CyberSecBulletin
CVE-2024-7331NVD status: Analyzed

A3300R: Buffer Copy without Checking Size of Input

Published Updated By the CyberSecBulletin desk

CVE-2024-7331 is a high-severity buffer copy without checking size of input vulnerability in A3300R from TOTOLINK, 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. Affected A3300R versions: 17.0.0cu.557_B20221024. The record does not name a fixed version, so check the vendor advisory. There is no confirmed exploitation so far. EPSS estimates a 1.2% chance of exploitation within 30 days, higher than 69% of scored CVEs.

Next patch cycle

High severity with no evidence of exploitation so far.

What to do

  1. Check which version of A3300R you run against the affected versions below, and install the vendor's latest release.

Affected products and versions

VendorProductAffected versionsFixed in
TOTOLINKA3300R17.0.0cu.557_B20221024Not stated
TOTOLINKa3300r_firmware17.0.0cu.557_b20221024Not stated

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 4.08.7HighCNA (vuldb.com)
CVSS 3.18.8HighCNA (vuldb.com)
CVSS 3.18.8HighNVD
CVSS 2.09.0HighCNA (vuldb.com)

Official description

A vulnerability was found in TOTOLINK A3300R 17.0.0cu.557_B20221024 and classified as critical. Affected by this issue is the function UploadCustomModule of the file /cgi-bin/cstecgi.cgi. The manipulation of the argument File leads to buffer overflow. The attack may be launched remotely. The exploit has been disclosed to the public and may be used. VDB-273254 is the identifier assigned to this vulnerability. NOTE: The vendor was contacted early about this disclosure but did not respond in any way.

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

The underlying weakness: Buffer Copy without Checking Size of Input

The product copies an input buffer to an output buffer without verifying that the size of the input buffer is less than the size of the output 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 Buffer Copy without Checking Size of Input vulnerabilities (CWE-120)

Timeline

  1. CVE record published.
  2. CISA published its SSVC assessment (exploitation: poc, automatable: yes, technical impact: partial).
  3. Record last changed materially (score, affected products, status or references).

References

Third-party and government advisories

Technical write-ups (may include proof of concept)

Other references

Other vulnerabilities in A3300R

All A3300R vulnerabilities

Recent Buffer Copy without Checking Size of Input vulnerabilities

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