WSO
WSO is a PHP web shell used by attackers to obtain persistent remote access to compromised web servers. In the provided content, WSO is repeatedly identified as an uploaded post-exploitation payload in attacks against Adobe Commerce and Magento Open Source environments, including exploitation of CVE-2025-54236 and CVE-2024-34102 (SessionReaper). After successful exploitation, attackers upload variants of WSO into web-accessible directories or the webroot, where it is used to enumerate the environment, execute commands, steal configuration data such as database credentials and API keys, facilitate data theft, and maintain persistence. The content also notes follow-on activity including privilege escalation, creation of administrative accounts, disabling of security plugins, customer account hijacking, order manipulation, and exfiltration of PII in affected Magento environments. WSO is also referenced in shell-finder reconnaissance activity, where threat actors search for known backdoor filenames to locate already-compromised websites; listed filenames include wso.php, wso1.php, wso2.8.5.php, wp-admin/wso32.php, and FoxWSO-full.php. High-confidence indicators mentioned in the content include unauthorized files in web-accessible directories, anomalous POST requests to /customer/address_file/upload in the CVE-2025-54236 campaign, and the presence of known WSO-related filenames on disk.
Hunt this family in your stack
Mallory pivots from this family to the IOCs, detections, and named campaigns that touch your stack, and pages you when something new lands.
Vulnerabilities exploited
2 CVEs Mallory has correlated with this family across public research and vendor advisories. Each row links to the full Mallory page for that vulnerability.
This enables the upload of persistent PHP webshells, such as variants of WSO and b374k, granting attackers full remote access to the underlying server. | The exploited vulnerability, CVE-2025-54236, is a critical improper input validation and nested deserialization flaw in the Adobe Commerce and Magento Open Source REST API, specifically affecting the /customer/address_file/upload endpoint.
The SessionReaper vulnerability (CVE-2024-34102) arises from improper input validation and insecure session management within the Adobe Magento REST API. Specifically, the flaw allows an attacker to craft malicious API requests that manipulate session data stored on the server’s file system... | If successful, the attacker can inject malicious PHP code or directly upload webshells, such as variants of WSO, C99, or custom lightweight shells, into the webroot.
Groups observed using it
1 distinct threat actor attributed by public researchers. Open in Mallory to see the full evidence chain and overlapping campaigns.
"...upload webshells, such as variants of WSO, C99, or custom lightweight shells, into the webroot."
Techniques & procedures
7 distinct techniques documented for this family, organized by ATT&CK tactic.
Initial Access
1 techniqueThe exploited vulnerability, CVE-2025-54236, is a critical improper input validation and nested deserialization flaw in the Adobe Commerce and Magento Open Source REST API, specifically affecting the /customer/address_file/upload endpoint.
Execution
1 techniqueIf successful, the attacker can inject malicious PHP code or directly upload webshells, such as variants of WSO , C99 , or custom lightweight shells, into the webroot.
Persistence
1 techniqueThis enables the upload of persistent PHP webshells, such as variants of WSO and b374k, granting attackers full remote access to the underlying server.
Credential Access
2 techniquesSuccessful exploitation results in the deployment of a webshell, which is then used to enumerate the environment, extract sensitive configuration data (including database credentials and API keys), and establish additional persistence mechanisms.
Attackers craft malicious serialized payloads that, when processed by the vulnerable API, result in arbitrary PHP object instantiation and code execution.
Discovery
1 techniqueSuccessful exploitation results in the deployment of a webshell, which is then used to enumerate the environment, extract sensitive configuration data (including database credentials and API keys), and establish additional persistence mechanisms.
Command and Control
1 techniqueRelevant MITRE ATT&CK techniques include T1190 (Exploit Public-Facing Application), T1505.003 (Web Shell), and T1071.001 (Web Protocols for C2 communication).
IOCs tracked for this family
5 indicators attributed across vendor reports, sandbox runs, and researcher write-ups. Full values are available in Mallory.
IPs, domains, and DNS infrastructure linked to this family.
Recent activity
3 sources tracked across advisories, community write-ups, and news. New activity surfaces here as Mallory finds it.
A PHP web shell used to provide persistent remote access and command execution on compromised web servers.
A PHP webshell used to provide persistent remote access to compromised servers, enabling post-exploitation activity such as environment enumeration, data extraction, and persistence.
A web shell/backdoor family commonly deployed on compromised websites to maintain unauthorized access and later discovered by shell finder tools.
The version that knows your environment.
Match every observed IP, domain, and hash against your live telemetry.
Named campaigns wielding this family, with evidence pinned to each claim.
CVEs this family uses for access and lateral movement.
YARA, Sigma, Snort, and vendor rules, auto-deployed to your SIEM.
Every documented technique, ranked by evidence weight.
Reddit, Mastodon, and CTI community discussion around this family.