Vigil@nce: Linux kernel, privilege elevation via eCryptfs
August 2009 by Vigil@nce
A local attacker, allowed to mount a eCryptfs filesystem, can
generate an overflow in order to elevate his privileges.
Severity: 2/4
Consequences: administrator access/rights
Provenance: user shell
Means of attack: no proof of concept, no attack
Ability of attacker: expert (4/4)
Confidence: confirmed by the editor (5/5)
Diffusion of the vulnerable configuration: high (3/3)
Number of vulnerabilities in this bulletin: 2
Creation date: 29/07/2009
IMPACTED PRODUCTS
– Debian Linux
– Fedora
– Linux kernel
– Red Hat Enterprise Linux
DESCRIPTION OF THE VULNERABILITY
The Linux kernel supports the eCryptfs file system since version
2.6.19. This implementation has two vulnerabilities.
When the encryption key is superior to ECRYPTFS_MAX_ENCRYPTED_KEY_BYTES,
an overflow occurs in the parse_tag_3_packet() function.
[grav:2/4; BID-35850, CVE-2009-2407, RISE-2009003]
When the size of data (tag11_contents_size) is superior to
max_contents_bytes, an overflow occurs in the parse_tag_1_packet()
function. [grav:2/4; BID-35851, CVE-2009-2406, RISE-2009002]
A local attacker, allowed to mount a malicious eCryptfs
filesystem, can therefore generate an overflow in order to elevate
his privileges.
CHARACTERISTICS
Identifiers: BID-35850, BID-35851, CVE-2009-2406, CVE-2009-2407,
DSA 1844-1, DSA 1845-1, FEDORA-2009-8144, FEDORA-2009-8264,
RHSA-2009:1193-01, RISE-2009002, RISE-2009003, VIGILANCE-VUL-8899
http://vigilance.fr/vulnerability/Linux-kernel-privilege-elevation-via-eCryptfs-8899