S1108: PULSECHECK
PULSECHECK is a web shell written in Perl that was used by APT5 as early as 2020 including against Pulse Secure VPNs at US Defense Industrial Base (DIB) companies.[1]
Security context for executives and security teams
S1108: PULSECHECK describes [PULSECHECK](https://attack.mitre.org/software/S1108) is a web shell written in Perl that was used by [APT5](https://attack.mitre.org/groups/G1023) as early as 2020 including against Pulse Secure VPNs at US Defense Industrial Base (DIB) companies.(Citation: Mandiant Pulse Secure Zero-Day April 2021)
Executive priority
S1108: PULSECHECK is an official MITRE ATT&CK software. Glexia treats it as defensive behavior context for prioritizing monitoring, control validation, and response planning without using the object by itself as an attribution claim.
Technical view
Security teams should validate S1108: PULSECHECK by reviewing the official ATT&CK relationships, mapped tactics (the mapped ATT&CK tactic context), supported platforms (Network Devices, Linux), and available local telemetry before making detection or mitigation decisions.
Likely telemetry
- Official ATT&CK relationships and object metadata
- Network, endpoint, and security-tool telemetry
Detection direction
- Validate whether S1108: PULSECHECK appears in your detection coverage and tabletop scenarios.
- Use the object to align executive risk language with SOC, incident response, and detection engineering work.
- Do not treat ATT&CK relationship context as attribution without corroborating evidence.
Mitigation priorities
- Map the object to existing controls and identify missing telemetry or response ownership.
- Prioritize mitigations that reduce exposure on the listed platforms and tactics.
- Review adjacent ATT&CK relationships before changing policy, detections, or reporting language.
Additional notes and limits
Baseline Glexia take generated from the official MITRE ATT&CK STIX object, source hash, tactics, platforms, and detection fields. It is safe to replace with a richer model-generated take for the same source hash later.
This baseline take is source-grounded and schema-validated, but it does not include environment-specific telemetry, incident evidence, or threat-intelligence corroboration.
Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.
PULSECHECK
PULSECHECK is a web shell written in Perl that was used by APT5 as early as 2020 including against Pulse Secure VPNs at US Defense Industrial Base (DIB) companies.[1]
How security teams should use this page
Treat this object as behavior context, not an attribution claim. Validate the related groups, software, data sources, and mitigations against official ATT&CK relationships and your own telemetry before making control-coverage decisions.
Techniques used
This mirrors the MITRE pattern of making group, software, campaign, and technique relationships scannable. Relationship notes come from mirrored ATT&CK relationship text when available.
| Domain | ID | Name | Relationship / procedure |
|---|---|---|---|
| Enterprise | T1071.001 | Web ProtocolsSub-technique | PULSECHECK can check HTTP request headers for a specific backdoor key and if found will output the result of the command in the variable `HTTP_X_CMD.`[1] |
| Enterprise | T1059.004 | Unix ShellSub-technique | PULSECHECK can use Unix shell script for command execution.[1] |
| Enterprise | T1505.003 | Web ShellSub-technique | PULSECHECK is a web shell that can enable command execution on compromised servers.[1] |
| Enterprise | T1132.001 | Standard EncodingSub-technique | PULSECHECK can base-64 encode encrypted data sent through C2.[1] |
Groups, software, and campaigns
G1023: APT5
APT5 is a China-based espionage actor that has been active since at least 2007 primarily targeting the telecommunications, aerospace, and defense industries throughout the U.S., Europe, and Asia. APT5 has displayed advanced tradecraft and significant interest in compromising networking devices and their underlying software including through the use of zero-day exploits.[1][2][3][4][5][6]
All related ATT&CK context
Object version and sync metadata
The fields below describe the current mirrored snapshot. When Glexia retains multiple ATT&CK source imports, you can open the table to compare the same object across releases (hashes and MITRE timestamps). For MITRE’s own release notes and roadmap, see ATT&CK resources — Updates.
Imported snapshots across ATT&CK releases(2)
| Release | Bundle imported | Object version | Modified | Status | Raw hash |
|---|---|---|---|---|---|
| 19.2 | 1.1 | Current bundle | a6b231f3cd64… | ||
| 19.1 | 1.1 | Older bundle | a6b231f3cd64… |
Mirrored ATT&CK source object
The raw object is retained through the mirrored ATT&CK source bundle and object hash. The raw endpoint returns the exact object from the mirrored bundle when available.
External references and citations
MITRE external references are preserved separately from Glexia analysis so citations remain traceable to their original source records.
- [1]Mandiant Pulse Secure Zero-Day April 2021
Perez, D. et al. (2021, April 20). Check Your Pulse: Suspected APT Actors Leverage Authentication Bypass Techniques and Pulse Secure Zero-Day. Retrieved February 5, 2024.
Open source URL - [2]mitre-attackS1108Open source URL
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