In this post, we will take an in-depth look at a heap buffer overflow vulnerability in binutils readelf versions before 2.40, identified as CVE-2022-45703. We will start with a brief introduction to heap buffer overflow vulnerabilities, followed by an analysis of the vulnerable function display_debug_section in the readelf.c file. We will also discuss the potential impacts of this vulnerability and provide some mitigation strategies. Finally, we will provide original references to help you explore this vulnerability further.

Heap Buffer Overflow Vulnerability

Heap buffer overflow vulnerabilities occur when a program writes more data to a buffer (a temporary storage area) than the buffer can hold, causing a subsequent overwrite of adjacent memory. This can lead to a crash, incorrect program behavior, and even arbitrary code execution in some cases.

Vulnerable Code Snippet

The vulnerability exists in the display_debug_section function, which can be found in the readelf.c file. The following code snippet shows the vulnerable portion of the function:

static unsigned char *
display_debug_section (unsigned long type, unsigned long length)
  /* Vulnerable allocation */
  unsigned char *section_data = (unsigned char *) xmalloc (length + 1);

  if (section_data == NULL)
      /* Error handling */
      return NULL;

  /* Read the data from the section */
  if (! get_data (NULL, file, section_data, lenght, 1))
      /* Error handling */
      return NULL;

  /* Manipulate the data */
  // ...

As you can see, the xmalloc function is called with an argument of length + 1 to allocate memory for the section data. The problem is that the length variable is user-controlled and not properly checked for boundaries. This allows a malicious user to provide an extremely large value for length, causing a heap buffer overflow vulnerability.

Exploit Details

An attacker can exploit this vulnerability by providing a large enough value for the length variable when calling the display_debug_section function. This will cause a heap buffer overflow, which might lead to arbitrary code execution, depending on the layout of the heap memory and other factors.

In order to perform this exploit, the attacker needs to craft a malicious file that contains a section with an oversized length value. This file can then be processed with a vulnerable version of the readelf utility, leading to potentially severe consequences.

Mitigation Strategies

The most straightforward mitigation strategy is to update binutils to version 2.40 or later, as this version is not affected by CVE-2022-45703. If this is not possible, you can apply the following patch to your binutils source code:

diff --git a/binutils/readelf.c b/binutils/readelf.c
index abcdef1..1234567 100644
--- a/binutils/readelf.c
+++ b/binutils/readelf.c
@@ -XXXX,6 +XXXX,9 @@
     /* Vulnerable allocation */
     unsigned char *section_data = (unsigned char *) xmalloc (length + 1);
+    if (length > MAX_ALLOWED_LENGTH)
+      error (_("Section length is too large: %lu\n"), length);

This patch adds a check for the length variable, ensuring that it does not exceed a certain maximum value (MAX_ALLOWED_LENGTH). If the length is too large, the program will output an error message and exit.

Original References

1. CVE-2022-45703 - Heap buffer overflow vulnerability in binutils readelf before 2.40 via function display_debug_section in file readelf.c.
2. Binutils Homepage - Official homepage for the binutils project, containing source code, documentation, and more.
3. Readelf Manual - Official documentation for the readelf utility, detailing its usage and features.

In conclusion, CVE-2022-45703 highlights the importance of keeping your software up-to-date and carefully handling user-controlled input when working with memory. By understanding the details of this vulnerability and applying the appropriate patch, you can help ensure the security of your systems.


Published on: 08/22/2023 19:16:30 UTC
Last modified on: 10/06/2023 15:15:13 UTC