Sigma rule: Potential CVE-2021-27905 Exploitation Attempt

Rule

Title

Potential CVE-2021-27905 Exploitation Attempt

Status

test

Level

medium

Author

@gott_cyber

Date

2022-12-11

Modified

2023-03-24

File

rules-emerging-threats/2021/Exploits/CVE-2021-27905/web_cve_2021_27905_apache_solr_exploit.yml

Commit

ccbb0369507f796db0b0ae6854c8a2be471b9d84

Detects exploitation attempt of the CVE-2021-27905 which affects all Apache Solr versions prior to and including 8.8.1.

Log source

category

webserver

Detection

selection_request1:
    cs-uri-query|contains|all:
        - '/solr/'
        - '/debug/dump?'
        - 'param=ContentStream'
    sc-status: 200
selection_request2:
    cs-method: 'GET'
    cs-uri-query|contains|all:
        - '/solr/'
        - 'command=fetchindex'
        - 'masterUrl='
    sc-status: 200
condition: 1 of selection_*

False positives (as the rule lists them)

• Vulnerability Scanners

Tags

• attack.initial-access
• attack.t1190
• cve.2021-27905
• detection.emerging-threats

CVEs this rule names

• CVE-2021-27905

MITRE ATT&CK ids this rule names

• T1190

References

• https://twitter.com/Al1ex4/status/1382981479727128580
• https://twitter.com/sec715/status/1373472323538362371
• https://nsfocusglobal.com/apache-solr-arbitrary-file-read-and-ssrf-vulnerability-threat-alert/
• https://mp.weixin.qq.com/s?__biz=Mzg3NDU2MTg0Ng==&mid=2247484117&idx=1&sn=2fdab8cbe4b873f8dd8abb35d935d186
• https://github.com/murataydemir/CVE-2021-27905

Read on 2026-11-03T00:58:21.399Z under licence sigma-drl-1.1@d5f4c36a from https://github.com/SigmaHQ/sigma/blob/ccbb0369507f796db0b0ae6854c8a2be471b9d84/rules-emerging-threats/2021/Exploits/CVE-2021-27905/web_cve_2021_27905_apache_solr_exploit.yml