cbcvebase.
CVE-2017-15715
published 2018-03-26

CVE-2017-15715: In Apache httpd 2.4.0 to 2.4.29, the expression specified in could match '$' to a newline character in a malicious filename, rather than matching only the end…

PriorityP182high8.1CVSS 3.0
AVNACHPRNUINSUCHIHAH
ITWEXPLOITVulnCheck KEVInitial access
Exploited in the wild
EPSS
86.01%
99.7th percentile
In Apache httpd 2.4.0 to 2.4.29, the expression specified in could match '$' to a newline character in a malicious filename, rather than matching only the end of the filename. This could be exploited in environments where uploads of some files are are externally blocked, but only by matching the trailing portion of the filename.

Affected

14 ranges
VendorProductVersion rangeFixed in
apachehttp_server2.4.0 – 2.4.29
apache_software_foundationapache_http_server
canonicalubuntu_linux
canonicalubuntu_linux
canonicalubuntu_linux
canonicalubuntu_linux
debianapache2< apache2 2.4.33-1 (bookworm)apache2 2.4.33-1 (bookworm)
debiandebian_linux
debiandebian_linux
redhatenterprise_linux
redhatenterprise_linux
redhatenterprise_linux
redhatenterprise_linux
redhatenterprise_linux

Detection & IOCsextracted from sources · hover to see the quote

commandPOST / HTTP/1.1 with multipart/form-data filename containing \x0A (newline) suffix
urlGET /{{randstr}}.php\x0A
  • Look for multipart file upload POST requests where the submitted filename contains a trailing newline character (\x0A / 0x0a) appended after the extension (e.g., 'shell.php\x0A'), which is the bypass payload for FilesMatch regex controls.
  • Detect subsequent GET requests to uploaded files whose path contains a trailing newline (\x0A) — this indicates exploitation of the bypass to execute the uploaded file.
  • The vulnerability is only exploitable when the FilesMatch directive is explicitly enabled in httpd configuration; audit configs for FilesMatch usage combined with file-upload endpoints.
  • The exploit abuses '$' in a FilesMatch regex matching a newline rather than end-of-string; monitor for filenames with embedded newline characters in HTTP Content-Disposition headers.
  • The upstream fix introduced 'RegexDefaultOptions' directive to force '$' to match end-of-input only; absence of this directive or of httpd >= 2.4.33 on upload-capable servers is a risk indicator.
  • ·Exploitation requires FilesMatch to be explicitly configured; default Apache httpd installs are not affected.
  • ·The attack is only viable in environments where file uploads are externally blocked by matching only the trailing portion of the filename via regex.
  • ·Red Hat Satellite 6 enables FilesMatch but is not considered an attack vector because users cannot modify filenames in the concerned directories.

CVSS provenance

nvdv3.08.1HIGHCVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
nvdv2.06.8MEDIUMAV:N/AC:M/Au:N/C:P/I:P/A:P
osv8.1HIGH
vulncheck8.1HIGH
vendor_debian8.1HIGH
vendor_redhat8.1HIGH
vendor_ubuntu7.5HIGH
CVEs like this are exactly what “Exploited This Week” covers.

Every Monday: what got weaponized or added to CISA KEV in the last seven days — each CVE cross-linked to its PoC, Nuclei template, and detection rule. Free, one email a week, unsubscribe in one click.