MalwarePublished 6 Oct 2025Updated 5 Nov 2025

WARMCOOKIE One Year Later: New Features and Fresh Insights

Source AlienVault OTX General

Description

The WARMCOOKIE backdoor continues to evolve, with ongoing updates and new infections observed. Recent developments include new handlers for executing various file types, a string bank for defense evasion, and code optimizations. A campaign ID field has been added, providing context for operators. Infrastructure analysis reveals a default SSL certificate potentially used for WARMCOOKIE back-ends. Despite disruption attempts, the backdoor remains active in malvertising and spam campaigns. The malware's selective usage and continuous updates suggest its persistence as a threat, highlighting the need for enhanced organizational protection measures.

Impact

For European organizations, WARMCOOKIE poses a medium-level threat with potential impacts including unauthorized remote access, data theft, and network compromise. Its stealth features and use of encrypted communications complicate detection, increasing dwell time and potential damage. The malware’s persistence and selective targeting can lead to prolonged unauthorized access, enabling attackers to conduct espionage, exfiltrate sensitive information, or prepare for further attacks such as ransomware deployment. Organizations in sectors heavily targeted by malvertising and spam campaigns, such as finance, healthcare, and government, may face increased risk. The presence of multiple European IP addresses in the malware’s infrastructure suggests active targeting or at least operational presence in Europe. Disruption of business operations, reputational damage, and regulatory penalties under GDPR for data breaches are possible consequences. The malware’s modularity and continuous updates mean that defenses must adapt continuously to new variants and tactics used by operators.

Defensive guidance

1. Implement advanced email filtering solutions capable of detecting and blocking malspam and phishing attempts that may deliver WARMCOOKIE payloads. 2. Deploy web filtering and ad-blocking technologies to reduce exposure to malvertising campaigns. 3. Monitor network traffic for connections to known WARMCOOKIE IP addresses and domains, and block or isolate suspicious communications. 4. Use endpoint detection and response (EDR) tools with behavioral analytics to identify anomalous process executions, especially those involving uncommon file types or suspicious command execution. 5. Regularly update antivirus and anti-malware signatures and employ heuristic and machine learning-based detection to catch evolving variants. 6. Conduct threat hunting exercises focusing on indicators of compromise such as the provided hashes and IP addresses. 7. Enforce strict application whitelisting and least privilege principles to limit the execution of unauthorized code. 8. Educate users on recognizing phishing and suspicious advertisements to reduce the likelihood of initial infection. 9. Maintain robust incident response plans to quickly contain and remediate infections. 10. Investigate the use of SSL/TLS inspection to detect malicious encrypted traffic, considering privacy and legal constraints.

Indicators of compromise

Domains 1

storsvc-win.com

IP addresses 14

87.120.126.32
109.120.137.42
155.94.155.155
185.161.251.26
194.87.45.138
195.82.147.3
38.180.91.117
45.153.126.129
62.60.238.115
85.208.84.220

Hashes 13

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7a799f4f9aa63745a75b901a392aff29
7221b9125608a54f9dd706166f936c16ee23164a
b9983463f637191ba12c2270ac52a547676a7037
e88727d4f95f0a366c2b3b4a742950a14eff04a4
169c30e06f12e33c12dc92b909b7b69ce77bcbfc2aca91c5c096dc0f1938fe76
5bca7f1942e07e8c12ecd9c802ecdb96570dfaaa1f44a6753ebb9ffda0604cb4
8c5522c6f2ca22af8db14d404dbf5647a1eba13f2b0f73b0a06d8e304bd89cc0
9d143e0be6e08534bb84f6c478b95be26867bef2985b1fe55f45a378fc3ccf2b
b7aec5f73d2a6bbd8cd920edb4760e2edadc98c3a45bf4fa994d47ca9cbd02f6

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Description

AI analysisMachine-generated, updated 6 Oct 2025, 11:24 UTC

MITRE ATT&CK techniques8 from threat tags

Technical details

Indicators of compromise

Domains 1

IP addresses 14

Hashes 13

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