CriticalPublic exploit

Backdoor Root Credentials in Xiongmai DVR/NVR/IP Camera Firmware

IdentifiersCVE-2021-41506CWE-798

CVE-2021-41506 affects multiple Xiongmai-based DVR, NVR, and IP camera firmware builds. The provided content states the issue is a backdoor in the macGuarder and dvrHelper binaries caused by static root account credentials embedded in the system. The same supporting material further characterizes this as a debug interface exposed on TCP port 9527 that permits command execution when those default credentials are used. In practice, the vulnerability stems from hard-coded privileged credentials in vendor firmware components, creating an undocumented administrative access path on affected devices.

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ANALYST BRIEF

Impact, mitigation & remediation

What it means. What to do now. Patch path, mitigations, and the assume-compromise checklist.

Impact

What an attacker gets, and what they’ve been doing with it.

Successful exploitation can give an attacker privileged access to the device through the exposed debug service and enable command execution as root or equivalent system-level context. This can allow full compromise of the surveillance device, including arbitrary command execution, configuration manipulation, deployment of follow-on access mechanisms such as telnet, use of the device in botnet activity, and potential pivoting into adjacent networks.

Mitigation

If you can’t patch tonight, do this now.

If a patched firmware image is not available, block external and untrusted internal access to TCP port 9527, disable or restrict management exposure to trusted administration networks only, and place affected devices behind firewalls/VPNs rather than exposing them directly to the internet. Monitor for unexpected access to port 9527 and for signs of post-exploitation activity such as newly opened telnet services or unauthorized command execution. Replace default or static-access pathways where possible and consider device replacement if the vendor cannot provide a fix.

Remediation

Patch, then assume compromise.

Upgrade affected Xiongmai firmware to a vendor-fixed release if one is available for the specific OEM/rebranded device model. Because the issue is rooted in static credentials and a debug interface within firmware components, remediation requires removing or disabling the backdoor mechanism in the affected binaries and eliminating exposure of the port 9527 service. For rebranded devices, obtain firmware only from the device vendor or OEM support channel that explicitly addresses CVE-2021-41506.

PUBLIC EXPLOITS

Exploits

No public exploits tracked yet. Mallory keeps watching.

VALID 0 / 0 TOTALView more in app

No public exploit code observed for this vulnerability.

EXPOSURE SURFACE

Affected products & vendors

Products and vendors Mallory has correlated with this vulnerability. Open in Mallory to drill down to specific CPE configurations and version ranges.

VendorProductType

XiongmaitechAhb7008t-Mh-V2 Firmwareoperating_system

XiongmaitechAhb7804r-Els Firmwareoperating_system

XiongmaitechAhb7804r-Lms Firmwareoperating_system

XiongmaitechAhb7804r-Mh-V2 Firmwareoperating_system

XiongmaitechAhb7808r-Ms Firmwareoperating_system

XiongmaitechAhb7808r-Ms-V2 Firmwareoperating_system

XiongmaitechAhb7808t-Ms-V2 Firmwareoperating_system

XiongmaitechHi3518e 50h10l S39 Firmwareoperating_system

Vendor-confirmed product mapping. Mallory continuously reconciles this list against your asset inventory.

ACTIVITY FEED

Recent activity

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

3 SOURCESView more in app

vulncheck blogNews

Mar 9, 2023

The VulnCheck 2022 Exploited Vulnerability Report - Missing CISA KEV Catalog Entries

Unknown

vulncheck blogNews

Nov 30, 2022

Xiongmai IoT Exploitation

A debug interface on TCP/9527 that permits OS command execution when accessed with default credentials, enabling remote code execution on affected Xiongmai devices.

vulncheck blogNews

Nov 30, 2022

Xiongmai IoT Exploitation

A debug interface on TCP/9527 that permits OS command execution when accessed with default credentials, enabling remote code execution on affected Xiongmai devices.

What this page doesn’t show

The version that knows your environment.

This page is what’s public. Mallory adds the parts that aren’t: which of your assets are affected, which adversaries are exploiting it right now, which detections to deploy, and what to do tonight.

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Exposure mapping

Query your assets running an affected version, and investigate the blast radius.

Threat actor evidence

Every observed campaign linking this CVE to a named adversary.

Associated malware

Malware families riding this exploit, with evidence and IOCs.

Detection signatures

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

Vendor-by-vendor mapping

Cross-references every affected SKU, including bundled OEM variants.

Social activity

Community discussion across Reddit, Mastodon, and other social sources.

EXTERNAL REFERENCES

MITRE CVE

cve.org · CVE-2021-41506

NVD

nvd.nist.gov/vuln/detail/CVE-2021-41506

MITRE CWE · CWE-798

cwe.mitre.org

Vendor Advisory

xiongmaitech.com/en/index.php/news/info/12/68

Third Party Advisory

github.com/Snawoot/hisilicon-dvr-telnet

Third Party Advisory

github.com/tothi/hs-dvr-telnet

Third Party Advisory

habr.com/en/post/486856

Backdoor Root Credentials in Xiongmai DVR/NVR/IP Camera Firmware

IdentifiersCVE-2021-41506CWE-798