Attack vector
LOCAL Attack complexity
HIGH Privileges required
LOW Confidentiality impact
HIGH Integrity impact
HIGH Availability impact
HIGH Published: 2020-03-23
Updated: 2021-07-21
Summary
An exploitable stack buffer overflow vulnerability vulnerability exists in the iocheckd service "I/O-Check" functionality of WAGO PFC 200. An attacker can send a specially crafted packet to trigger the parsing of this cache file.At 0x1eb9c the extracted interface element name from the xml file is used as an argument to /etc/config-tools/config_interfaces interface=<contents of interface element> using sprintf(). The destination buffer sp+0x40 is overflowed with the call to sprintf() for any interface values that are greater than 512-len("/etc/config-tools/config_interfaces interface=") in length. Later, at 0x1ea08 strcpy() is used to copy the contents of the stack buffer that was overflowed sp+0x40 into sp+0x440. The buffer sp+0x440 is immediately adjacent to sp+0x40 on the stack. Therefore, there is no NULL termination on the buffer sp+0x40 since it overflowed into sp+0x440. The strcpy() will result in invalid memory access. An interface value of length 0x3c4 will cause the service to crash.
Vulnerable Configurations
| Part | Description | Count |
| OS | Wago | 1 |
| Hardware | Wago | 1 |
Common Weakness Enumeration (CWE)
Common Attack Pattern Enumeration and Classification (CAPEC)
- Buffer Overflow via Environment Variables
This attack pattern involves causing a buffer overflow through manipulation of environment variables. Once the attacker finds that they can modify an environment variable, they may try to overflow associated buffers. This attack leverages implicit trust often placed in environment variables.
- Overflow Buffers
Buffer Overflow attacks target improper or missing bounds checking on buffer operations, typically triggered by input injected by an attacker. As a consequence, an attacker is able to write past the boundaries of allocated buffer regions in memory, causing a program crash or potentially redirection of execution as per the attackers' choice.
- Client-side Injection-induced Buffer Overflow
This type of attack exploits a buffer overflow vulnerability in targeted client software through injection of malicious content from a custom-built hostile service.
- Filter Failure through Buffer Overflow
In this attack, the idea is to cause an active filter to fail by causing an oversized transaction. An attacker may try to feed overly long input strings to the program in an attempt to overwhelm the filter (by causing a buffer overflow) and hoping that the filter does not fail securely (i.e. the user input is let into the system unfiltered).
- MIME Conversion
An attacker exploits a weakness in the MIME conversion routine to cause a buffer overflow and gain control over the mail server machine. The MIME system is designed to allow various different information formats to be interpreted and sent via e-mail. Attack points exist when data are converted to MIME compatible format and back.