Shuyal Stealer has rapidly ascended as one of the most versatile credential theft tools observed in recent months.
First detected in early August 2025, its modular architecture allows it to target an expansive range of web browsers, including Chromium-based, Gecko-based, and legacy engines alike.
Initial indicators of compromise emerged as anomalous network traffic from compromised hosts, where users reported unexplained browser crashes followed by surges in outbound connections to unfamiliar command-and-control (C2) servers.
Point Wild researchers noted that within days of its emergence, Shuyal Stealer had already compromised hundreds of endpoints across multiple industry sectors, including finance, healthcare, and manufacturing.
The malware’s attack vectors are rooted in traditional social engineering techniques, primarily masquerading as software updates or utility installers.
Delivered through phishing emails or malicious advertisements, the installer payload employs a self-extracting archive that unpacks and executes a legitimate system binary alongside an obfuscated DLL loader.
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This side-loading mechanism allows Shuyal Stealer to evade common application whitelist solutions.
As the loader executes, it injects the core stealer module into running browser processes, granting it full access to stored cookies, saved passwords, and form-autofill data.
Point Wild analysts identified the use of encrypted strings and API hashing to conceal calls to key Windows functions such as LoadLibrary and GetProcAddress, complicating static analysis by security researchers.
Upon successful injection, Shuyal Stealer begins its payload routines, harvesting credentials from browser SQLite databases and memory.
It supports 19 different browsers, including Chrome, Edge, Firefox, Opera, Vivaldi, Brave, and several lesser-known forks popular in certain regions.
The stealer can also extract banking session tokens and two-factor authentication approvals stored in local cache.
Once collected, data is compressed using a custom ZIP implementation and encrypted with AES-256 in CBC mode before exfiltration.
Traffic analysis shows the malware batching stolen credentials into 512 KB chunks, which are sent over HTTPS to a dynamically generated subdomain for each victim, complicating takedown efforts.
Infection and Loader Mechanism
Shuyal Stealer’s infection mechanism hinges on DLL side-loading and unhooked API calls to maintain stealth.
After decompressing the archive, the loader writes a benign system executable (for example, svchost.exe) into the Windows directory and drops an accompanying malicious DLL in the same location.
The executable is then launched with a crafted registry entry under HKCUSoftwareMicrosoftWindowsCurrentVersionRun, ensuring persistence across reboots.
Once the legitimate executable loads, Windows automatically resolves and loads the malicious DLL due to its naming convention match.
Within the DLL’s DllMain, the loader invokes a staged unpacker:-
// Simplified unpack routine
void UnpackAndInject() {
BYTE* encryptedPayload = LoadResource(MAKEINTRESOURCE(101));
BYTE* payload = DecryptAES256(encryptedPayload, payloadSize, key, iv);
HANDLE hProc = OpenProcess(PROCESS_ALL_ACCESS, FALSE, targetPid);
LPVOID remoteMem = VirtualAllocEx(hProc, NULL, payloadSize, MEM_COMMIT, PAGE_EXECUTE_READWRITE);
WriteProcessMemory(hProc, remoteMem, payload, payloadSize, NULL);
CreateRemoteThread(hProc, NULL, 0, (LPTHREAD_START_ROUTINE)remoteMem, NULL, 0, NULL);
}This unpacker decrypts the core stealer module in memory and injects it into the target browser process.
By avoiding writing the primary payload to disk and leveraging legitimate binaries, Shuyal Stealer bypasses many endpoint detection solutions.
The use of API hashing further thwarts heuristic detection, as function names never appear in string tables.
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