restores it to “read-only” prior to killing processes to apply the modifications.

T1489
Service Stop

DRYHOOK has terminated all instances of the `cgi-server` process before activating the modified DSAuth.pm file.

T1556
Modify Authentication Process

DRYHOOK has intercepted and logged user credentials by modifying the Perl module in Ivanti Connect Secure VPN edge-devices located within `/home/perl/DSAuth.pm`.

T1556.004
Network Device Authentication

DRYHOOK has patched victim appliances authentication routines to capture credentials in plaintext as users log in.

T1601
Modify System Image

DRYHOOK has modified the Ivanti Connect Secure VPN authentication Perl module `DSAuth.pm` by reading its contents in the buffer, then finding and replacing select lines of code.

T1685
Disable or Modify Tools

DRYHOOK has killed all instances of the `cgi-server` process in order for the modified Perl module to be activated.

Groups that use it0

None recorded.

Campaigns0

None recorded.

References3

  1. Dragos SYLVANITE MuddyWater Electrum March 2026 Open source
    Dragos. (2026, March 24). Dragos 2026 OT Cybersecurity Report: Year in Review, O&G and Petrochemicals Focus. Retrieved April 17, 2026.
  2. Google UNC5221 Ivanti January 2025 Open source
    John Wolfram, Josh Murchie, Matt Lin, Daniel Ainsworth, Robert Wallace, Dimiter Andonov, Dhanesh Kizhakkinan, Jacob Thompson. (2025, January 8). Ivanti Connect Secure VPN Targeted in New Zero-Day Exploitation. Retrieved April 14, 2026.
  3. Picus Security UNC5221 Ivanti May 2025 Open source
    Sila Ozeren Hacioglu. (2025, May 5). UNC5221’s Latest Exploit: Weaponizing CVE-2025-22457 in Ivanti Connect Secure. Retrieved April 13, 2026.

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