CyberSecBulletin
CVE-2020-5735Exploited in the wildNVD status: Analyzed

Amcrest Cameras and NVR Stack-based Buffer Overflow

Published Updated By the CyberSecBulletin desk

CVE-2020-5735 is a high-severity out-of-bounds write vulnerability in Amcrest, with a CVSS 3.1 base score of 8.8 out of 10. It can be exploited remotely over the network by an attacker with a low-privileged account, without any action from a user. CISA added it to the Known Exploited Vulnerabilities catalogue on November 3, 2021, which means attacks have been observed in the wild.

Patch now

Attackers are already exploiting this vulnerability, according to CISA.

What to do

  1. Update Ipm-721 Firmware to v2.420.ac00.18.r.20200217 or a later version.
  2. Update Ip2m-841 Firmware to v2.420.ac00.18.r.20200217 or a later version.
  3. Update Ip2m-841-v3 Firmware to v2.800.0000000.6.r.200314 or a later version.
  4. CISA's required action: Apply updates per vendor instructions.

Affected products and versions

VendorProductAffected versionsFixed in
AmcrestAmcrestNot specified in the recordNot stated
Amcrest1080-lite 8ch FirmwareNot specified in the recordNot stated
AmcrestAmdv10814-h5 FirmwareNot specified in the recordNot stated
AmcrestIpm-721 Firmwarebefore v2.420.ac00.18.r.20200217v2.420.ac00.18.r.20200217
AmcrestIp2m-841 Firmwarebefore v2.420.ac00.18.r.20200217v2.420.ac00.18.r.20200217
AmcrestIp2m-841-v3 Firmwarebefore v2.800.0000000.6.r.200314v2.800.0000000.6.r.200314
AmcrestIp2m-853ew Firmwarebefore v2.623.00ac004.0.r.200316v2.623.00ac004.0.r.200316
AmcrestIp2m-858w Firmwarebefore v2.623.00ac004.0.r.200316v2.623.00ac004.0.r.200316
AmcrestIp2m-866w Firmwarebefore v2.623.00ac004.0.r.200316v2.623.00ac004.0.r.200316
AmcrestIp2m-866ew Firmwarebefore v2.623.00ac004.0.r.200316v2.623.00ac004.0.r.200316
AmcrestIp4m-1053ew Firmwarebefore v2.623.00ac004.0.r.200316v2.623.00ac004.0.r.200316
AmcrestIp8m-2454ew Firmwarebefore v2.622.00ac000.0.r.200320v2.622.00ac000.0.r.200320
AmcrestIp8m-2493eb Firmwarebefore v2.622.00ac000.0.r.200320v2.622.00ac000.0.r.200320
AmcrestIp8m-2496eb Firmwarebefore v2.622.00ac000.0.r.200320v2.622.00ac000.0.r.200320
AmcrestIp8m-2597e Firmwarebefore v2.800.00ac000.0.r.200330v2.800.00ac000.0.r.200330
AmcrestIp8m-mb2546ew Firmwarebefore v2.622.00ac000.0.r.200320v2.622.00ac000.0.r.200320
AmcrestIp8m-mt2544ew Firmwarebefore v2.622.00ac000.0.r.200320v2.622.00ac000.0.r.200320
AmcrestIp8m-t2499ew Firmwarebefore v2.622.00ac000.0.r.200320v2.622.00ac000.0.r.200320
AmcrestIpm-hx1 Firmwarebefore v2.420.ac00.18.r.20200217v2.420.ac00.18.r.20200217

Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.

How the severity score breaks down

Attack vector
NetworkCan be exploited remotely over a network, including the internet.
Attack complexity
LowNo special conditions are needed; the attack works reliably.
Privileges required
LowA basic user account is enough.
User interaction
NoneNo action by a victim is required.
Scope
UnchangedImpact stays within the vulnerable component.
Confidentiality
HighAll data handled by the component can be read.
Integrity
HighData or code can be modified at will.
Availability
HighThe component can be taken down completely.

Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H. Scored by NVD.

Scoring systemScoreSeverityScored by
CVSS 3.18.8HighNVD
CVSS 3.18.8HighCISA (ADP)
CVSS 2.08.0HighNVD

Official description

Amcrest cameras and NVR are vulnerable to a stack-based buffer overflow over port 37777. An authenticated remote attacker can abuse this issue to crash the device and possibly execute arbitrary code.

Source: the CVE record as published by its numbering authority, via NVD and CVE.org.

The underlying weakness: Out-of-bounds Write

The product writes data past the end, or before the beginning, of the intended buffer.

How developers prevent this class of flaw

  • Use a language that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid. For example, many languages that perform their own memory management, such as Java and Perl, are not subject to buffer overflows. Other languages, such as Ada and C#, typically provide overflow protection, but the protection can be disabled by the programmer. Be wary that a language's interface to native code may still be subject to overflows, even if the language itself is theoretically safe.
  • Use a vetted library or framework that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid. Examples include the Safe C String Library (SafeStr) by Messier and Viega, and the Strsafe.h library from Microsoft. These libraries provide safer versions of overflow-prone string-handling functions.
  • Use automatic buffer overflow detection mechanisms that are offered by certain compilers or compiler extensions. Examples include: the Microsoft Visual Studio /GS flag, Fedora/Red Hat FORTIFY_SOURCE GCC flag, StackGuard, and ProPolice, which provide various mechanisms including canary-based detection and range/index checking. D3-SFCV (Stack Frame Canary Validation) from D3FEND discusses canary-based detection in detail.

More Out-of-bounds Write vulnerabilities (CWE-787)

Timeline

  1. CVE record published.
  2. Added to CISA's Known Exploited Vulnerabilities catalogue.
  3. Deadline for US federal agencies to remediate, set by CISA.
  4. CISA published its SSVC assessment (exploitation: active, automatable: no, technical impact: total).
  5. Record last changed materially (score, affected products, status or references).

References

Third-party and government advisories

Technical write-ups (may include proof of concept)

Recent Out-of-bounds Write vulnerabilities

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