fkie_cve-2025-68183
Vulnerability from fkie_nvd
Published
2025-12-16 14:15
Modified
2025-12-18 15:08
Severity ?
Summary
In the Linux kernel, the following vulnerability has been resolved:
ima: don't clear IMA_DIGSIG flag when setting or removing non-IMA xattr
Currently when both IMA and EVM are in fix mode, the IMA signature will
be reset to IMA hash if a program first stores IMA signature in
security.ima and then writes/removes some other security xattr for the
file.
For example, on Fedora, after booting the kernel with "ima_appraise=fix
evm=fix ima_policy=appraise_tcb" and installing rpm-plugin-ima,
installing/reinstalling a package will not make good reference IMA
signature generated. Instead IMA hash is generated,
# getfattr -m - -d -e hex /usr/bin/bash
# file: usr/bin/bash
security.ima=0x0404...
This happens because when setting security.selinux, the IMA_DIGSIG flag
that had been set early was cleared. As a result, IMA hash is generated
when the file is closed.
Similarly, IMA signature can be cleared on file close after removing
security xattr like security.evm or setting/removing ACL.
Prevent replacing the IMA file signature with a file hash, by preventing
the IMA_DIGSIG flag from being reset.
Here's a minimal C reproducer which sets security.selinux as the last
step which can also replaced by removing security.evm or setting ACL,
#include <stdio.h>
#include <sys/xattr.h>
#include <fcntl.h>
#include <unistd.h>
#include <string.h>
#include <stdlib.h>
int main() {
const char* file_path = "/usr/sbin/test_binary";
const char* hex_string = "030204d33204490066306402304";
int length = strlen(hex_string);
char* ima_attr_value;
int fd;
fd = open(file_path, O_WRONLY|O_CREAT|O_EXCL, 0644);
if (fd == -1) {
perror("Error opening file");
return 1;
}
ima_attr_value = (char*)malloc(length / 2 );
for (int i = 0, j = 0; i < length; i += 2, j++) {
sscanf(hex_string + i, "%2hhx", &ima_attr_value[j]);
}
if (fsetxattr(fd, "security.ima", ima_attr_value, length/2, 0) == -1) {
perror("Error setting extended attribute");
close(fd);
return 1;
}
const char* selinux_value= "system_u:object_r:bin_t:s0";
if (fsetxattr(fd, "security.selinux", selinux_value, strlen(selinux_value), 0) == -1) {
perror("Error setting extended attribute");
close(fd);
return 1;
}
close(fd);
return 0;
}
References
Impacted products
| Vendor | Product | Version |
|---|
{
"cveTags": [],
"descriptions": [
{
"lang": "en",
"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nima: don\u0027t clear IMA_DIGSIG flag when setting or removing non-IMA xattr\n\nCurrently when both IMA and EVM are in fix mode, the IMA signature will\nbe reset to IMA hash if a program first stores IMA signature in\nsecurity.ima and then writes/removes some other security xattr for the\nfile.\n\nFor example, on Fedora, after booting the kernel with \"ima_appraise=fix\nevm=fix ima_policy=appraise_tcb\" and installing rpm-plugin-ima,\ninstalling/reinstalling a package will not make good reference IMA\nsignature generated. Instead IMA hash is generated,\n\n # getfattr -m - -d -e hex /usr/bin/bash\n # file: usr/bin/bash\n security.ima=0x0404...\n\nThis happens because when setting security.selinux, the IMA_DIGSIG flag\nthat had been set early was cleared. As a result, IMA hash is generated\nwhen the file is closed.\n\nSimilarly, IMA signature can be cleared on file close after removing\nsecurity xattr like security.evm or setting/removing ACL.\n\nPrevent replacing the IMA file signature with a file hash, by preventing\nthe IMA_DIGSIG flag from being reset.\n\nHere\u0027s a minimal C reproducer which sets security.selinux as the last\nstep which can also replaced by removing security.evm or setting ACL,\n\n #include \u003cstdio.h\u003e\n #include \u003csys/xattr.h\u003e\n #include \u003cfcntl.h\u003e\n #include \u003cunistd.h\u003e\n #include \u003cstring.h\u003e\n #include \u003cstdlib.h\u003e\n\n int main() {\n const char* file_path = \"/usr/sbin/test_binary\";\n const char* hex_string = \"030204d33204490066306402304\";\n int length = strlen(hex_string);\n char* ima_attr_value;\n int fd;\n\n fd = open(file_path, O_WRONLY|O_CREAT|O_EXCL, 0644);\n if (fd == -1) {\n perror(\"Error opening file\");\n return 1;\n }\n\n ima_attr_value = (char*)malloc(length / 2 );\n for (int i = 0, j = 0; i \u003c length; i += 2, j++) {\n sscanf(hex_string + i, \"%2hhx\", \u0026ima_attr_value[j]);\n }\n\n if (fsetxattr(fd, \"security.ima\", ima_attr_value, length/2, 0) == -1) {\n perror(\"Error setting extended attribute\");\n close(fd);\n return 1;\n }\n\n const char* selinux_value= \"system_u:object_r:bin_t:s0\";\n if (fsetxattr(fd, \"security.selinux\", selinux_value, strlen(selinux_value), 0) == -1) {\n perror(\"Error setting extended attribute\");\n close(fd);\n return 1;\n }\n\n close(fd);\n\n return 0;\n }"
}
],
"id": "CVE-2025-68183",
"lastModified": "2025-12-18T15:08:25.907",
"metrics": {},
"published": "2025-12-16T14:15:50.880",
"references": [
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/02aa671c08a4834bef5166743a7b88686fbfa023"
},
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/88b4cbcf6b041ae0f2fc8a34554a5b6a83a2b7cd"
},
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/d2993a7e98eb70c737c6f5365a190e79c72b8407"
},
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/edd824eb45e4f7e05ad3ab090dab6dbdb79cd292"
}
],
"sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"vulnStatus": "Awaiting Analysis"
}
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Sightings
| Author | Source | Type | Date |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or seen somewhere by the user.
- Confirmed: The vulnerability is confirmed from an analyst perspective.
- Published Proof of Concept: A public proof of concept is available for this vulnerability.
- Exploited: This vulnerability was exploited and seen by the user reporting the sighting.
- Patched: This vulnerability was successfully patched by the user reporting the sighting.
- Not exploited: This vulnerability was not exploited or seen by the user reporting the sighting.
- Not confirmed: The user expresses doubt about the veracity of the vulnerability.
- Not patched: This vulnerability was not successfully patched by the user reporting the sighting.
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