CAPEC-67

How the attack unfolds

1. Explore

   The attacker looks for a way in.

   1. [Identify target application] The adversary identifies a target application or program to perform the buffer overflow on. In this attack, adversaries look for applications that use syslog() incorrectly.

2. Experiment

   They probe what they found.

   2. [Find injection vector] The adversary identifies an injection vector to deliver the excessive content to the targeted application's buffer. For each user-controllable input that the adversary suspects is vulnerable to format string injection, attempt to inject formatting characters such as %n, %s, etc.. The goal is to manipulate the string creation using these formatting characters.

      1 technique

      • Inject probe payload which contains formatting characters (%s, %d, %n, etc.) through input parameters.

   3. [Craft overflow content] The adversary crafts the content to be injected. If the intent is to simply cause the software to crash, the content need only consist of an excessive quantity of random data. If the intent is to leverage the overflow for execution of arbitrary code, the adversary will craft a set of content that not only overflows the targeted buffer but does so in such a way that the overwritten return address is replaced with one of the adversaries' choosing which points to code injected by the adversary.

      2 techniques

      • The formatting characters %s and %d are useful for observing memory and trying to print memory addresses. If an adversary has access to the log being written to they can observer this output and use it to help craft their attack.
      • The formatting character %n is useful for adding extra data onto the buffer.

3. Exploit

   They carry out the attack.

   4. [Overflow the buffer] Using the injection vector, the adversary supplies the program with the crafted format string injection, causing a buffer.

Prerequisites

• The Syslog function is used without specifying a format string argument, allowing user input to be placed direct into the function call as a format string.

Consequences

Mitigations

• The code should be reviewed for misuse of the Syslog function call. Manual or automated code review can be used. The reviewer needs to ensure that all format string functions are passed a static string which cannot be controlled by the user and that the proper number of arguments are always sent to that function as well. If at all possible, do not use the %n operator in format strings. The following code shows a correct usage of Syslog():

  syslog(LOG_ERR, "%s", cmdBuf);

  The following code shows a vulnerable usage of Syslog():

  syslog(LOG_ERR, cmdBuf);
  // the buffer cmdBuff is taking user supplied data.

Weaknesses it exploits

• CWE-20 Improper Input Validation
• CWE-74 Improper Neutralization of Special Elements in Output Used by a Downstream Component
• CWE-120 Buffer Copy without Checking Size of Input
• CWE-134 Use of Externally-Controlled Format String
• CWE-680 Integer Overflow to Buffer Overflow
• CWE-697 Incorrect Comparison

Recent CVEs with these weaknesses

1. 9.6CVE-2026-1081862026-11-10

   Improper Input Validation in Zoom Workplace for Windows may allow an unauthenticated user to conduct an escalation of privilege via network access.

2. 4.9CVE-2026-1054272026-11-10

   Improper input validation in Ivanti EPMM before version 12.10.0.1, 12.9.0.3, and 12.8.0.5 allows a remote authenticated attacker with admin privileges to permanently disable all Apache HTTPS services resulting in denial of service.

3. 6.7CVE-2026-1054262026-11-10

   Improper input validation in Ivanti EPMM before version 12.10.0.1, 12.9.0.3, and 12.8.0.5 allows a remote authenticated attacker with admin privileges to set arbitrary Linux kernel parameters as root.

4. 4.3CVE-2026-1231782026-11-10

   An insufficient input validation vulnerability in the listed NETGEAR Orbi Models router allows an authenticated administrator connected to the local network to execute unauthorized commands and modify the router’s software and functionalit…

5. 8.8CVE-2026-1249472026-11-10

   Incorrect boundary conditions in the Graphics component. This vulnerability was fixed in Firefox 160.

6. 8.8CVE-2026-1249262026-11-10

   Incorrect boundary conditions in the WebRTC component. This vulnerability was fixed in Firefox 160 and Firefox ESR 153.7.

7. 8.8CVE-2026-1249242026-11-10

   Incorrect boundary conditions in the Graphics: WebRender component. This vulnerability was fixed in Firefox 160 and Firefox ESR 153.7.

8. 8.8CVE-2026-1249182026-11-10

   Privilege escalation due to incorrect boundary conditions in the Graphics: WebRender component. This vulnerability was fixed in Firefox 160 and Firefox ESR 153.7.

The newest records naming one of them. Each weakness's page lists them all.

Related attack patterns

Part of

• CAPEC-100 Overflow Buffers
• CAPEC-135 Format String Injection

Examples

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