Malware

CSTEALER

CSTEALER is a Python-based infostealer advertised with a point-and-click builder. Reported capabilities include theft of browser data, Discord data, and cryptocurrency wallet data, with support for more than 40 wallets. One cited comparison states that CSTEALER’s feature set is nearly identical to Phemedrone’s. It appeared in February 2026 reporting on dark web forum activity as one of several actively marketed or distributed stealer variants within a broader stealer-as-a-service ecosystem. The provided content does not attribute CSTEALER to a specific threat actor, campaign, or victim sector, and does not provide specific indicators of compromise.

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MITRE ATT&CK

Techniques & procedures

4 distinct techniques documented for this family, organized by ATT&CK tactic.

Credential Access

2 techniques

T1539Steal Web Session CookieEvidence1

"Session token and cookie theft has become the primary objective of stealer malware... When attackers steal active session cookies, MFA becomes irrelevant"; and "listings typically include browser passwords, cookies, and session tokens."

T1555.003Credentials from Web BrowsersEvidence1

"Improved decryption of the latest versions of Chromium-based browsers (144+)... Now different versions of Chrome (before 143 / after 144) are decrypted with different elevators, and the method is selected dynamically"; and "listings typically include browser passwords, cookies, and session tokens."

Discovery

1 technique

T1082System Information DiscoveryEvidence1

"detailed system reconnaissance including a screenshot"; and feature lists referencing system info collection

Exfiltration

1 technique

T1567Exfiltration Over Web ServiceEvidence1

"exfiltrates data via Discord webhooks... using Discord’s own webhook infrastructure as free command-and-control channels to exfiltrate stolen data"

ACTIVITY FEED

Recent activity

2 sources tracked across advisories, community write-ups, and news. New activity surfaces here as Mallory finds it.

2 SOURCESView more in app

flareio blogNews

Feb 8, 2026

Inside the Infostealer Arms Race: How Stealer Malware Developers Are Competing to Own the Cybercrime Supply Chain - Flare | Threat Exposure Management | Unmatched Visibility into Cybercrime

Python-based infostealer with a builder; targets Discord account data and extensive browser credential/cookie data plus numerous crypto wallet extensions; uses Discord-focused data theft and is positioned as easy to deploy.

sekoia blogNews

Feb 6, 2024

Adversary C2 infrastructures tracked in 2023 - Sekoia.io Blog

Information stealer distributed via fake video game download websites.

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IOC matching

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Threat actor attribution

Named campaigns wielding this family, with evidence pinned to each claim.

Exploited vulnerabilities

CVEs this family uses for access and lateral movement.

Detection signatures

YARA, Sigma, Snort, and vendor rules, auto-deployed to your SIEM.

MITRE ATT&CK mapping4

Every documented technique, ranked by evidence weight.

Researcher chatter

Reddit, Mastodon, and CTI community discussion around this family.

CSTEALER